MECHATRONICS TROUBLESHOOTING LEARNING · PDF file · 2017-01-03covers the types of failures that occur and how to diagnose those problems. ... SKILL 2 Troubleshoot a mechatronics

LEARNINGACTIVITYPACKET

MECHATRONICSTROUBLESHOOTING

INTRODUCTION TOMECHATRONICSTROUBLESHOOTING(SIEMENS S7-300/STEP 7)

B25015-BA01UEN

B25015-BA01UEN INTRODUCTION TO MECHATRONICS TROUBLESHOOTINGCopyright © 2013 Amatrol, Inc.

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LEARNING ACTIVITY PACKET 1

INTRODUCTION TO MECHATRONICS TROUBLESHOOTING

INTRODUCTIONThis LAP serves as an introduction to troubleshooting mechatronics failures. It

covers the types of failures that occur and how to diagnose those problems.

Downtime, or the time the manufacturing line is not producing, can cost thousands of dollars per minute. To minimize downtime, the technician must thoroughly understand the machines and components in his or her area and be able to quickly act as failures arise.

This LAP covers the types of failures in PLC-controlled mechatronics systems including diagnostic indicators, power supplies, and I/O. It will also discuss troubleshooting faults in power supplies, input devices and input modules, and output devices and output modules.

ITEMS NEEDEDAmatrol Supplied 87-FTSS7-BAX Mechatronics Troubleshooting Learning System for Siemens S7 - one per station One or more of the following mechatronics Stations: 87-MS1 Pick and Place Feeding Station 87-MS2 Gauging Station 87-MS3 Indexing Station 87-MS4 Sorting and Queuing Station 87-MS5 Servo Robotic Assembly Station 87-MS6 Torquing Station 87-MS7 Parts Storage Station One of the following PLC controls per station 870-PS7313-BAU, 870-PS7314-BAU, or 870-PS7315-BAU Mechatronics Learning System for Siemens S7-300 72024 Siemens S7-300 Programming Cable - one per station

Amatrol or School Supplied 82-900 Siemens Step 7 Programming Software - one per station

School Supplied Computer with Windows XP or Windows 7 Operating System with two or more USB ports Multimeter

FIRST EDITION, LAP 1, REV. BAmatrol, AMNET, CIMSOFT, MCL, MINI-CIM, IST, ITC, VEST, and Technovate are trademarks or registered trademarks of Amatrol, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies.Copyright © 2013, 2012 by AMATROL, INC.All rights Reserved. No part of this publication may be reproduced, translated, or transmitted in any form or by any means, electronic, optical, mechanical, or magnetic, including but not limited to photographing, photocopying, recording or any information storage and retrieval system, without written permission of the copyright owner.Amatrol,Inc., 2400 Centennial Blvd., Jeffersonville, IN 47130 USA, Ph 812-288-8285, FAX 812-283-1584 www.amatrol.com


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TABLE OF CONTENTS

SEGMENT 1 MECHATRONICS TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4OBJECTIVE 1 Describe two levels of troubleshooting and give an application of eachOBJECTIVE 2 Describe six types of PLC faultsOBJECTIVE 3 Describe the functions of S7-300 status and diagnostic indicators

SKILL 1 Use S7-300 status indicators to determine the status of PLC operation

SEGMENT 2 MECHATRONICS POWER SUPPLY TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . 26OBJECTIVE 4 Describe the operation of a mechatronics power supply circuitOBJECTIVE 5 Describe how to troubleshoot mechatronics power supply problemsOBJECTIVE 6 Describe how to troubleshoot a mechatronics power supply

SKILL 2 Troubleshoot a mechatronics power supply

SEGMENT 3 MECHATRONICS INPUT TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57OBJECTIVE 7 Describe how to test mechatronics discrete input devices

SKILL 3 Test mechatronics discrete input devicesOBJECTIVE 8 Describe how to test a discrete input module

SKILL 4 Test a discrete input module

SEGMENT 4 MECHATRONICS OUTPUT TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80OBJECTIVE 9 Describe the PLC Force function and give an applicationOBJECTIVE 10 Describe how to force a PLC input or output using a variable table

SKILL 5 Force inputs and outputs using a variable tableOBJECTIVE 11 Describe how to test a PLC discrete output device

SKILL 6 Test a discrete output deviceOBJECTIVE 12 Describe how to test a discrete output module

SKILL 7 Test a discrete output module


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SEGMENT 1MECHATRONICS TROUBLESHOOTING

OBJECTIVE 1 DESCRIBE TWO LEVELS OF TROUBLESHOOTINGAND GIVE AN APPLICATION OF EACH

Troubleshooting is the process of fi nding the cause or fault of a machine malfunction. Faults may cause a machine to do many things. For example, the fault could cause the machine to stop, skip a step, or perform a step incorrectly.

The malfunction is called the symptom. All troubleshooting begins with iden-tifying the symptom or symptoms. What follows should be a methodical trouble-shooting process to fi nd the fault as quickly as possible and fi x it.

Figure 1. Troubleshooting a PLC


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Mechatronics system troubleshooting can be performed at one of two levels: • Systems Level Troubleshooting• Component Level Troubleshooting

Systems Level Troubleshooting

Systems level troubleshooting is a process where the troubleshooter identi-fi es, through observation and measurement, the failed component of a system (i.e. power supply, processor, input or output module, or fi eld device). For example, if a Mechatronics system cannot turn on an output, a systems level troubleshooting process would involve fi nding the failed component. One such component could be an output module. In this process, the whole output module is replaced. The faulty component can be repaired later locally or shipped to a service depot for repair. Because machine downtime is so expensive for a manufacturer, most main-tenance personnel in manufacturing plants usually only perform systems level troubleshooting.

Component Level Troubleshooting

Component level troubleshooting is a process where the troubleshooter repairs the faulty component identifi ed through systems level troubleshooting. This means fi nding the parts (i.e. IC, resistor, diode) within the component that must be replaced to repair it. This often requires manufacturer’s documentation that is not available locally, and time that is not available while the component is still installed in the machine. For these reasons, component level troubleshooting is generally performed off-line, away from the machine.

For example, the failed output module identifi ed above would be tested to fi nd and repair the faulty component(s) on the circuit boards inside the module.


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OBJECTIVE 2 DESCRIBE SIX TYPES OF PLC FAULTS

Mechatronics troubleshooting involves the mechanical, pneumatic/hydraulic, electrical, electronic, and programmable control systems of a manufacturing process. Because the PLC interacts with all of the other systems, a common prac-tice is to troubleshoot failures using the PLC tools and utilities. In some cases, the failure may be the PLC itself. Although the PLC is the most reliable component in the system, it does fail from time to time and the troubleshooter must be able to identify the problem.

There are six main categories of faults that can cause a programmable controller system to fail:

• Processor Hardware• Processor Projects• Power Supply and Master Control Relay Circuit• Input/ Output Modules• Input/ Output Field Devices• PLC Networks

Figure 2. Types of PLC Faults

PS3072A

DC24V

120V

VOLTAGESELECTOR

SFBATFDCSVFRCERUNSTOP

SIEMENS

RUN-P

RUN

STOP

MRES

M

L+

M

CPU 3XX

SIMATICS7-300

PROCESSOR PROJECT

PROCESSORHARDWARE

INPUT/OUTPUT MODULES

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*SOLENOID*MOTOR STARTERS*LIMIT SWITCHES*ELECTRONIC SENSORS

AUTOMATIC INPUT/OUTPUT DEVICES

*INDICATORS*PUSHBUTTONS*SELECTORSWITCHES

MANUAL INPUT/OUTPUT DEVICES

POWER SUPPLYMODULE

307-1EA00-00A0

END

ONOFF


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Processor Hardware

The processor is an industrially hardened computer. It is susceptible to hard-ware failures just like any other computer. If the processor module’s internal circuitry fails and produces a fault in the processor, program execution is halted. Failed processors must be repaired or replaced.

Processor Projects

Processor projects, or programs, may also introduce fault conditions, either by design or by accident. Program faults may be major (causing the processor to stop program execution) or minor (possibly slowing processor operation) in nature.

Power Supply and Master Control Relay Circuit

The power supply consists of the master control relay circuit (which supplies AC to the DC power supply) and the DC power supply (which supplies DC power to run the processor module as well as any other module installed on the rack). Power supplies may be mounted directly to the rack, external to the rack, or a combination of the two.

Failures that occur in the master control relay circuit are the same as those typically found in any relay circuit (e.g. bad contacts, pushbuttons, or relay contac-tors), and can be repaired by replacing the defective component. The power supply may fail entirely due to an internal short or open condition (in which case, no power is produced), or may produce insuffi cient power for the number and/or type of modules installed on the rack.

Input/Output Modules

The input and output modules contain electronic circuitry that enable them to interface with and control the I/O devices. As with other electronic components, the electronic circuitry of the I/O modules may become damaged and/or fail. This type of failure may fault a single point, several points, or the entire module.

In addition to the electronic circuitry, output modules usually have some form of fuse protection that opens the connections between the module’s output and the output device in the case of a short circuit or over current condition. Depending upon the output module, fuses may be replaceable, electronic or mechanical. Open or “blown” fuses may appear as a defective output point, module, or output device. Blown fuses are fi eld repairable, failed cards should be replaced and then repaired by a factory authorized service center.


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Input/Output Field Devices

These devices include the switches, solenoids, indicators, and other fi eld devices that connect to I/O modules to control the process. They most often fail in either a closed or open condition. This creates the same effect as a bad point on the I/O module. Faulty I/O devices are replaced.

Another source of failure is the wiring that connects the fi eld devices to the I/O modules. This causes the same effect as a bad fi eld device. The wiring can either break, which causes an open, or it can short circuit.

Input and output fi eld devices have the highest failure rate of any components in the PLC-based control system. This is because these devices are in contact with or close proximity to fast-operating equipment in an often-harsh environment.

For example, consider a limit switch that closes when a clamp on a spot welding fi xture closes. The switch must not only endure the cycling of the clamp, but also the heat and electrical fi elds from the resultant welding operation.

PLC Networks

As networks and networking increase in PLC applications, so does the number of faults associated with them. Networks enable the controller to read and control I/O devices located all over the plant fl oor, provide status, control, and alarm data to production workers and electricians, and share production counts and data between controllers and management.

Networks can be a source of faults in the PLC system. PLC network faults may be the result of damaged or incorrectly wired network cabling, or an incorrectly confi gured device.


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OBJECTIVE 3 DESCRIBE THE FUNCTIONS OF S7-300 STATUSAND DIAGNOSTIC INDICATORS

One of the tools the PLC provides to help monitor and troubleshoot the system are status or diagnostic indicators. These indicators are built into the front panel of each module. Following a failure, they are checked fi rst by technicians to make sure the system is working correctly and to help fi nd a fault quickly.

Figure 3. Basic Status Indicators on the 315-2DP Processor

PLC status and diagnostic indicators can be organized according to the type of module on which they reside. The diagnostic indicators covered in this LAP are:

• Processor Module Indicators• Discrete Input Module Indicators• Discrete Output Module Indicators• Power Supply Indicators

SYSTEM FAULT

BUS FAULT

5VDC FAULT

FORCE

RUN

STOP

CPU315-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIMATICS7-300

SIEMENS


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Processor Module Indicators

The S7-315-2DP processor provides six basic indicators, as shown in fi gure 3. The function of each of these indicators is described in the table shown in fi gure 4.

INDICATOR STATE STATUS

SF Off No software or hardware error is present.

Red A hardware or software error is detected in the system.

BF Off No bus fault is detected.

Red A bus fault has been detected in the system.

DC5V Off The 5VDC power supplied by the CPU is faulty.

Green The 5VDC power supplied by the CPU to the other modules is OK.

FRCE Off No forces are enabled in the processor.

Yellow One or more input or output addresses have been forced to an On or Off state.

RUN Off The processor is either off, or in STOP mode.

Green The processor is in RUN mode.

STOP Off The processor is either off, in RUN mode, or in RUN-P mode.

Yellow The CPU is in STOP mode.

Flashing Yellow

The CPU is in either Startup or Reset mode.

Figure 4. Processor Indicators


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In addition to understanding the function of the processor’s status indicators, a good technician should also know the probable cause of and action required to clear the fault. The table shown in fi gure 5 lists the probable causes and actions required to clear faults associated with the processor’s status indicators.

INDICATOR STATE STATUS RECOMMENDED ACTION

SF Off No software or hardware error is present. No action required.

Red A hardware or software error is detected in the system.

1. Go online with the processor.2. Use the software to try to determine the cause of the fault.

BF Off No bus fault is detected. No action required.

Red A bus fault has been detected in the system. Troubleshoot the processor.Troubleshoot the Profi bus network.

