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SDI-12 ENCODER Without logger
Stand Alone Part # 93821-02
9/29/2017
Operations Manual
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1 Table of Contents
SAFETY AND EQUIPMENT PROTECTION ………………………… 3 1 INTRODUCTION ........................................................................... 5
General Description ……….................................................... 5 Safety Information ………. ...................................................... 5 Float Wells and Instrument Shelters ……………….................. 5 Type A/F Encoder Specifications………….. ............................ 5
2 INSTALLATION ............................................................................ 6 Type A/F Encoder on Type A Recorder................................. 6 Electrical Installation ............................................................. 7
3. SDI-12 COMMAND LIST…………………………………………… 8
4. MAINTENANCE AND TROUBLESHOOTING ............................ 9 Maintenance........................................................................... 9 Troubleshooting Chart………….............................................. 9 Factory Assistance ................................................................. 9
LIST OF ILLUSTRATIONS Figure 2. Installation on the Type A Recorder ............................. 6
ADDENDUM 1 - SDI-12 PROTOCOL ………………………………. 11
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Safety and Equipment Protection Information Before performing any procedures in this manual, please read all applicable WARNINGS and CAUTIONS in this section. Power sources, including batteries, can be a particular hazard to the user. The SDI-12 ENCODER instruction manual and EncoderSet GUI interface is organized so that the experienced user can operate the instrument with the least amount of reading. WARNING! ELECTRICAL POWER CAN RESULT IN DEATH, PERSONAL INJURY OR CAN CAUSE DAMAGE TO EQUIPMENT. If the instrument is driven by an external power source, disconnect the instrument from that power source before attempting any repairs. WARNING! BATTERIES ARE DANGEROUS. IF HANDLED IMPROPERLY, THEY CAN RESULT IN DEATH, PERSONAL INJURY OR CAN CAUSE DAMAGE TO EQUIPMENT. Batteries can be hazardous when misused, mishandled, or disposed of improperly. Batteries contain potential energy, even when partially discharged. WARNING! ELECTRICAL SHOCK CAN RESULT IN DEATH OR PERSONAL INJURY. Use extreme caution when handling cables, connectors, or terminals; they may yield hazardous currents if inadvertently brought into contact with conductive materials, including water and the human body. CAUTION! Be aware of protective measures against environmentally caused electric current surges. In addition to the previous warnings and cautions, the following safety activities should be carefully observed. Children, Adolescents NEVER give batteries to young people who may not be aware of the hazards associated with batteries and their improper use or disposal. Jewelry, Watches, Metal Tags To avoid severe burns, NEVER wear rings, necklaces, metal watch bands, bracelets, or metal identification tags near exposed battery terminals. Heat, Fire NEVER dispose of batteries in fire or locate them in excessively heated spaces. Observe the temperature limit listed in the instrument specifications. Charging NEVER charge “dry” cells or lithium batteries that are not designed to be charged.
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NEVER charge rechargeable batteries at currents higher than recommended ratings. NEVER recharge a frozen battery. Thaw it completely at room temperature before connecting charger. Unvented Container NEVER store or charge batteries in a gas-tight container. Doing so may lead to pressure buildup and explosive concentrations of hydrogen. Short circuits NEVER short circuit batteries. High current flow may cause internal battery heating and/or explosion. Damaged Batteries Personal injury may result from contact with hazardous materials from a damaged or open battery. NEVER attempt to open a battery enclosure. Wear appropriate protective clothing and handle damaged batteries carefully. Disposal ALWAYS dispose of batteries in a responsible manner. Observe all applicable federal, state, and local regulations for disposal of the specific type of battery involved. NOTICE Stevens makes no claims as to the immunity of its equipment against lightning strikes, either direct or nearby. The following statement is required by the Federal Communications Commission: WARNING - This equipment generates, uses, and can radiate radio frequency energy with the optional Wi-Fi module and, if not installed in accordance with the instructions manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protection against such interference when operated in a commercial environment. USER INFORMATION Stevens makes no warranty as to the information furnished in these instructions and the reader assumes all risk in the use thereof. No liability is assumed for damages resulting from the use of these instructions. We reserve the right to make changes to products and/or publications without prior notice.
Introduction GENERAL DESCRIPTION
The Stevens® Type SDI-12 A/F Encoder is an input device sensor for the primary purpose of encoding water level or shaft
position. The basic encoding device is a digital encoder, which transforms potentiometer’s output signals to SDI-12 digital output. Connections are easily made to the screw-clamped type of barrier strips on the Encoders, using only a flat-bladed screwdriver. Other receiving instruments may be used that are SDI-12 input compatible.
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SAFETY INFORMATION
Grounding and Protection from Lightning
Every remote environmental monitoring station should include a plan for an Earth Ground. For more information on this important topic when setting up your SDI-12 ENCODER, please see Ground and Protection section for additional reference information. http://www.stevenswater.com/articles/lightning_protection.aspx Before performing any procedure in this manual, read all applicable warnings and cautions. FLOAT WELLS AND INSTRUMENT SHELTERS Information on suitable float wells and instrument shelters can be found in the Stevens Water Resources Data Book, any edition. TYPE SDI-12 A/F ENCODER SPECIFICATIONS Type SDI-12 A/F Encoder, basic: Precision Potentiometric signal converted to Digital SDI-12 output, in sealed enclosure; encoder input shaft is threaded onto recorder input shaft; float pulley load is not transferred to encoder. Output: Digital SDI-12 Power: +10 to 16VDC, 5 mA typical. Cable: Power and signal output connections are made to a 3 conductor, shielded 3 foot cable; conductor size #22 AWG stranded wire. Shaft Speed: 1 Rev. per second
Technical Specification SDI-12 ENCODER
Power Requirements
9.6 - 16 Vdc, 4 mA standby current
Temperature and Humidity
Operating: -40 to 158 F (-40 to 70 C)
NEMA 4 enclosure: 100% condensing
Fiberglass enclosure: 95% non-condensing
Serial:
Input type: SDI-12
Sensor power: 12 VDC continuous.
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Physical Size (L x H x D) for outside dimensions of NEMA-4 enclosure with lid.
8.25 inch (includes the base) x 7.50 inch x 8.75 inch (includes shaft extension)
(20.96 cm x 19.05 cm x 22.23 cm)
Installation MECHANICAL INSTALLATION
Unpack and examine the SDI-12 ENCODER carefully. If there is any apparent shipping damage, contact the shipper immediately. Also contact the factory for replacement of the unit.
Position the SDI-12 ENCODER so it can be connected to a suitbable power source. Make sure that the external enclosure you have selected provides enough side room to accommodate any external cable connections.
The SDI-12 ENCODER is supplied with an aluminum bracket with pre-drilled holes for mounting purposes. Mounting hole diameter are .3 inch (0.762 cm)
To install float pulley, unscrew locking disk and cupped washer. Place pulley onto the shaft all the way to back and re-install cupped washer with open towards the pulley. Screw back on the locking disk (hand tight) then carefully lock in place by tightening evenly the left hand and right hand screws. Do not overtighten.
Looking at the input shaft as in the photo on the right, Clockwise is up. When installing the float gear, the float will be on the left side of the pulley. To reverse direction, install the float on the opposite side, OR enter the pulley size as a negative number (-1.500 for instance).
7.37 in. ( 19.05 cm)
4.0 in.
(10.19 cm)
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Electrical Installation
Connecting Power
Connect the 12Vdc power cable to the SDI-12 ENCODER. Barrier strip located on the side of the SDI-12 ENCODER provides the connections to Power and Ground. Plus (+) sign for Power and a negative Sign (-) for ground. Input power requirements: 12 VDC. SDI-12 data will be on the 3rd screw terminal.
Front Panel Operation Front panel consist of a display with an “UP” button, a “DOWN” button and LCD “ON” button
Pressing the “UP” button will increment the reading. Keeping the button depressed it will increment at an increasing rate.
Pressing the “DOWN” button will decrement the reading. Keeping the button depressed will decrement the reading at an
increasing rate.
UP BUTTON
DOWN BUTTON
“LCD “ON” BUTTON BUTTON
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LCD Display Backup battery installation
The LCD display is supplied with a 9 VDC battery that is not installed. To install disconnect any external power and
remove the 4 mounting screws that hold the front panel in place. Open slowly so as to not disturb any of the internal
wiring connections.