DC5V Off 5VDC power for the CPU and S7-300 bus is faulty. Troubleshoot the power supply circuitry.

Green 5VDC power for the CPU and S7-300 bus is ok. No action required.

FRCE Off No forces are enabled in the processor. No action required.

Yellow One or more input or output addresses have been forced to an On or Off state and enabled.

1. Monitor the program online and identify the forced I/O.2. Disable the forces and test operation again.

RUN Off The processor is either off, or in STOP mode. Use the mode selector switch to place the processor into Run mode.

Green The processor is in RUN mode. No action required.

STOP Off The processor is either off, in RUN mode, or in RUN-P mode.

No action required.

Yellow The CPU is in STOP mode. Use the mode selector switch to place the processor into RUN mode.

Flashing Yellow

The CPU is in either Startup or Reset mode. Allow the startup or reset to complete.

Figure 5. Processor Indicators and Recommended Actions


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Discrete Input Module Indicators

The indicators on most S7-300 input modules, shown in fi gure 6, light green to indicate the input is receiving an input voltage. Some S7-300 modules have built-in diagnostic capabilities. These modules include an SF indicator that illuminates red when an error is sensed by the module.

Figure 6. Discrete Input Module Indicators

INPUTSTATUS

INDICATORS

INPUTSTATUS

INDICATORS

SM321DI 16xDC24V

01234567

01234567

321-1BH02-0AA05 6X 4


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Discrete Output Module Indicators

The indicators on most S7-300 output modules, shown in fi gure 7, illumi-nate green to indicate that the output is supplying a voltage. Some S7-300 output modules have built-in diagnostic capabilities. These modules include an SF indi-cator that illuminates red when an error is sensed by the module.

Figure 7. Discrete Output Module Indicators

Several models of the output modules are internally fused. Each fuse is used to fuse a channel group (i.e. 8 or 16 output lines). The SF indicator illuminates when a blown fuse is detected. The output module must be removed to replace the fuse.

OUTPUTSTATUS

INDICATORS

OUTPUTSTATUS

INDICATORS

SM322DO 16xDC24V0.5A

01234567

01234567

322-1BH01-0AA07 8X 6


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Power Supply Indicators

The PLC’s power supply converts AC power into DC power and provides the 24 VDC to power the CPU and I/O modules. It may also provide control power to sensors and actuators used by the system. The power supply may be mounted to the PLC chassis, such as the one shown in fi gure 8, or a separate unit.

Figure 8. DC Power Supply Indicators

Most power supplies have one of two types of status indicators to assist in trou-bleshooting system failures. The fi rst type shows that the power supply is operating correctly, delivering the correct output voltage and the load is within its capacity. Such indicators are typically labeled DC On, DC Power, or DC24V as shown in fi gure 8.

The second type of indicator is illuminated when the power supply is receiving AC power but does not confi rm the supply is operating correctly. Usually this type of indicator is labeled Power.

In applications using a large amount of 24 VDC power, a central power supply may be used for both the PLC and as control power to operate inputs and outputs. Often these installations will use a 24 VDC power bus similar to the three-phase AC power bus used in most industrial installations. The indicator for a central power supply is usually a 24 VDC lamp that illuminates when DC power is received at the station.

ONOFF

VOLTAGESELECTOR

120V

DC24V

PS3072A

307-1BA00-0AA0576

x

24VDCINDICATOR


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SKILL 1 USE S7-300 STATUS INDICATORS TO DETERMINETHE STATUS OF PLC OPERATION

Procedure Overview

In this procedure, you will observe the PLC and power supply status indicators as the mechatronics station goes through its power up routine. This will familiarize you with the operation of the conditions they represent.

1. Locate a mechatronics station. 2. Verify that this station has been separated from any other stations. If it has

not, proceed to Step 3 to separate it from the other stations. If it has, then proceed to Step 4.

3. Perform the following substeps to separate the station from the other stations.

A. Verify that the station is power cord has been removed from the wall outlet.

B. Remove the adjoining station’s power cord at the back of the station if necessary.

Figure 9. Adjoining Power Cord Removed (Shown from Rear of Station)

ADJOININGSTATION'S

POWER CORD

STATIONPOWERCORD


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C. Disconnect the station’s pneumatic hoses.

Figure 10. Pneumatic Hose (Shown from Rear of Station)

Figure 11. 9-Pin Cable

D. Disconnect the 9-pin to 9-pin cables from the station.

ADJOININGSTATION'S

PNEUMATICHOSE

9-PIN CABLE

9-PINCABLE


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E. Disconnect the USB cables from the station’s 87-FTS-S7 Fault Box Assembly to the assemblies in other stations.

F. Loosen the connecting fasteners that hold the work surfaces together by turning the thumbscrews CCW.

Figure 12. Connecting Fasteners

G. Remove the thumbscrew and set it aside.

H. Push the station away from the other stations to give yourself room to work.

4. Perform the following safety check before you begin working on the station. Make sure that you can answer yes to each item before proceeding.

YES/NO SAFETY CHECKOUT

Remove all obstructions from the work area

Check for signs of damage to the equipment

Wear tight fi tting clothing, roll up long sleeves, remove ties, scarves, jewelry, etc.

Tie up long hair

Remove any robot teach pendants from the work area

Locate the emergency stop button

Ensure that safety glasses are worn by people in area

Ensure that all people are outside any work envelopes

Figure 13. Mechatronics Safety Check

TURNCCW


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5. Connect an air supply to the air manifold’s quick connect in the back of the station, as shown in fi gure 14.

Figure 14. Station Air Hose Attached to Compressed Air Supply

STATIONAIR

HOSE

COMPRESSEDAIR SUPPLY


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6. Plug the station’s electrical cord into a power outlet. If the power cord is not attached to the station, locate it in the back of the station and plug the female end into the station’s power plug under the work surface at the back of the station, as shown in fi gure 15. Then plug the other end into the wall outlet.

There will be no visual indication that power has been applied to the station. Plugging the power cord into the outlet brings power to the back of the station.

Figure 15. Station Power Cord Attached to Wall Outlet

7. Place the CYCLE SELECT switch in the MANUAL position.

Figure 16. Mode Selector Switch Set to Manual Mode

STATIONPOWERCORD

STATION’SPOWERPLUG


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8. Remove the lockout/tagout device from the electrical power source. 9. Remove the lockout/tagout device from the pneumatic power source. 10. Turn on the air to the station by shifting the lever on the lockout valve. 11. Perform the following substeps to download a program to the mechatronics

station and observe the station indicators. For familiarization and troubleshooting purposes, you will use existing PLC

projects written for each mechatronics station. Use the table in fi gure 17 to select the program for your station.

STATION PROJECT

87-MS1 Feeder

87-MS2 Gauging

87-MS3 Indexing

87-MS4 Sorting and Queuing

87-MS5 Servo Robotic Assembly

87-MS6 Torquing

87-MS7 Parts Storage

Figure 17. Mechatronics Station Projects

A. Make sure the PC adapter cable is connected between the PC and the PLC.

B. Start and log in to the PC.

C. Start the SIMATIC Manager.

D. Open the proper program for your mechatronics station.

E. Download the program to the PLC.

F. Place the mechatronics station ON/OFF power switch in the OFF position.


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12. Perform the following substeps to power up the mechatronics station in a step-by-step fashion to observe the PLC status indicators during the power up routine.

The PLC’s input indicators and output indicators are shown in fi gure 18.

Figure 18. PLC and I/O Status Indicators

A. Observe the PLC, power supply, and I/O status indicators and record their status in the space provided.

Observation ________________________________________________

As expected, you should have observed that all indicators are turned off because the main power switch is turned off. However, other conditions can cause a loss of incoming power. Therefore, any time you observe no indicators of any type illuminated, suspect the main power switch or disconnect.

B. Place the PLC mode switch in the STOP position.

C. Place the mechatronics station ON/OFF power switch in the ON position.

PLCINDICATORS

PLCMODE

SWITCH

INPUTINDICATORS

OUTPUTINDICATORS


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D. Observe the PLC, power supply, and I/O status indicators and record their status in the table of fi gure 19.

MODULE INDICATOR STATUS

Processor

SF

BF

DC5V

FRCE

RUN

STOP

Input Modules Input Status

Output Modules Output Status

Power Supply DC ON

Figure 19. PLC Status Indicators in STOP Mode

You should have initially observed all of the processor indicators illu-minating as the PLC went through its power up sequence. After several seconds, the DC5V should have been green and the STOP indicator should have been amber.

The DC OK indicator on the power supply should have illuminated green when power was applied to the station.

These are normal indications on power up with the mode switch in the STOP position.

Because of small variations in S7-300 processor fi rmware, you may have observed the SF (system fault) indicator was red. With the processor in the stop mode, some elements of the power up routine were not executed. The fault will clear in the next substep.

Processor faults will be discussed in a future LAP.

E. Place the PLC mode switch in the RUN position.


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F. Observe the PLC, power supply, and I/O status indicators and record their status in the table of fi gure 20.


Processor

SF

BF

DC5V

FRCE

RUN

STOP



Power Supply DC ON

Figure 20. PLC Status Indicators in RUN Mode

You should have observed the processor STOP indicator turned off imme-diately, the RUN indicator fl ashed green for a few seconds then turned green. The DC5V and power supply indicators stayed green during the transition from stop to run mode. Input status indicators that were illumi-nated in the stop mode should be illuminated in the run mode.


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13. Perform the following substeps to observe the output status indicators.

A. Verify that the EMERGENCY STOP button is pulled out.

B. Press and release the OUTPUT POWER pushbutton.

This energizes the MCR circuit and applies control power to the output modules.

C. Observe the PLC, power supply, and I/O status indicators and record their status in the table of fi gure 21.


Processor

SF

BF

DC5V

FRCE

RUN

STOP



Power Supply DC ON

Figure 21. PLC Status Indicators in Output Power Applied

You should have observed that the processor and power supply indicators were unchanged. You should have also observed that one or more output status indicators illuminated.

This is the normal indication for the processor, power supply, and I/O status indicators when the PLC system is running.

14. Perform the following substeps to power down the mechatronics station.

A. Place the mechatronics station ON/OFF power switch in the OFF position.

B. Perform a lockout/tagout on the system’s electrical power source.

C. Perform a lockout/tagout on the system’s pneumatic power source.

D. Close the PLC program and the SIMATIC Manager.

E. Power down the PC.


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SEGMENT 1 SELF REVIEW

1. _______________ is the process of fi nding the cause or fault of a machine malfunction.

2. Because machine downtime is so expensive for a manufacturer, most maintenance personnel in manufacturing plants usually only perform ________ level troubleshooting.

3. The _______________ is an industrially hardened computer.

4. As _____________ and _____________ increase in PLC applications, so does the number of faults associated with them.

5. One of the tools the PLC provides to help monitor and troubleshoot the system are ______ or diagnostic indicators.

6. The indicators on most S7-300 input modules illuminate green to indicate that the input is receiving a(n) _____________.


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SEGMENT 2MECHATRONICS POWER SUPPLY TROUBLESHOOTING

OBJECTIVE 4 DESCRIBE THE OPERATION OF A MECHATRONICS POWER SUPPLY CIRCUIT

The PLC system requires DC operating power for the processor module and any peripheral modules (input, output, and communication). This power may be provided by a brand specifi c, rack-mounted power supply, or a separate, third party power supply. In addition, the PLC’s I/O devices require DC or AC control power. To provide both power requirements safely, a special power distribution circuit similar to that of fi gure 22, is recommended.

The power supply circuit uses a disconnect switch to remove all incoming AC power to the system. This affects both the operating power for the PLC as well as control power for the system’s input and output devices. Turning the discon-nect switch on provides AC to the PLC’s power supply and control power to the system’s input devices.

A master control relay (MCR) circuit is used to provide control power to the system’s output devices. Momentarily pressing the pushbutton energizes and seals in the circuit’s MCR. Another contact on the MCR provides control power to the PLC’s output devices.

The MCR circuit provides an emergency stop, or E-stop function to shut down the machine in an emergency by turning off the PLC system’s output power. Although a second set of contacts could be added to disable power to the input devices, it is more common to put the contacts on only the output side so that the inputs can remain energized for troubleshooting.


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Figure 22. Grounded AC Power Distribution System with Master Control Relay

The power distribution circuit shown in fi gure 22 is based upon grounding the circuit. This circuit can also be connected without grounding it, as shown in fi gure 23. This circuit would be used if the plant’s power distribution system is a delta confi guration. In this circuit, ground fault indicators are used to determine if the circuit has become grounded.

L1 L1

L2 L22FU

3FU

1FU

L3 L3

X2

H2

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X1

H4

H3

INCOMINGAC

TO MOTORSTARTERS

DISC

USE ANY NUMBEROF E-STOP SWITCHES

IN SERIES START

MCR

MCR

PLCPOWER SUPPLYL1 N

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GND2

INPUTDEVICE

OUTPUTDEVICEINPUT

MODULEWIRING

OUTPUTMODULEWIRING

EQUIPMENTGROUNDING

CONDUCTORS

BACK PANELGROUND BUS

STEP-DOWNTRANSFORMER

GROUNDINGELECTRODECONDUCTOR

TO GROUNDINGELECTRODE

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1. TO MINIMIZE EMI GENERATION, A SUPPRESSION NETWORK SHOULD BE CONNECTED.

2. FOR A POWER SUPPLY WITH A GROUNDABLE POWER SUPPLY CHASSIS, THIS REPRESENTS CONNECTION TO THE POWERSUPPLY CHASSIS ONLY. FOR A POWER SUPPLY WITHOUT A GROUNDABLE POWER SUPPLY CHASSIS, THIS REPRESENTSCONNECTION TO THE GND TERMINAL.

3. IN MANY APPLICATIONS, A SECOND TRANSFORMER PROVIDES POWER TO THE INPUT CIRCUITS AND POWER SUPPLIES FORISOLATION FROM THE OUTPUT CIRCUITS.

MCR


28

Figure 23. Ungrounded AC Power Distribution System with Master Control Relay

0

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L1 L1

L2 L22FU

3FU

1FU

L3 L3

X2X1

INCOMINGAC

TO MOTORSTARTERS

DISC


IN SERIES START

MCR

MCR

MCR

PLCPOWER SUPPLYL1 N

1

1

GND2

INPUTDEVICE

OUTPUTDEVICE

INPUTMODULEWIRING

OUTPUTMODULEWIRING

MCR

TO DC I/ODEVICES

CONNECTWHEN

APPLICABLE

EQUIPMENTGROUNDING

CONDUCTORS




SYSTEM

+ -


USER DCSUPPLY

H2

H1 H4

H3

3

FUSE FUSE





29

Many new installations use 24 VDC control power systems. The lower voltage has several advantages including faster switching times and a safer working envi-ronment for technicians. Most use a grounded system similar to the one shown in fi gure 24. The power to the output modules is controlled through a MCR system to remove power from outputs in case of an emergency.

Figure 24. 24 VDC Control Power System

L1 L1

L2 L22FU

3FU

1FU

L3 L3

X2

H2

H1

X1

H4

H3

INCOMINGAC

TO MOTORSTARTERS

DISC


IN SERIES START

MCR

MCR

L1 NPLC

POWER SUPPLY

1

GND2

INPUTDEVICE

OUTPUTDEVICE

INPUTMODULEWIRING OUTPUT

MODULEWIRING

EQUIPMENTGROUNDING

CONDUCTORS





SYSTEM

3

OUTPUT

DC-SOURCE

0

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3 45 67 89 10

11 1213 14

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15 DC COM

VOC

INPUT

DC-SINK

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567

89

10 1112

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DC COM

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FUSE




MCR


30

OBJECTIVE 5 DESCRIBE HOW TO TROUBLESHOOT MECHATRONICS POWER SUPPLY PROBLEMS

The technician responds to manufacturing line failures by identifying the symptoms and formulating possible causes and remedies. For example, the tech-nician who observes all machine and control indicators are off and that nothing is operating may conclude that a power failure has occurred. The failure could involve the entire production fl oor or a single PLC/control power supply.

PLC power supply problems are easy to troubleshoot compared to many systems because the symptom is found through the entire system or an entire subsystem. PLC power failures typically show one of two symptoms:

• All PLC indicators are off• All output indicators are off

All PLC Indicators are Off

This could be caused by a failure in the main power circuit or a bad power supply. In either case, none of the PLC modules will receive power.

First, check the main power disconnect to make sure it is on. If it is on, measure the voltage at the DC power supply’s input terminals, L1 and N, as shown in fi gure 25. This should match the incoming power supply. If it does, the problem is in the power supply module. If it does not, the problem is in the main power lines, the control transformer, or the wiring from the main power lines.

Figure 25. Testing Incoming Power to a Power Supply

COM

AC VOLTS

V

+V +V -V -V

24 VDCPOWER SUPPLY

N L

DCOK


31

All Output Indicators are Off

In this instance, the PLC and possibly some input status indicators are on but none of the output status indicators are illuminated. Press the Control Power or Output Power button to energize the MCR, then check for control voltage at the output modules. Control power should be measured at the L+ to M terminals, as shown in fi gure 26.

Figure 26. Measuring Voltage to an Output Module

01234567

DI+2

IN

01234567

DO+0

OUT

01234567

DI+0

IN

01234567

DI+1 DO+0

01234567

CPU314C-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIEMENS

X1 MPI X2 DP

V2.0.11

COM

24 VDC

V

2L

3L

+

+

1L+


32

OBJECTIVE 6 DESCRIBE HOW TO TROUBLESHOOT A MECHATRONICS POWER SUPPLY

Generally, if a mechatronics power supply indicator is on, the supply is oper-ating correctly. If the indicator is off, use the following six-step procedure to trou-bleshoot the power supply:

Step 1: Verify that the power supply is turned on

Step 2: Verify that the line voltage is within the specifi ed range

Step 3: Verify that the voltage selector switch is in the correct position

Step 4: Cycle power to the power supply

Step 5: Confi rm that the load is within the output rating of the power supply

Step 6: Isolate the load from the power supply and test for shorts and overloads

Step 1: Verify that the Power Supply Is Turned On

Many power supplies have an on/off power switch to shut down the supply for troubleshooting systems powered from the DC output connection. Other manufac-tures claim the switch is a potential failure point and omit the switch.

If it has one, verify that the power switch is turned on.


33

Step 2: Verify that the Line Voltage Is within the Specifi ed Range

Most modern power supplies have monitoring circuits that protect the supply in case of variations in the AC power applied to the supply. The acceptable voltage is usually specifi ed over a range, such as 100 to 120 VAC. Voltages below or above the range cause the power supply to shut down to prevent damage to its circuitry.

Measure the incoming voltage at the power supply AC terminals, typically labeled L1, L2, and GND, or may be abbreviated L, N, and the ground symbol, as shown in fi gure 27. The incoming power connection is frequently located behind a protective cover to prevent short circuits and accidental contact with potentially lethal power.

Figure 27. Power Supply Terminals

Step 3: Verify that the Voltage Selector Switch Is in the Correct Position

Many power supplies are designed to operate on more than one incoming power voltage such as 120/220 VAC. This switch is normally set at installation and not changed. The technician should verify that the switch is in the correct position when installing a new power supply.

Make sure the switch position has not accidentally been changed.

If the incoming voltage is missing or not correct, troubleshoot the power distri-bution system including circuit breakers and fuses that supply power to the station.

N L


34

Step 4: Cycle Power to the Power Supply

Power supplies that contain internal protection circuitry can shut down on an incoming power low voltage dip or a high voltage spike. The supply also shuts down if the load exceeds the supply’s ratings or the supply becomes overheated. Cycling power to the supply clears the fault and places the supply back in operation.

Different manufacturers recommend leaving the power off for a specifi ed time to allow for cooling. The interval may be from 30 seconds to several minutes depending on the capacity of the supply. If the power supply indicator does not illuminate, the supply has failed, it is overloaded, or one or more of the loads connected to the supply may have a problem.

Step 5: Confi rm that the Load Is within the Output Rating of the Power Supply

In addition to the incoming voltage level, power supplies are rated for how much current they can deliver at the output voltage. The rating is displayed on the data plate or label for the supply. For example, a typical supply to power a PLC and limited I/O devices may be rated for 5 amps at 24 VDC. The supply can deliver that current continuously without overheating and may supply more current for a short time before shutting down the supply on an over current fault.

Calculate the current demand of all loads that will be connected to the power supply. If the demand is greater than the capacity, replace the supply with a larger one or install a redundant power supply.

Step 6: Isolate the Load from the Power Supply and Test for Shorts and Overloads

A power supply that shuts down when the load is within its rated capacity may have a load connected that is either shorted or drawing more current than is normal. To isolate the failure to the power supply or the load, turn off power to the supply and disconnect it from the load, then re-apply power. If the power indicator remains off, the power supply has failed and must be replaced.

If the indicator turns on, a component in the load has failed. Reconnect the loads one at a time, re-applying power after connecting each one until the power indicator fails to illuminate. The last load connected is probably the one that has failed.

The six-step troubleshooting procedure is represented in the fl owchart shown in fi gure 28.


35

Figure 28. Power Supply Troubleshooting Chart

BusPOWERSUPPLY

LEDON?

YES

NO

VERIFY THAT POWERSUPPLY SWITCH IS ON

ISOLATE POWER SUPPLYFROM THE LOAD

RE-APPLY POWER

STATIONPOWERSUPPLYLED ON?

NO

YES

REPLACE POWERSUPPLY MODULE

POWER IS OK,PROBLEM IS ELSEWHERE

CALCULATE POWER SUPPLYLOADS AND COMPARE WITH

OUTPUT RATING OF UNIT

ARE LOADSWITHIN POWER

SUPPLYRATING?

YES

NO

RECONNECT LOADSINDIVIDUALLY TESTING

EACH ONE

INSTALL LARGEROR REDUNDANTPOWER SUPPLY

POWERSUPPLY LED

OFF

REPLACE STATIONPOWER SUPPLY

TEST NEXTMODULENO

YES

IS LINEVOLTAGEWITHIN

RANGE?NO

YES

CHECK INCOMINGPOWER, DISCONNECT

POWER SUPPLYTROUBLESHOOTING

FLOWCHART

STATIONPOWERSUPPLY

LEDON?

ISBUS PSINPUT

24 VCD?

TROUBLESHOOT INPUTWIRING, STATIONPOWER SUPPLYYES NO

REPLACE BUSPOWER SUPPLY

NO

YES


36

SKILL 2 TROUBLESHOOT A MECHATRONICS POWER SUPPLY

Procedure Overview

In this procedure, you will troubleshoot a mechatronics power supply. You will insert a fault into the power supply using the station’s fault insertion system. This will teach you how to recognize the symptoms of a power supply failure, use a troubleshooting fl owchart, and correct the failure.

1. Obtain a mechatronics station and separate it from any other stations. Make sure any fi xtures or bins are installed for single-station operation.

2. Perform the following substeps to verify that the troubleshooting system is properly connected.

A. Examine the back of the station to determine if the 87-FTS Fault box assembly is installed and connected in the station, as shown in fi gure 29.

The fault box assembly is connected between the input and output devices on the mechatronics station for insertion of faults in the system to provide troubleshooting scenarios.

Faults for open and shorted circuits, and failed modules are created in FaultPro software and transferred to the fault box through a USB cable.


37

Contact your instructor if the fault box assembly is not installed, other-wise proceed to substep B.

Figure 29. 87-FTS Fault Box Assembly Connections

B. Verify that the PC adapter cable is connected between the PC and the PLC.






Tie up long hair






AMATROL

MECHATRONICS FAULT INSERTION

1 2 3 4 5

USER FAULTS

6 7 8 9 10

PLC PANEL OPERATOR STATION

I/O PORT 1

I/O PORT 1

I/O PORT 2 I/O PORT 3

I/O PORT 1 I/O PORT 1

FROM PLC

TO STATION

NEXTSTATION

A

POWERSUPPLY FAULT

PREVIOUSSTATION PC

B

87-FTS

PLCFAULTS

D

I/O PORT 1 I/O PORT 2 I/O PORT 3

FAULT BOXASSEMBLY

STATION'S DISCRETEI/O INTERFACE

START STOP CYCLESELECT

OUTPUTPOWER

RESET AUTOMANUAL

ON/OFF

EMERGENCY STO

P

870-PS731X-AAU

STATION'SOPERATOR INTERFACE

TO NEXTSTATION

TO PCUSB PORT


38

4. Power up the mechatronics station with electricity and air and turn on output power.

5. Perform the following substeps to download a project to the PLC and test the mechatronics station for proper operation.

For familiarization and troubleshooting purposes, you will use existing PLC projects written for each mechatronics station. Use the table in fi gure 31 to select the program for your station.

STATION PROJECT

87-MS1 Feeder

87-MS2 Gauging

87-MS3 Indexing



87-MS6 Torquing



A. Start and log in to the PC.

B. Start the SIMATIC Manager

C. Open the proper program for your mechatronics station.

D. Download the program to the PLC.

E. Place the PLC into the RUN mode.

F. Display OB1 and press the Monitor button on the tool bar to go online.

G. Turn the CYCLE SELECT switch to the RESET position, then to the AUTO position.

H. Place a valve component, compatible with the station you are using, at the input of the station.

I. Press and release the START pushbutton to start the cycle.

J. Verify that the station cycles through its functions correctly.

Contact your instructor if the cycle is not correct. 6. Perform the following substeps to familiarize yourself with the proper

operation of the station’s power supply.