Insert the battery and re-install the front panel taking care to make sure that no cables are pinched in the process.
To test, disengage any external power and then press the LCD “ON” button. The display should turn on showing zeros. If
not, then check the 9 Volt Battery connection again to make sure it properly installed.
SDI-12 Serial Commands
aXEI! Initialize the encoder to zero.
aXEC1.500! Set the pulley circumference factor
aXEC! Load the Pulley Circumference into buffer
aXEP! Read the Pulley Circumference from buffer
aXEL30! Set LCD timeout after button push
aI! Get ID
aM! Take a reading
aD0! Retrieve reading
aAb! Change sensor address
?! Retrieve address of a single SDI-12 sensor
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2 ADDENDUM 1
3 SDI-12 PROTOCOL (reference only)
What is SDI-12?
SDI-12 stands for serial data interface at 1200 baud. It is a standard to interface battery powered data
recorders with micro-processor based sensors designed for environmental data acquisition (EDA).
EDA is accomplished by means of a sensor, or sensors, and a data recorder which collects and saves the data. SDI-12 is a standard communications protocol which provides a means to transfer measurements
taken by an intelligent sensor to a data recorder. An intelligent sensor typically takes a measurement, makes
computations based on the raw sensor reading, and outputs the measured data in engineering units. For
example, an SDI-12 pressure sensor may take a series of pressure measurements, average them, and then
output pressure in psi, inches of mercury, bars, millibars, or torrs. The sensor's micro-processor makes the
computations, converts sensor readings into the appropriate units, and uses the SDI-12 protocol to transfer data to the recorder.
What requirements make SDI-12 particularly useful?
SDI-12 is used in applications with the following requirements:
• battery powered operation with minimal current drain
• use of one data recorder with multiple sensors on a single cable
• use with microprocessor-based sensors that perform complex calibration algorithms or make internal computations
• Up to 200 feet of cable between a sensor and a data logger.
These requirements are necessary to acquire hydrologic data at remote sites. Most sites use battery
powered data recorders to operate for long and unattended periods of time.
Why use micro-processor based sensors anyway?
A micro-processor in the sensor may calibrate the sensor, control sensor measurements, and convert raw sensor readings into engineering units. The micro-processor also controls the SDI-
12 interface. It accepts and decodes instructions received from the data recorder, starts the
measurements, controls all timing, and uses the SDI-12 protocol to communicate with the data recorder.
Can more than one parameter be measured with a single data recorder?
Yes. SDI-12 is a multi-drop interface that can communicate with multi-parameter sensors. Multi-drop means that more than one SDI-12 sensor can be connected to a data recorder. The SDI-12 bus is capable of
having ten sensors connected to it. Having more than ten sensors, however, is possible. Some SDI-12 users
connect more than ten sensors to a single data recorder.
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Multi-parameter means that a single sensor may return more than one measurement. For example, some water quality sensors return temperature, conductivity, dissolved oxygen, pH, turbidity, and depth.
Advantages of SDI-12
A serial-digital interface is a logical choice for interfacing microprocessor-based sensors with a
data recorder. This has advantages for sensors and data recorders.
• Unique and complex self calibration algorithms can be done in microprocessor-based sensors.
• Sensors can be interchanged without reprogramming the data recorder with calibration or
other information.
• Power is supplied to sensors through the interface.
• Hybrid circuit and surface mount technologies make it practical to include the power supply regulator, a microprocessor, and other needed circuitry in small sensor packages.
• Sensors can use low cost EEPROMs (electrically erasable programmable read only memory)
for calibration coefficients and other information instead of internal trimming operations.
• The use of a standard serial interface eliminates significant complexity in the design of data
recorders.
• Data recorders can be designed and produced independently of future sensor
development.
• SDI-12 data recorders interface with a variety of sensors.
• SDI-12 sensors interface with a variety of data recorders.
• Personnel trained in SDI-12 will have skills to work with a variety of SDI-12 data recorders and SDI-12 sensors.
In what applications are SDI-12 devices used?