A. Observe the status of the power supply indicator.

Indicator ___________________________________________(On/Off)

You should have observed that the indicator was illuminated.


39

B. Locate the rating data on the power supply. Record the information in the space provided.

Stations with an S7-315 processor use a Siemens power supply. The rating information is not listed on these power supplies.

Input voltage _________________________________________ (VAC)

Output voltage ________________________________________ (VDC)

Output current _______________________________________ (Amps)

The 87-MXx Mechatronics stations with S7-313 or S7-314 processors are equipped with one of two power supplies. One has an input voltage selector switch that is set for either 100-120 VAC or 200-240 VAC. This power supply provides 24 VDC at fi ve amps.

The second power supply does not have a voltage selector switch and can accept input voltages of 100-220 VAC. This supply provides 24 VDC at 3.2 amps.

C. Obtain a voltmeter and set it to measure your incoming power supply, such as 120 or 230 VAC.

D. Place the COM (black) meter probe on the N power supply terminal.

E. Place the V (red) meter probe on the L power supply terminal.

Figure 32 shows proper placement of the meter probes.

Figure 32. Meter Set Up to Measure Power Supply Incoming Power

COM

AC VOLTS

V

+V +V -V -V

24 VDCPOWER SUPPLY

N L

DCOK

BLACKPROBE

REDPROBE


40

F. Record the voltage measurement.

Voltage __________________________________________ (Volts AC)

Your measurement should have approximately matched your incoming power supply.

G. Change the voltmeter setting to measure 24 VDC.

H. Place the black meter probe on the -V power supply terminal.

I. Place the red meter probe on the +V power supply terminal.

J. Record the voltage measurement.

Voltage __________________________________________ (Volts DC)

You should have measured 24 VDC.

These measurements are the normal measurements for the power supply. 7. Perform the following substeps to simulate a power failure to the mechatronics

station.

A. Obtain copies of the Power Supply Troubleshooting Flowchart and the Troubleshooting Process Recording Chart from your instructor.

B. Place the mechatronics station ON/OFF switch in the OFF position.

The On/Off switch is a circuit breaker. Placing the switch in the off posi-tion simulates a tripped circuit breaker.


41

C. Perform the fi rst step in the troubleshooting fl ow chart. Record the step and result in the Troubleshooting Process Recording Chart.

Your chart should look similar to the one in fi gure 33.

Examining the PLC’s status indicators, you should notice that all station indicators are off. This indicates that the power supply is a good place to start troubleshooting.

In this instance, the power supply indicator was off, meaning the power supply is not operating. The next few steps will determine whether the incoming power has failed, the supply has failed, or if there is an overload condition in the devices connected to the power supply.

TROUBLESHOOTING PROCESS RECORDING CHART

Symptom Observed: All PLC and station indicators off

Step Check Made Result

1 Power Supply LED off? Yes

2

3

4

5

6

7

Remedy:

Figure 33. Troubleshooting Process Recording Chart


42

D. Perform the next step in the troubleshooting fl ow chart. Record the step and result in the Troubleshooting Process Recording Chart.






2 Verify that power supply switch is on N/A

3

4

5

6

7

Remedy:


Some power supplies used on the mechatronics stations do not have an on/off switch. However, the next power supply you troubleshoot may have a switch so it is a good habit to check for the switch and its status.

If your system uses an S7-315 processor, the power supply is located next to the PLC processor. The power supply should have a power switch.


43

E. Perform the next step in the troubleshooting fl owchart. Record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 35.






3 Verify that the line voltage is within specifi ed range

No, 0 VAC

4

5

6

7

Remedy:


This check is made by measuring the incoming AC voltage at the L and N terminals of the power supply. In this instance, the measurement was 0 VAC, indicating the power supply is not receiving power.

If you are using an S7-315 processor, the test points are located behind the power supply’s door. Lift up the bottom of the door to open it.


44

F. Perform the next step in the troubleshooting fl owchart. Record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 36.







No, 0 VAC

4 Check incoming power, disconnect Switch off

5

6

7

Remedy: Place ON/OFF switch in the ON position


The No answer directed you to check the incoming power and the discon-nect to the power supply.

G. Return the ON/OFF switch to the ON position.

The power supply DC OK indicator should illuminate and the PLC should begin its power up sequence.


45

8. Perform the following substeps to open and log in to FaultPro software. FaultPro induces faults into the mechatronics station to provide troubleshooting

scenarios. Your instructor should have created a user account for you and given you a username and password to open the software. In the steps that follow, you will use this software to insert another type of power fault.

A. Minimize the Step 7 software but do not close it.

B. Locate the FaultPro Student icon, shown in fi gure 37, on the PC desktop.

Figure 37. FaultPro Student Icon

C. Double-click the icon to open the software.

If the FaultPro Student icon is not found on the desktop, the software may be opened by clicking Start on the taskbar followed by All Programs, FaultPro, and then Student.

A splash screen should open followed by the Student Login window shown in fi gure 38.

Figure 38. FaultPro Student Login Window


46

D. Enter your login ID and Password then click the OK button.

Contact your instructor if you don’t know or have forgotten your login ID and/or password.

The Student Options window shown in fi gure 39 should open.

Figure 39. Fault Pro Student Menu

SINGLE FAULTMODE

BUTTON


47

9. Perform the following substeps to insert a power fault into the mechatronics station.

Faults are inserted into the mechatronics stations in two ways: Single Fault mode or Random Fault mode.

In Single Fault mode, the user manually enters faults into the system. This mode helps the user by familiarizing him or her with the symptoms of a specifi c fault and how to troubleshoot the fault. You will use this mode for the remainder of this LAP.

In Random mode, faults are predefi ned and entered into the system automatically. You will use this function in a later LAP.

A. Open the Class folder, if required.

B. Open the LAP 1: Introduction to Mechatronics Troubleshooting option.

C. Select the Skill 2: Troubleshoot a Mechatronics Power Supply option.

D. Click the Single Fault Mode button.

The Single Fault Mode window shown in fi gure 40 should open.

Figure 40. Single Fault Mode Window

ENTERFAULTFIELD

STATIONSELECT

DROP LIST


48

The software should automatically detect the connected station and list it in the station select drop list.

FaultPro identifi es the mechatronics stations by on-station coding and uses that information to load the fault sets for the stations found. This prevents the user from entering a fault not supported by the station or one that could cause damage.

E. Select your station on the drop-down list if it is not already selected.

The stations found are listed in the select station drop list shown in fi gure 40. The station names are shown in the table of fi gure 41. The station name should match the name of the station you are working on. If they do not match, check the USB network.

STATION FAULTPRO TEMPLATES

87-MS1 1 - Feeding

87-MS2 2 - Gauging

87-MS3 3 - Indexing

87-MS4 4 - Sorting

87-MS5 5 - Assembly

87-MS6 6 - Torquing

87-MS7 7 - Storage

Figure 41. Mechatronics Stations and FaultPro Templates

F. Place the cursor on the Enter Fault: fi eld and type 53.

G. Click the Enter button to the right of the fi eld to activate the fault.

The dialog should change to show the fault is active, as shown in fi gure 42.

You should have noticed the status of the mechatronics PLC changed.

Figure 42. Dialog Showing Fault 53 Archive

FAULTACTIVE

CLEARFAULT

BUTTON

ENTERBUTTON


49

10. Perform the following substeps to troubleshoot the power supply fault.

A. Obtain copies of the Power Supply Troubleshooting Flowchart and the Troubleshooting Process Recording Chart from your instructor.

B. Observe the PLC symptom and record it in the space provided.

Symptom __________________________________________________

You should have observed that all indicators on the PLC and station turned off.

C. Perform the fi rst step in the troubleshooting fl owchart. Record the step and result in the Troubleshooting Process Recording Chart.


Several faults could cause the power supply LED to turn off. The trouble-shooting fl owchart will direct you step by step to determine the cause.





2

3

4

5

6

7

Remedy:



50

D. Perform the next step in the troubleshooting fl owchart, record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 44.

NOTE

Only some power supplies used with the stations have an on/off switch.






3

4

5

6

7

Remedy:


The power supply on the mechatronics station does not have an on/off switch. However, the next power supply you troubleshoot may have a switch so it is a good habit to check for the switch and its status.


51

E. Perform the next step in the troubleshooting fl owchart, record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 45.







Yes, incoming VAC

4

5

6

7

Remedy:


Measure the incoming voltage using the procedure and data obtained in Step 6. You should have measured approximately the incoming VAC.

The incoming voltage is in the correct range. This eliminates the main power as a source of the failure and eliminates an under or over voltage shutdown as the cause of the problem.


52

F. Perform the next step in the troubleshooting fl owchart, record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 46.







Yes, incoming VAC

4 Isolate power supply from load; re-apply power

Done

5

6

Remedy:


This step determines if the failure is in the power supply or the load. Depending on the type and connection of the power supply, you may have to remove modules from a chassis or remove wires from output terminals. For the purpose of this skill, assume the power supply has been discon-nected from the load.


53

G. Perform the next step in the troubleshooting fl owchart, record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 47.







Yes, incoming VAC


Done

5 Power supply LED off? Yes

6

Remedy:


The power supply has incoming power applied, the load has been removed, and the DC OK indicator remains off. The problem is with the power supply. Either the unit has failed or it did not have enough time to cool to reset an over temperature fault. If the power supply is hot to the touch, check for excess dust blocking cooling vents or some other condition that could prevent it from receiving an adequate fl ow of cooling air.


54

H. Perform the next step in the troubleshooting fl owchart, record the step and result in the Troubleshooting Process Recording Chart. Your chart should look similar to the one in fi gure 48.







Incoming VAC


Done

5 Power supply LED off? Yes

Remedy:Repair or replace power supply


The troubleshooting process is completed by repairing or replacing the power supply. In this example, Fault 53 simulates a power supply failure.

11. Perform the following substeps to clear the fault and verify the correct operation of the power supply.

A. Click the Clear Fault button in the left-hand window of the FaultPro dialog.

The power supply indicator should illuminate and the PLC will go through its start up routine.

B. Press the Output Power pushbutton to restore control power to the output module.

C. Turn the CYCLE SELECT switch to RESET then back to AUTO to reset the station.

D. Verify the station will process the component properly.

You have succeeded in troubleshooting a mechatronics station power supply.

E. Click the Exit button to return to the Student Options window.

F. Click the Logout button to close the Student Options window.

G. Click the Exit button to close the FaultPro software. 12. Power down the mechatronics station and shut down the PC.


55


1. The PLC system requires ___________ operating power for the processor module and any peripheral modules.

2. A(n) __________________ circuit provides control power to the system’s output devices.

3. If either of the following conditions exists, it is very likely that there is a(n) ______________ supply problem: all PLC indicators are off, or all I/O status indicators are off.

4. The fi rst step in troubleshooting a power supply problem is to verify that the ___________________ is on.

5. To isolate a power supply problem to the power supply or the load, turn off the power and _________________ the load and apply power to the supply.


56

SEGMENT 3MECHATRONICS INPUT TROUBLESHOOTING

OBJECTIVE 7 DESCRIBE HOW TO TEST MECHATRONICS DISCRETE INPUT DEVICES

In a mechatronics system, discrete input devices send an on or off signal to the PLC input module depending on the state of its sensing element and the wiring of contacts connected to the element. The most basic discrete input device is an elec-tromechanical switch, such as a pushbutton.

Devices such as pushbuttons, selector switches, and limit switches are called two-wire devices because, as fi gure 49 shows, one wire connects the control power source to the switch and a second wire connects the switch to the input module.

Figure 49. Two-Wire Input Device Operation

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

16 POINTOUTPUTMODULE

DC POWERSUPPLY

+

-

STATUSINDICATORTURNS ONAND OFF

PUSHBUTTON


57

Other discrete input devices use electronic sensors instead of mechanical ones. Devices such as the proximity switch, shown in fi gure 50, are called three-wire devices because, in addition to the control power and input module wires, a third wire connects to the power supply common to complete the power circuit for the on-board electronics that operate the device.

Three-wire devices include inductive and capacitive proximity switches, photo switches, and other electronic sensors. Although the method each type of sensor uses to sense the object varies, a transistor output is usually used to send a signal to the PLC. This transistor output acts as a switch that sends a signal to be sent to the PLC.

Figure 50. Three-Wire Input Device Operation

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

PS3072A

SIMATICS7-300

DC24V

307-1BA00-00A0

120V

VOLTAGESELECTOR

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

CPU315-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIEMENS

TO INPUTTERMINAL POWER

COMMON

+24 VDC

DCCOM

INPUTTERMINAL

SENSOR


58

The following steps show the general method used to test discrete input devices.

Step 1: Observe the operation of the PLC input indicator

Step 2: Check the voltage at the PLC input terminal

Step 3: Test the input device and its wiring

Step 1: Observe the Operation of the PLC Input Indicator

The fi rst test is to operate the input device and observe the PLC’s input indi-cator. If the input status indicator turns on and off as the input device is operated, the input device is operating properly, as shown in fi gure 51.

Figure 51. Testing an Input Device with the Indicator Lights

If the terminal’s status indicator does not turn on when the input device is oper-ated, there is a problem with the input device itself, input device wiring, or the I/O power.

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

INPUTMODULE

CONTROLPOWER

+

-

STATUSINDICATORTURNS ONAND OFF

PUSHBUTTON


59

Step 2: Check the Voltage at the PLC Input Terminal

If the indicator light does not turn on, the next step is to measure the voltage at the terminals.

The voltage test is performed by attaching the leads of a multimeter to the common and input terminals of the input module, as shown in fi gure 52. If the input device and interface wiring are working, the voltage will change as the device operates. How the voltage changes depends upon the type of input module.

The multimeter should display a high voltage when the input device is closed if the module uses an active high type input, as shown in fi gure 52.

Figure 52. Meter Connections for Testing an Active Hi Input Module

COM

24 VDC

V

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

16 POINT INPUT MODULE

CONTROLPOWER

+

-

PUSHBUTTON


60

The multimeter will display a low voltage (near zero) when the input device is closed if the module is an active low type, as shown in fi gure 53.

Figure 53. Switch Closed Voltage Low, Active Low Input Module

COM

0 VDC

V

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

16 POINT INPUT MODULE

CONTROLPOWER

+

-

PUSHBUTTON


61

Step 3: Test the Input Device and Its Wiring

If a voltage change is not measured at the terminals, the last step is to check the wiring, input device, and the power to the input device.

Two-wire devices, such as pushbuttons and limit switches, can be tested out-of-circuit using a continuity test. In a continuity test, the device is removed from the circuit completely and tested with the resistance or continuity settings of the multimeter. The multimeter should indicate zero ohms when the switch is closed and infi nity when it is opened, as shown in fi gure 54.

Figure 54. Continuity Testing of an Input Device

COMV

0

COMV

0

COMV

PRESSEDNOT

PRESSED

O.L.


62

Because of the power requirements for the electronic circuitry, three-wire devices are often tested while attached to the PLC and under power. Precautions must be taken to prevent unexpected movement of the system, which could injure workers or damage the machine. Placing the PLC into program mode and removing control power from output modules are the minimum steps to take. Depending on the system, pneumatic and hydraulic devices may need to be locked out and blocked in position before removing power from the output modules.

Once the system has been made secure, three-wire devices are tested using the same steps as a two-wire device: observe the PLC input indicators, check the voltage at the PLC input terminal, and test the input device and its wiring.

The technician must be aware of how the device is triggered. For example, a capacitive proximity switch can sense non-ferrous material while an inductive proximity switch cannot. Magnetic reed switches, which may be either two- or three-wire, are actuated by a magnet.

To help in troubleshooting, the majority of three-wire devices and many two-wire devices have indicators that illuminate when the switch is actuated and send a “closed” signal to the PLC. For example, fi gure 55 shows indicators on magnetic reed switches attached to an air cylinder. When the piston is within the sensing range of the switch, the switch turns on the indicator and sends a closed signal to the PLC.

The switches are tested by manually operating the solenoid valves that control the cylinder while observing the indicator. An indicator that turns on and off when the cylinder is actuated confi rms the presence of control power and proper opera-tion of the switch.

Figure 55. Indicators on Discrete Input Devices

INDICATOROFF

INDICATORON

PISTON


63

SKILL 3 TEST MECHATRONICS DISCRETE INPUT DEVICES

Procedure Overview

In this procedure, you will test mechatronics electromechanical and three-wire input devices when they are operating properly and when faults have been inserted into the system. This will familiarize you with testing discrete input devices.

1. Perform the following substeps to prepare a mechatronics station to test discrete input devices.

A. Obtain a mechatronics station and set it up for single-station operation.

B. Verify that the 87-FTS Fault Box is installed and connected to the station.

C. Verify that a USB cable connects the fault box to the PC.

D. Verify that the PC adapter cable is connected between the PC and the PLC.






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Figure 56. Mechatronics Safety Checkout



64


A. Start and log on to the PC.

B. Start the SIMATIC Manager.

C. Open the proper program for your mechatronics station.

Figure 57 shows the programs for the mechatronics stations.

STATION PROJECT

87-MS1 Feeder

87-MS2 Gauging

87-MS3 Indexing



87-MS6 Torquing



D. Download the program to the PLC.

E. Place the PLC into the RUN mode.

F. Display OB1 and press the Monitor button on the tool bar to go online.

G. Turn the CYCLE SELECT switch to the RESET position then to the AUTO position.

H. Place a valve component, compatible with the station you are using at the input of the station.

I. Press the START pushbutton to start the cycle.

J. Verify that the station cycles through its functions correctly.

Contact your instructor if the cycle is not correct. 5. Perform the following substeps to familiarize yourself with the proper

operation of a discrete input device.

A. Place the PLC into the STOP mode.

You will be actuating inputs, which could cause unexpected movement. Stopping the PLC prevents the ladder logic from turning on outputs.

B. Press the EMERGENCY STOP button.

The Emergency Stop button opens the MCR circuit and removes control power from the output module.

C. Remove all valve components from the station. If you are using the 87-MS5 station, do not remove the knobs and screws for the 87-MS5 station. Be sure to remove all spools from the 87-MS5 station.


65

D. Observe the input module indicator for I1.2 (I1.3 for 87-MS5) and record your fi ndings in the space provided.

Input Indicator: _____________________________________(On/Off)

You should have observed the indicator was illuminated.

E. Obtain a multimeter and set it to measure 24 VDC.

Figure 58. I/O Terminals

F. Put the COM (black) probe on any of the M terminals.

G. Put the V (red)probe on the I1.2 (I1.3 for 87-MS5) terminal.

Use fi gure 58 to locate the terminals on the I/O modules.

If you are using a 315 processor with separate I/O modules, input I1.2 is in the I/O module immediately to the right of the processor. The terminal corresponding to input I1.2 is located in the bottom row of inputs, and uses indicator 2.

Measure the voltage at the input terminal on the PLC input module. Record the voltage in the space provided.

Input Voltage: ________________________________________ (VDC)

You should have recorded 24 VDC.

01234567

DI+2

IN

01234567

DO+0

OUT

01234567

DI+0

IN

01234567

DI+1 DO+0

01234567

01234567

DI+0

IN

01234567

DI+1

INPUTSI1.0 - I1.7

CPU314C-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIEMENS

X1 MPI X2 DP

V2.0.11

4M

I1.2

1M 3M

I1.3


66

H. Using the table in fi gure 59 as a reference, manually operate the solenoid valve that affects the input device.

You will actuate the input device by manually operating the solenoid valve associated with the device. The names in the Solenoid column of fi gure 60 are the same as the labels on the valves.

STATION SOLENOID

87-MS1 Q4.5 Feed Part Extend

87-MS2 Q4.5 Part Reject Extend

87-MS3 Q4.5 Transfer Cylinder

87-MS4 Q4.5 Sorting Cylinder

87-MS5 Q4.5 Spool Insertion

87-MS6 Q4.5 Clamp Extend

87-MS7 Q4.5 Pickup Extend


I. While the cylinder is extended, observe the I1.2 (I1.3 for the 87-MS5) indicator on the input module. Record your fi ndings in the space provided.


You should have observed the indicator turned off when the cylinder was extended.

J. While the cylinder is extended, measure the voltage at the I1.2 (I1.3 for the 87-MS5) terminal on the input module. Record your measurement in the space provided.

Input Voltage: ________________________________________ (VDC)

You should have recorded 0 VDC.

You have successfully tested an input device when it is operating correctly.


67

6. Perform the following substeps to insert an open-type fault into the input device at input I1.2 (I1.3 for 87-MS5).

A. Open the FaultPro software and log in using your login ID and password.

B. Open the Class folder, if required.

C. Open the LAP 1 option.

D. Select the Skill 3 option.

E. Click the Single Fault Mode button.

F. Select the appropriate station.

G. Place the cursor on the Enter Fault: fi eld and type 6 (8 for the 87-MS5).

H. Click the Enter button to the right of the fi eld to activate the fault. 7. Perform the following substeps to test input I1.2 (I1.3 for the 87-MS5).

A. Observe the input module indicator for I1.2 (I1.3 for the 87-MS5). Record your fi ndings in the space provided.

Input Indicator: ______________________________________(On/Off)

You should have observed the indicator was off.

B. Measure the voltage at input terminal I1.2 (I1.3 for the 87-MS5). Record your measurements in the space provided.

Input Voltage: ________________________________________ (Volts)


C. Manually operate the solenoid valve that affects the input device and observe the indicator for input I1.2 (I1.3 for the 87-MS5). Record your fi ndings in the space provided.


You should observe that the indicator remains off.

D. Manually operate the solenoid valve and measure the voltage at input I1.2 (I1.3 for the 87-MS5). Record your measurements in the space provided.



From the observations and measurements, you can determine the signal from the input device is not arriving at the input module. This could be caused by one of three conditions: the control power supply has failed, the input device has failed, or the wiring to or from the device has failed.

Observe indicators for other inputs. If any are illuminated, the control power supply is operating. Measure the voltage in and out of the input device to determine if it is operating.

Fault 6 (Fault 8 for the 87-MS5) emulates a failed input device. 8. Click the Clear Fault button on the FaultPro dialog.


68

9. Observe the input module indicator for I1.2 (I1.3 for the 87-MS5).

Input Indicator: _________________________________________(On/Off)

You should have observed the indicator was on. 10. Perform the following substeps to insert a shorted fault into the input device

at input I1.2 (I1.5 for MS5 and output Q4.7).

A. Place the cursor on the Enter Fault: fi eld and type 7 (11 for 87-MS5).

B. Click the Enter button to the right of the fi eld to activate the fault. 11. Perform the following substeps to test input I1.2 (I1.5 for the 87-MS5).

A. Observe the input module indicator for I1.2 (I1.5 for the 87-MS5). Record your fi ndings in the space provided.


You should have observed the indicator was on.

B. Measure the voltage at input terminal I1.2 (I1.5 for the 87-MS5). Record your measurements in the space provided.



C. Manually operate the solenoid valve that affects the input device and observe the indicator for input I1.2 (I1.5 for the 87-MS5). Record your fi ndings in the space provided.


You should observe that the indicator remains on.

D. Measure the voltage at Input terminal I1.2 (I1.5 for the 87-MS5). Record your measurement in the space provided.



From the observations and measurements, you can determine that the signal is always present at the input terminal. This could be caused by a shorted switch or a short in the input wiring.

E. Click the Clear Fault button on the FaultPro dialog.

F. Click the Exit button to return to the Student Options window.

G. Click the Logout button to close the Student Options window.

H. Click the Exit button to close the FaultPro software. 12. Power down the mechatronics station and shut down the PC. You have successfully tested mechatronics discrete input devices with and

without faults.


69

OBJECTIVE 8 DESCRIBE HOW TO TEST A DISCRETE INPUT MODULE

Siemens input modules usually fault to one of two conditions:• Condition 1: Input indicators illuminate, but information is not passed to the process image data table• Condition 2: Module shorts internally and drags power supply to ground

Condition 1: Input Indicators Illuminate, but Information Is Not Passed to the Process Image Data Table

If an input module’s input indicators verify the status of the input device connected to it, but it is suspected that the module is bad, testing is in order.

Operate the input device and observe the status of the input bit in the process image table or the instruction on the ladder diagram. If the module is sending the signal to the processor, the data bit should change from 0 to 1 in the PLC’s process image table and the ladder logic instruction should energize.

For example, fi gure 60 shows a working input module which has sensed that the input is on. It then sends a signal to the processor, which sets the address to a value of 1 in the process image input table. The input instruction in the ladder logic diagram is then highlighted.

Figure 60. Working Input Module

01234567

01234567

DC POWERSUPPLY

+

-

PB1 INPUTDEVICE

I8.1 Q12.0

7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0

PROCESS IMAGE OUTPUT TABLEWORD 8

INPUT I8.1


70

If the module is not working, the input indicator might still be on, indicating that voltage is reaching the input terminal. The correct status of the input might not be sent by the input module to the processor. This means that the data bit remains 0 and the N.O. contact instruction remains false (not highlighted), as shown in fi gure 61.