SDI-12 is used in water resource research and management, industry, government, and agriculture. For example, the U.S. Geological Survey uses over 4000 SDI-12 sensors in its data
collection networks. SDI-12 sensors are available that measure the following:
• conductivity
• dissolved oxygen
• distance
• groundwater level
• petroleum hydrocarbons in water
• pH
• pressure
• redox (ORP)
• tank level
• temperature
• tide and sea state
• turbidity
• water velocity
• weight of snow and ice on a snow pillow
More information on the SDI-12 protocol can be found at
http://www.sdi-12.org/
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Extended SDI-12 Commands
For a full description of extended commands, refer to the SDI-12 SENSOR user manual
a – Sensor Address
The first character of every command is a sensor address. Likewise, the first character of every response is also the address character. This command spec uses the character “a” to denote the
address character.
The default SDI-12 SENSOR address is ASCII ‘0’. The standard SDI-12 address range is ASCII ‘0’ through ASCII ‘9’. The SDI-12 SENSOR supports addresses between ASCII ‘0’ and ASCII ‘~’
(Decimal 48 – Decimal 126).
b – New Sensor Address
The new sensor address character is used as a parameter in the Change Address command, as
well as in response to the Change Address command. It has the same requirements as the Sensor Address (detailed above).
? – Wildcard Address
The wildcard address character, ASCII ‘?’, is supported for any SDI-12 command. It may be used in place of the sensor address character, and in that case, any attached probe will
respond, regardless of the probe’s address.
ttt – Seconds Until Ready
The number of seconds until the requested measurements will be ready. By default, the SDI-
12 SENSOR takes 1 second to prepare readings.
n, nn – Number of Readings
The number of measurement values the sensor will return via one or more D commands.
Standard measurement commands may return 0-9 readings, while concurrent measurement commands may return 0-99 readings.
ll – SDI-12 Version
Two characters specify the SDI-12 version number. The SDI-12 SENSOR supports SDI-12 version 1.2, so the shipping version number is “12”.
mmmmmm – Sensor Model
Six characters specify the sensor model number. The SDI-12 SENSOR shipping model number is 000001.
vvv – Sensor Version
Three characters specify the sensor version. The SDI-12 SENSOR shipping version is 2.0.
######## – Serial Number
Eight characters specify the sensor serial number. The SDI-12 SENSOR serial number is set at the factory.
Basic SDI-12 Command Grammar
Transparent
Mode SDI-12 sensors are normally shipped with the sensor address set to 0
(zero).
To have multiple sensors on one logger, each sensor must have a unique
address.
To change the Address of a SDI-12 SENSOR, enter the Transparent Mode on the LOGGER
Commands sent with the LOGGER in Transparent Mode go directly to the SDI-12
SENSOR and do not affect the LOGGER
settings.
Basic SDI-12 Commands
Acknowledge Active
Used to ensure that a sensor is responding to a data recorder or another SDI-12 device. It asks a sensor to acknowledge its presence on the SDI-12 bus. Command: a! Response: a<CR><LF>
Change Sensor Address
Used to change the address of a SDI-12 sensor. Command: aAb!
Response: b<CR><LF>
Send Identification
Used to retrieve the ID string of a SDI-12 sensor that supports software changeable addresses,
as the SDI-12 SENSOR
does. Command: aI! Response: allcccccccccmmmmmmvvxxx…xx<CR><LF>
Address Query
Used to retrieve the address of a single SDI-12 sensor Command: ?!
Response: a<CR><LF>
Maintenance and Trouble Shooting
MAINTENANCE
a. Battery Charger. This provides the additional benefit of continued operation on the battery supply, when there is intermittent power loss to the charger.
b. Observe good instrumentation grounding, shielding, and power sourcing practices to maintain maximum battery life and prolong the operating life of connected instruments.
.
TROUBLE SHOOTING If you cannot solve the problem in the field, call and ask for a Stevens Customer Technical Representative. The toll-free number for Stevens is 1-800-452-5272, and the call is free from Canada or the U.S.A. For calls outside of the U.S.A. or Canada, please dial 1-503-445-8000. Customer support can also be reached via email at [email protected]. Please provide an instrument description and serial number, when possible. Many questions can be answered by telephone, or you may obtain an authorization for return of the equipment, should that be necessary. The factory is open Monday through Friday from 7 a.m. to 5 p.m., Pacific Time. If no one is available, leave a message at any time on the phone mail system; just clearly tell us your name, location, telephone number and how to reach you.