Figure 61. Failed Input Module

Condition 2: Module Shorts Internally and Drags Power Supply to Ground

In the case of modules that fail by shorting internally and dragging the power supply to ground, the symptoms make it appear as if there is a power supply problem. By performing the tests learned earlier, the failed module should be iden-tifi ed and replaced.

All of the input module failures that have been described require the faulty module to be replaced.

01234567

01234567

DC POWERSUPPLY

+

-

PB1 INPUTDEVICE

I8.1 Q12.0

7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0


INPUT I8.1

INPUT INDICATORLIGHTS


71

SKILL 4 TEST A DISCRETE INPUT MODULE

Procedure Overview

In this procedure, you will test the operation of a discrete input module when it is operating properly and when it has failed.

1. Perform the following substeps to prepare a mechatronics station to test discrete input devices.




D. Verify that a PC adapter cable connects the PLC to the PC. 2. Perform the following safety check before you begin working on the station.

Make sure that you can answer yes to each item before proceeding.





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72

4. Perform the following substeps to create a project.

A. Start and log on to the PC.

B. Start the SIMATIC Manager

C. Create a new PLC project named L1S4_MS#_xxx where # is the Mecha-tronics station number (1-7) and xxx represents your initials.

D. Insert a SIMATIC 300 Station into the project.

E. Confi gure the hardware for the project.

F. Expand the project tree to display OB1.

G. Enter the ladder logic shown in fi gure 63 into the OB1 block of the project.

Figure 63. Single Cycle Single Cylinder Reciprocating Program

If you are programming the 87-MS5 Servo Robotic Assembly station, enter the program shown in fi gure 64.

Figure 64. Single Cycle Single Cylinder Reciprocating Program

H. Save OB1.

If any errors exist, correct them.

I0.1 I0.0I1.2 Q4.5

Q4.5

"STOP" "START""CYLINDER

RETRACTED""EXTENDCYLIR"

"EXTENDCYLIR"

I0.1 I0.0I1.2 Q4.5

Q4.5

"STOP" "START""CYLINDEREXTENDED"

"EXTENDCYLIR"

"EXTENDCYLIR"


73

5. Perform the following substeps to download the program and test its operation.

A. Remove all valve components from the station.

B. Download the program to the PLC.

C. Place the PLC into the RUN mode.

D. Display OB1 and press the Monitor button on the tool bar to go online.

E. Press and release the START pushbutton.

The cylinder should extend until it reaches its travel limit and stop.

F. Press and release the STOP pushbutton.

The cylinder should return to the retracted position.

This is the normal operation for the program.

If you are using 87-MS5, proceed to step 8. 6. Perform the following substeps to observe the proper operation of discrete

inputs in the PLC ladder routine.

A. Observe the input module indicator for I1.2.

Input Indicator _______________________________________(On/Off)


B. Measure the voltage for input I1.2 at the input module terminal.

Input Voltage _________________________________________ (Volts)


C. Observe the NO contact with the address I1.2 and record the contact status.

Contact Status ____________________________________ (True/False)

You should have recorded that the contact was true.

D. Press and Release the START pushbutton.

E. Observe the input module indicator for I1.2 and record your fi ndings in the space provided.


You should have observed the indicator turned off as the cylinder extended.

F. With the cylinder extended, measure the voltage for input I1.2 at the input module terminal. Record your measurement in the space provided.


You should have measured the 0 VDC with the cylinder extended.

G. With the cylinder extended, observe the N.O. contact for I1.2 and record your fi ndings in the space provided.


You should have observed the contact was false when the cylinder was extended.


74

H. Press and release the STOP pushbutton.

You have successfully observed the operation of a discrete input on the ladder logic of a PLC program.

7. Perform the following substeps to insert an open module fault into the input module.

A. Open the FaultPro software and log in using your login ID and password.





F. Select the appropriate workstation.

G. Place the cursor on the Enter Fault: fi eld and type 30.

H. Click the Enter button to the right of the fi eld to activate the fault.

I. Observe the input module indicator for I1.2 and record your fi ndings in the space provided.



J. Measure the voltage for input I1.2 at the input module terminal and record your measurement in the space provided.



K. Observe the N. O. contact for I1.2 and record your fi ndings in the space provided


You should have observed the contact was false.

L. Press and release the START pushbutton and observe the indicator for input I1.2. Record your fi ndings in the space provided.


You should have observed the cylinder would not extend.

This is the typical failure mode for a discrete input module. The signal is present at the input module terminal but does not appear in the ladder program.

From the observations and measurements, you can determine the input module has failed and must be replaced.


75

M. Click the Clear Fault button on the FaultPro dialog.

N. Observe the N.O. contact for I1.2 and record your fi ndings in the space provided.



You have successfully tested a mechatronics input module with and without faults.

O. Proceed to step 10. 8. Perform the following substeps to observe the proper operation of discrete

inputs in the PLC ladder routine (87-MS5 only).

A. Observe the input module indicator for I1.2.



B. Measure the voltage for input I1.2 the input module terminal.



C. Observe the N.C. contact with the address I1.2.

Record the contact status.



D. Press and Release the START pushbutton.

E. Observe the input module indicator for I1.2.

Record your fi ndings in the space provided.


You should have observed the indicator turned on when the cylinder extended.

F. Measure the voltage for input I1.2 at the input module terminal. Record your measurement in the space provided.


You should have measured 24 VDC with the cylinder extended.

G. Observe the N.C. contact for I1.2. Record your fi ndings in the space provided.


You should have observed the contact was false when the cylinder was extended.

H. Press and release the STOP pushbutton.

The cylinder should have retracted.

You have successfully observed the operation of a discrete input on the ladder logic of a PLC program.


76

9. Perform the following substeps to insert an open module fault into the input module.

A. Open FaultPro software and log in using your login ID and password.






G. Place the cursor on the Enter Fault: fi eld and type 30.

H. Click the Enter button to the right of the fi eld to activate the fault.

I. Observe the input module indicator for I1.2 and record your fi ndings in the space provided.



J. Measure the voltage for input I1.2 at the input module terminal and record your measurement in the space provided.

Input Voltage ____________ (Volts) You should have measured 0 VDC.

K. Observe the N.C. contact for I1.2 and record your fi ndings in the space provided


You should have observed the contact was true.

L. Press and release the START pushbutton and observe the indicator for input I1.2 an record your fi ndings in the space provided.


You should have observed the indicator turned on when the cylinder was extended.

M. Measure the voltage at the I1.2 terminal on the input module and record your measurement in the space provided.


You should have measured 24 VDC with the output actuated.

N. Observe the N.C. contact for I1.2. Record your fi ndings in the space provided.


You should have observed the contact was true.

This is the typical failure mode for a discrete input module. The signal is present at the input module terminal but does not appear in the ladder program.

From the observations and measurements, you can determine the input module has failed and must be replaced.


77

O. Click the Clear Fault button on the FaultPro dialog.

P. Observe the N.C. contact for I1.2 and record your fi ndings in the space provided.



You have successfully tested a mechatronics input module with and without faults.

10. Perform the following substeps to close FaultPro.

A. Click the Exit button to return to the Student Options window.

B. Click the Logout button to close the Student Options window.

C. Click the Exit button to close the FaultPro software. 11. Power down the mechatronics station and shut down the PC.


78


1. If the input ______ indicator turns on and off as the input device is operated, the input device is operating properly.

2. In a continuity test, the device is removed from the circuit completely and tested with the resistance or continuity settings of the ________.

3. To test an input device, operate the input device and observe the status of the input bit in the process image table or the ______ on the ladder diagram.

4. If the module is ________ the signal to the processor, the data bit should change from 0 to 1 in the PLC’s process image table and the ladder logic instruction should energize.

5. In the case of modules that fail by shorting internally and dragging the power supply to ground, the symptoms make it appear as if there is a(n) ____________ problem.


79

SEGMENT 4MECHATRONICS OUTPUT TROUBLESHOOTING

OBJECTIVE 9 DESCRIBE THE PLC FORCE FUNCTIONAND GIVE AN APPLICATION

Siemens’ PLCs provide a force function that enables users to override the status of the PLC’s I/O using the programming terminal, regardless of the status of the I/O and the program logic.

An input can be forced on to enable the input even if the input device wired to that terminal is off. It can also be forced off, which disables the input even if the input device is on. One application where inputs are forced is when program-mers need to test the operation of their program logic. Another is by maintenance personnel who need to cycle a machine to its startup position when a proximity switch or other input fails.

An output can also be forced either on or off. An output that is forced on remains on even if the program logic would turn the output off. An output that is forced off will not turn on while the program is running. Outputs are forced to turn an output device on or off, regardless of the state of the program or I/O devices. The most common application of output forcing is testing the operation of output devices.


80

A Force Values variable table (VAT) is used in a STEP 7 project to force I/O on and off. A Force Values VAT is shown in fi gure 65. A VAT can either be created temporarily to troubleshoot a problem, or can be saved in the Blocks folder as a permanent part of the project.

Figure 65. Force Values VAT

Forcing a PLC’s I/O can create dangerous situations, especially in a multi-user environment, which is supported by S7-300 PLCs. In a multi-user environment, several people can have access to the PLC project at the same time, usually over a network. The user should always determine the status of forces before creating or enabling any additional forces. This can be done by physically examining the processor, or by examining the online view of the LAD/STL/FBD Editor.

ADDRESSCOLUMN

DISPLAYFORMATCOLUMN

FORCEVALUE

COLUMN


81

OBJECTIVE 10 DESCRIBE HOW TO FORCE A PLC INPUT OR OUTPUT USING A VARIABLE TABLE

A variable table (VAT) can be used to force the state of a PLC’s I/O using the simple four-step procedure described in the following paragraphs:

Step 1: Go online with the PLC

Step 2: Open the Force Values Variable Table

Step 3: Create Forces

Step 4: Enable Forces

Step 1: Go Online with the PLC

The variable table is placed online if a connection can be established with a PLC when the table is opened. To monitor ladder logic when forces are applied, the LAD/STL/FBD Editor must be online with the PLC. The Monitor button on the Editor’s toolbar is used to go online with the PLC.

Step 2: Open the Force Values Variable Table

A new Force Values VAT can be opened using either the SIMATIC Manager or the LAD/STL/FBD Editor by selecting Display Force Values from the PLC menu, as shown in fi gure 66.

Figure 66. Selecting Display Force Values

PLCMENU

DISPLAY FORCEVALUES OPTION


82

An empty Force Values VAT should open in online view, as shown in fi gure 67.

Figure 67. Empty Force Values VAT

ADDRESSCOLUMN

DISPLAYFORMATCOLUMN

FORCEVALUE

COLUMN


83

Step 3: Create Forces

Forces are created by adding the address to the Address column of the empty Force Values VAT. After an address is entered, press Enter. The data type of the address should then be entered automatically into the Display Format column. Enter the force value, true or false, to the Force Value column. For example, if the address is a simple Boolean address like I0.0, enter a value of 1 or true to force the input on. An address that is set up to be forced true is shown in fi gure 68.

Figure 68. Force Values VAT

IDENTIFICATIONCOLUMN

ADDRESSCOLUMN DISPLAY FORMAT

COLUMN FORCE VALUECOLUMN


84

Step 4: Enable Forces

Forces are enabled by right-clicking in the Identifi cation column or the Force Value column, and selecting Force from the shortcut menu. The forces are acti-vated and a red F is placed in the Identifi cation column of the table to indicate that a force is active for that address, as shown in fi gure 69.

Figure 69. Force Values VAT with Forces Enabled

FORCE ENABLEINDICATOR

FORCE VALUECOLUMN

IDENTIFICATIONCOLUMN


85

If a force is currently active in a processor, the FRCE indicator should be illu-minated yellow, as shown in fi gure 70.

Figure 70. Processor with an Active Force

If a force, is active the LAD/STL/FBD Editor appears with FORCE displayed in yellow in the status area at the bottom of the screen. An address that is forced appears highlighted yellow with a red F next to it, as shown in fi gure 71.

Figure 71. LAD/STL/FBD Editor with an Active Force

PROCESSORFORCE

INDICATOR

CPU315-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIMATICS7-300

SIEMENS

FORCE STATUSINDICATOR

FORCEINDICATORS


86

SKILL 5 FORCE INPUTS AND OUTPUTS USING A VARIABLE TABLE

Procedure Overview

In this procedure, you will explore the operation of the PLC’s Force function by using a variable table (VAT) to force inputs and outputs on and off. This will familiarize you with the VAT, and with forcing inputs and outputs on the S7-300 system.

1. Perform the following substeps to prepare a mechatronics station.










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87




B. Open the program L1S4_M#_xxx you created in the previous skill.

If you are using a different mechatronics station than the one you used in the previous skill, you may have to modify the Cylinder Retracted address in the program to refl ect differences in I/O confi guration between the stations. The table in fi gure 73 shows the correct input address for the Cylinder Retracted switch.

STATION PROJECT

87-MS1 I1.2

87-MS2 I1.2

87-MS3 I1.2

87-MS4 I1.2

87-MS5 I1.3

87-MS6 I1.2

87-MS7 I1.2

Figure 73. Cylinder Retracted Addresses

C. Download the program to the PLC.

D. Place the PLC into the RUN mode.

E. Display OB1 and press the Monitor button on the tool bar to go online.

F. Press and release the START pushbutton.


G. Press and release the STOP pushbutton.


This is the normal operation for the program. 5. Perform the following substeps to open the variable table and create forces. Forces are entered, controlled, and deleted from a variable table. The table

may be saved with the program and re-used later.


88

A. Select Display Force Values from the PLC menu, as shown in fi gure 74.

Figure 74. Selecting Display Force Values from the PLC menu

PLCMENU

DISPLAY FORCEVALUES OPTION


89

An empty online Force Values VAT should open, as shown in fi gure 75. Notice that the Set Up Connection to the Confi gured CPU button is already selected.

Figure 75. Empty Online Force Values VAT

B. Select the Address column, shown in fi gure 75, of the table.

C. Enter I1.2 (I1.3 for 87-MS5) into the address column.

ADDRESSCOLUMN

DISPLAY FORMATCOLUMN

FORCE VALUECOLUMN

SET UPCONNECTION TO

CONFIGUREDCPU BUTTON


90

D. Press Enter.

The address should be entered into the address column and BOOL entered into the Display Format column, as shown in fi gure 76. The cursor should move to row 2’s address column.

Figure 76. Address Entered

E. Select row 1’s Force Value column by clicking it.

F. Enter 1 or true into the Force Value column.

ADDRESSCOLUMN


91

G. Press Enter.

The value of true should be entered into the Force Value column, as shown in fi gure 77.

You could have also entered a 1 into the Force Value column. If a 1 was entered, it would have changed to true when Enter was pressed.

Figure 77. Force Value Entered

H. Select row 2’s Address column by clicking it.

I. Enter Q4.5 into the address column.

FORCEVALUE

COLUMN


92

J. Press Enter.

The address should be entered into the address column and BOOL entered into the Display Format column. The cursor should move to row 3’s address column.

Do not enter a value into the Force Value column for row 2 yet. When the addresses are forced, all addresses in the table with a value in the Force Value column are forced. Leaving the Force Value column empty in row 2 allows only row 1 to be forced.

Figure 78. Address Entered


93

6. Perform the following substeps to force input I1.2 (I1.3 for 87-MS5) on.

A. Right-click in row 1’s Force Value column to display the shortcut menu shown in fi gure 79.

Figure 79. Shortcut Menu

B. Select Force from the shortcut menu.

The Force dialog shown in fi gure 80 should appear.

Figure 80. Force Dialog

SHORTCUTMENU


94

C. Click Yes on the dialog to force the input on.

A red F should appear in row 1’s identifi cation column, as shown in fi gure 81. This indicates that a force is active on the address. Notice that the FRCE indicator on the processor is illuminated yellow to indicate a force is active.

Notice the I/O modules. The module indicator for a forced input I1.2 (I1.3 for 87-MS5) does not turn on. The indicator turns on when voltage is applied to the input terminal.

Figure 81. Force Active

FORCEINDICATOR

FORCESTATUS

INDICATOR


95

D. Click LAD/STL/FBD from the task bar to display the ladder network.

E. Press and release the START pushbutton to extend the cylinder.

F. Observe the status of the NO contact for I1.2 (I1.3 for 87-MS5). Record your observation in the space provided.

NO Status _______________________________________ (True/False)

You should have recorded the contact was true.

The address should be highlighted and have a red F to the left of the address, as shown in fi gure 82. If the red F is not displayed, select “Display with” then “Address Identifi cation” from the View menu.

You should observe that address Q4.5 is not forced, although the address was entered in the VAC. Neither true nor false was entered in the Force Value fi eld for the address.

Figure 82. Network Forced Input Display

G. Observe the I1.2 (I1.3 for 87-MS5) indicator on the input module and record its status.


You should have recorded that the indicator was off. The indicator is controlled by voltage from the input device, not a force in the processor.

FORCEINDICATOR

I0.1"Stop"

I0.0"Start"

'F' "CylinderRetracted"

I1.2

Q4.5"Extend

Cylir"

Q4.5"Extend

Cylir"


96

7. Perform the following substeps to delete the force on address I1.2. Deleting a force means turning the force off on an S7-300 processor.

A. Click Var -- Force on the taskbar.

The VAT should be displayed.

B. Right-click in row 1’s column to display the shortcut menu again.

C. Select Delete Force from the shortcut menu.

The Delete Force dialog shown in fi gure 83 should appear.

Figure 83. Delete Force Dialog

D. Click Yes to remove the force.

The force should be disabled. The red F should disappear from row 1’s identifi cation column in the VAT and from the online display of OB1. However, the force is not removed from the table and can be forced again without having to re-enter the address and force value.


97

8. Perform the following substeps to force input I1.2 off.

A. Click the cursor in row 1’s Force Value column.

B. Change the text from true to false by typing false, or by entering 0.

C. Press Enter.

D. Right-click in row 1’s Force Value column to display a shortcut menu.

E. Select Force from the shortcut menu.

The Force dialog should appear.

F. Click Yes on the dialog to force the input off.

A red F should appear in row 1’s Identifi cation column to indicate that a force is active. The FRCE indicator should be illuminated amber on the processor to indicate a force is active.

G. Click LAD/STL/FBD from the task bar to display the ladder network.

Address I1.2 should be highlighted and a red F should be displayed to indicate the address has been forced.

You should notice the contact is not highlighted, indicating the instruction is false.

H. Press and release the STOP pushbutton to retract the cylinder.

I. Observe the status of the NO contact for I1.2 (I1.3 for 87-MS5). Record your observation in the space provided.

NO Status _______________________________________ (True/False)

You should have recorded the contact was false.

J. Observe the I1.2 (I1.3 for 87-MS5) indicator on the input module and record its status.


You should have recorded that the indicator was on. The input received a true signal but the address was forced off in the program.

K. Delete the force from I1.2.


98

9. Perform the following substeps to activate the force on address Q4.5 only. All addresses listed in the table that have a value listed in the Force Value

column will be forced when that option is selected. If it is not necessary to force all of the I/O listed in the table, there are two ways to prevent it from being forced. The fi rst is to remove the entry in the Force Value column for the address. The second way is to right-click on the row and select Row not Effective from the shortcut menu that appears.

A. Right-click the cursor in row 1’s Force Value fi eld to display a shortcut menu.

B. Select Row Not Effective from the shortcut menu.

Row 1 should now be displayed with a blue X in the Identifi cation column and next to the value in the Force Value fi eld, as shown in fi gure 84.

Figure 84. Row 1 Not Effective

C. Click in row 2’s Force Value column to select it.

D. Enter the text true or 1.

E. Press Enter to accept the entry.

F. Right-click in row 2’s Force Value fi eld to display the shortcut menu.

G. Select Force from the menu.


H. Click Yes on the dialog to force on output Q4.5.

Notice that a red F appears in row 2’s Identifi cation column to identify that it is being forced. The processor’s FRCE indicator should be yellow to indicate that forces are active. The cylinder controlled by output Q4.5 should actuate.

ROW NOTEFFECTIVEINDICATOR


99

I. Display the LAD/STL/FBD Editor by selecting it from the taskbar.

Notice that output coil Q4.5 is highlighted with a red F. It is the only address being forced by the processor.

10. Perform the following substeps to delete the force on output Q4.5.

A. Display the Force Value VAT by selecting it from the taskbar.

B. Right-click in row 2’s Force Value column to display the shortcut menu again.


The Delete Force dialog should appear.

D. Click Yes on the dialog to delete the force.

The force should be removed. The red F should disappear from row 2’s identifi cation column.

11. Perform the following substeps to force output Q4.5 off.

A. Display the Force Value VAT by selecting it from the taskbar.

B. Select row 2’s Force Value column by clicking in it.

C. Enter false or a 0 into the Force Value column.

D. Press Enter.

The value of false should be displayed in the Force Value column.

E. Right-click in row 2’s Force Value column to display a shortcut menu.

F. Select Force from the shortcut menu.


G. Click Yes on the dialog to force the input off.

A red F should appear in the identifi cation column. This indicates that the force is active. Also, notice that the FRCE indicator on the processor is illuminated yellow to indicate that a Force is active.

You should have also noticed the cylinder retracted when output Q4.5 was forced off.

H. Display the ladder program for OB1 and observe the network.

Record your observations in the space provided.

Observations _______________________________________________

You should notice the coil and NO contact are displayed with a red F to indicate the address has been forced.

You should also notice both instructions are false, indicating the address is forced off.

I. Press and hold the START pushbutton while observing the network. Record your observation in the space provided.

Observation ________________________________________________

You should have observed that the coil indicated the network was true, but the cylinder connected to output Q4.5 did not actuate. The force off over-rode the true rung condition.


100

J. Release the START pushbutton while observing the network. Record your observation in the space provided.

Observation ________________________________________________

You should have observed that the coil indicated the network was false and that the cylinder connected to output Q4.5 did not actuate.

12. Perform the following substeps to delete the force on output Q4.5.

A. Make sure the variable table is displayed on the monitor.

B. Right-click in row 2’s Force Value column to display the shortcut menu again.


The Delete Force dialog should appear.

D. Click Yes on the dialog to delete the force.

The force should be removed. The red F should disappear from row 2’s identifi cation column.

13. Repeat steps 4 through 12 until you are comfortable with the operation of the Force function.

14. Perform the following substeps to close the Force Values VAT.

A. Close the Force Values VAT by clicking the X in the top right- hand corner of the variable table window.

A dialog should appear asking if you wish to save the variable table.

B. Click No on the dialog to close the variable table without saving it.

You have successfully forced PLC inputs and outputs. 15. Power down the mechatronics station and shut down the PC.


101

OBJECTIVE 11 DESCRIBE HOW TO TEST A PLC DISCRETEOUTPUT DEVICE

If it is suspected that an output device is bad, perform the following three steps to test its operation:

Step 1: Force the PLC output

Step 2: Check the voltage at the PLC output terminal

Step 3: Test the output device and the wiring

Step 1: Force the PLC Output

The output device can be tested by forcing the PLC output that drives the suspected output device on and off using the variable table’s force value function. Use extreme caution when forcing the output as unexpected machine operation and/or movement may occur. If the output module indicator and the output device turn on and off as the module’s output is forced, the device is operating correctly. The problem may originate in the PLC program or in some area other than the output device itself.

If the output module indicators do not turn on and off as the output is forced, the problem may be in the output module itself. If the module’s indicators turn on and off, but the output device does not turn on and off as the output is forced, it does not verify that the output device is bad. The problem could be in the wiring between the output module and the output device, or the output module may not be supplying voltage to the device.

Step 2: Check the Voltage at the PLC Output Terminal

Next, measure the output module’s output terminal voltage. The output module’s output terminal voltage should change as the output is forced on and off if the output module is operating properly. Use the Force Values VAT function to turn the output on and off. Check the output terminals connected to the suspect device for a change in voltage.


102

The multimeter should read a high voltage when the output is on or off depending on the type of output module used and how it is connected. An active high DC output module or AC output module will cause the meter to read a high voltage when the output is turned on, as shown in fi gure 85.

Figure 85. Meter Reading of Active High AC or DC Output Module

COM

DC VOLTS

V

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

24 VDCPOWERSUPPLY

OUTPUTDEVICE

+

-

16-POINTOUTPUT MODULE


103

If the module is an active low DC type, the voltage should be low when the output is on, as shown in fi gure 86, and high when it is off.

Figure 86. Meter Reading of Active Low AC or DC Output Module

If the output module has relay contact outputs, the meter can read either high or low when the output is on, depending on how the output device is connected to the output module.

If the output voltage at the terminals does not change as the output is forced on and off, the problem is in the output module.

Step 3: Test the Output Device and the Wiring

If the output voltage at the terminals does change, and the output device does turn on and off, either the output device is bad, or there is a problem in the inter-face wiring between the output module and the device. The wiring can be checked by using a multimeter to measure continuity between the output terminal and the output device. If the output module is good, and there is continuity between the output terminal and the output device, replace the output device.

01234567

1

10

2

3

4

5

6

7

8

9

11

20

12

13

14

15

16

17

18

19

01234567

l

1000V750V

OFF

DM15XLAVETEK

750 20020

2

200m

200

2m

20m

200m

10AA

10A200m

20m2m2002002k

20k200k

2000k20M

2000M

LOGIC

200m2

20200

1000 VV

A

200mA 10A

MAX

COMV

FUSED

FUSED

W

DC VOLTS

24 VDCPOWERSUPPLY

OUTPUTDEVICE

+

-

16-POINTOUTPUT MODULE


104

SKILL 6 TEST A DISCRETE OUTPUT DEVICE

Procedure Overview

In this procedure, you will insert faults in the mechatronics station outputs then force the outputs to test the output devices. This will familiarize you with troubleshooting output devices.











Tie up long hair







105




B. Open the program L1S4_M#_xxx you created in an earlier skill.


STATION PROJECT

87-MS1 I1.2

87-MS2 I1.2

87-MS3 I1.2

87-MS4 I1.2

87-MS5 I1.3

87-MS6 I1.2

87-MS7 I1.2











106

5. Perform the following substeps to insert an open fault into the device connected to output Q4.5.

A. Open FaultPro software and log in using your login ID and password.






G. Verify that the FaultPro template matches the mechatronics station using the table in fi gure 89.

STATION FAULTPRO TEMPLATES

87-MS1 1 - Feeding

87-MS2 2 - Gauging

87-MS3 3 - Indexing

87-MS4 4 - Sorting

87-MS5 5 - Assembly

87-MS6 6 - Torquing

87-MS7 7 - Storage

Figure 89. Project Names and FaultPro Templates

H. Place the cursor on the Enter Fault: fi eld and type 23 to enter a fault for output Q4.5.

I. Click the Enter button to the right of the fi eld to activate the fault.

J. Press and release the START pushbutton to activate the output. Observe the cylinder controlled by output Q4.5. Record your observation in the space provided.

Cylinder _________________________________(Retracted/Extended)

You should have observed that the cylinder remained in its retracted position.

K. Observe the coil for output Q4.5. Record your observation in the space provided.

Observation ______________________________________ (True/False)

You should have observed the coil was true and the seal-in contact was true.

L. Observe the output module indicator for Q4.5. Record your observation in the space provided.

Observation _________________________________________(On/Off)

You should have observed the output was on.


107

M. Measure the voltage on the output module terminals for Q4.5. Record your measurement in the space provided.



From your observations and measurement, you should conclude that the PLC and output module are operating correctly. The failure could be caused by one of the following:

No air to the solenoid valve

Failed cylinder

Failed solenoid valve

Failed wiring in the solenoid valve circuit

N. Manually operate the solenoid valve to verify the presence of air and the integrity of the cylinder. Record your results in the space provided.

If the cylinder extends when the valve is manually operated, the problem is isolated to the valve coil and wiring.

The table in fi gure 90 shows the valve labels associated with fault 23.

STATION SOLENOID

87-MS1 Feed Part Extend

87-MS2 Part Reject Extend

87-MS3 Transfer Cylinder

87-MS4 Sorting Cylinder

87-MS5 Spool Insertion

87-MS6 Extend Clamp

87-MS7 Pickup Extend

Figure 90. Output Devices Affected by Fault 23

Manual operation __________________________(Retracted/Extended)

You should have observed the cylinder extended when the solenoid valve was manually operated.

This shows the failure is in either the valve or the wiring to the valve.

Fault 23 simulates a failure in the solenoid valve.

O. Click the Clear Fault button to clear the fault.

You should have observed that the cylinder extended.

P. Press and release the STOP pushbutton.


108

6. Perform the following substeps to insert an open fault into the device attached to output Q4.6.

If you are using the 87-MS6 station, proceed to step 7.

A. Place the cursor on the Enter Fault: fi eld and type 24.

B. Click Enter to enable the fault.

C. Force on output Q4.6.

D. Observe the cylinder controlled by output Q4.6. Record your observation in the space provided.

The table in fi gure 91 shows the valve labels associated with fault 24.

STATION SOLENOID

87-MS1 Pickup Cylinder Extend

87-MS2 Part Eject Extend

87-MS3 Lift Cylinder Extend

87-MS4 Acrylic Queue Engaged

87-MS5 Clamp 1 Extend

87-MS6 N/A

87-MS7 Grip


Cylinder _________________________________(Retracted/Extended)

You should have observed that the cylinder remained in its retracted position.

E. Observe the output module indicator for Q4.6. Record your observation in the space provided.

Observation _________________________________________(On/Off)

You should have observed the output was on.

F. Measure the voltage on the output module terminals for Q4.6. Record your measurement in the space provided.



From your observations and measurement, you should conclude that the PLC and output module are operating correctly. The failure could be caused by one of the following:

No air to the solenoid valve

Failed cylinder

Failed solenoid valve

Failed wiring from the output module to the solenoid valve


109

G. Manually operate the solenoid valve to verify the presence of air and the integrity of the cylinder. Record your results in the space provided.

Manual operation __________________________(Retracted/Extended)

You should have observed the cylinder extended when the solenoid valve was manually operated.

Fault 24 simulates faulty wiring between the output module and the solenoid.

You have successfully forced outputs to test a mechatronics output device.

H. Remove the force from output Q4.6 and close the force table.

I. Close OB1 and the SIMATIC Manager.

J. Click the Clear Fault button to clear the fault.

K. Close the FaultPro software.

L. Use the CYCLE SELECT switch to reset the mechatronics station. 7. Power down the mechatronics station and shut down the PC.


110

OBJECTIVE 12 DESCRIBE HOW TO TEST A DISCRETE OUTPUT MODULE

If an output module is suspected bad, perform the following substeps to test the module:

Step 1: Check the status indicators on the processor module

Step 2: Check the output module’s status indicators

Step 3: Measure the output module’s supply voltage

Step 4: Force the output

Step 5: Measure the output terminal’s voltage

Step 1: Check the Status Indicators on the Processor Module

Check the processor’s status indicators to verify that the processor is in either RUN or RUN-P mode. Remember, the PLC’s input and output indicators may turn on and off even in STOP mode. Verify that the processor’s FRCE indicator is off. A forced input or output could appear as a fault. Check the SF and BF indicators and verify that they are not red to make sure a fault is not caused by the program or network failures. Output modules may occasionally fail internally, causing the processor to fault. Troubleshooting processor faults will be covered later.

Figure 92. Processor Indicators

SYSTEM FAULT

BUS FAULT

5VDC FAULT

FORCE

RUN

STOP

CPU315-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIMATICS7-300

SIEMENS


111

Step 2: Check the Output Module’s Status Indicators

When operating normally, the output status indicators on the output module should be either on (green) or off, as shown in fi gure 93.

Figure 93. Output Indicators

Check the output module’s status indicators to verify the operation of the module and its outputs. If the module appears to be operating correctly, continue to step 3. If it is not operating correctly, replace the output module.

Some output modules contain an SF diagnostic indicator that illuminates red if a fault is detected, such as a blown fuse. If the module has a red SF diagnostic indi-cator, the Module Information dialog can be used to check the status of the module. The dialog is accessed by selecting Diagnostic/Setting, then Module Information from the SIMATIC Manager’s PLC menu. Output modules without an SF indicator must be tested manually.

01234567

DI+2

IN

01234567

DO+0

OUT

01234567

DI+0

IN

01234567

DI+1 DO+0

01234567

CPU314C-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIEMENS

X1 MPI X2 DP

V2.0.11

OUTPUTSTATUS

INDICATORS

OUTPUTSTATUS

INDICATORS


112

Step 3: Measure the Output Module’s Supply Voltage

Measure the voltage of the output module’s supply terminals. If no or low voltage is measured, the problem is in control power to the output module. Trou-bleshoot the supply wiring to the module. If control power is measured at the output module’s supply terminals, continue to step 4.

Step 4: Force the Output

If the output module is still suspected as bad, use the Force Values VAT func-tion to force on an output, as shown in fi gure 94. If a particular output terminal is suspected, force that output on. The forced output’s status indicator should corre-spond to the forced condition. It should illuminate green when forced on, and off when forced off. If the output indicator does not turn on and off with the applied force, the module is bad and should be replaced. If the indicator does turn on and off with the applied force, another check is required. Continue to step 5.

Figure 94. Output Module Forced On

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

I8.1 Q12.0

7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0

L1

LAMPL1ON

OUTPUT TERMINALQ12.0


OUTPUT ISFORCED ON

F


113

Step 5: Measure the Output Terminal’s Voltage

Force the suspected output on and off using the Force Values VAT function. Measure the output terminal voltage, as shown in fi gure 95. The output terminal voltage should be high when the output is forced on, and low when the output is forced off if the output module is an active high or sourcing module. If there is no change in terminal voltage as the output is forced on and off, the output module may be bad.

Figure 95. Measurement of Output Voltage

01234567

DI+2

IN

01234567

DO+0

OUT

01234567

DI+0

IN

01234567

DI+1 DO+0

01234567

CPU314C-2DPSF

BF

DC5V

FRCE

RUN

STOPPUSH

RUNSTOPMRES

SIEMENS

X1 MPI X2 DP

V2.0.11

COM

24 VDC

V

4M2L

2M

3L

3M1M

+

+

1L+


114

SKILL 7 TEST A DISCRETE OUTPUT MODULE

Procedure Overview

In this procedure, you will use the PLC’s status indicators, the force function, and a multimeter to test the operation of an output module.











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115



B. Open the program L1S4_M#_xxx you created in an earlier skill.


STATION INPUT

87-MS1 I1.2

87-MS2 I1.2

87-MS3 I1.2

87-MS4 I1.2

87-MS5 I1.3

87-MS6 I1.2

87-MS7 I1.2











116

5. Perform the following substeps to insert a module shorted fault into output Q4.5.

A. Log in to the FaultPro software and enter fault 32 in the Single Fault Mode. Observe the status of the output device associated with output Q4.5 and record your fi ndings in the space provided.

Use the table in fi gure 99 to identify the output device controlled by output Q4.5.

STATION INPUT

87-MS1 Feed Part Extended

87-MS2 Part Reject Extended

87-MS3 Transfer Cylinder

87-MS4 Sorting Cylinder

87-MS5 Spool Insertion

87-MS6 Extend Clamp

87-MS7 Pickup Extend


Output Device Status: ___________________ (Activated/De-Activated)

You should have observed the output was activated.

B. Observe the indicator for output Q4.5 on the output module and record its status in the space provided.

Output Q4.5 Indicator _________________________________(On/Off)


C. Measure the voltage at the Q4.5 output module terminal and record your measurement in the space provided.

Q4.5 Output Voltage: __________________________________ (Volts)


D. Observe the network coil at address Q4.5 and record the network’s status.

Q4.5 Network Status _______________________________ (True/False)

You should have recorded that the network was false.

The PLC is commanding the output to be off but the output device is actu-ated. The output module point is shorted. This is the typical failure mode for a PLC output point and is resolved by replacing the output module.


117

E. Force off output Q4.5 and record the status of the output device in the space provided.

Output Device Status _______________________(Retracted/Extended)

You should have recorded the device was extended.

Because the failure is in the power section of the output module, forcing the output off has no effect.

F. Press the Emergency Stop button and record the status of the output device in the space provided.

Output Device Status ___________________ (Activated/De-Activated)

You should have recorded the device was de-activated.

The Emergency Stop controls the MCR circuit, which controls the power to the output modules. Pressing the Emergency Stop button de-activates the MCR, which removes power from the output module and de-activates all outputs. The hardwired circuit is used to turn off outputs without shut-ting down the whole system.

G. Remove the force from output Q4.5.

H. Pull the Emergency Stop button and press the Output Power button to restore power to the output modules.

You have successfully tested a PLC discrete output module.

I. Press the Clear Fault button to remove the fault and close the FaultPro software.

The cylinder should have actuated. 6. Power down the mechatronics station and shut down the PC.


118


1. Siemens’ PLCs provide a force function that enables users to ______ the status of the PLC’s I/O using the programming terminal, regardless of the status of the I/O and the program logic.

2. If a force is currently active in a processor, the ________ indicator should be illuminated yellow.

3. Use extreme caution when forcing the output as _________ machine operation and/or movement may occur.

4. Remember, the PLC’s input and output indicators may turn on and off even in ________ mode.

5. If the output module is still suspected as bad, use the ____________________ VAT function to force on an output.

Documents

MECHATRONICS TROUBLESHOOTING LEARNING · PDF file · 2017-01-03covers the types of failures that occur and how to diagnose those problems. ... SKILL 2 Troubleshoot a mechatronics