Application for Communication - Siemens · PDF fileWinAC Basis and S7-200 Stations via S7 Communication ... S7-300 / S7-400 164 bytes / 400 ... BSEND / BRECEIVE Bilaterally configured

Application for Communication

Client-Server Communications between WinAC Basis and S7-200 Stations via S7 Communication (PUT/GET)

Client-Server Communications between WinAC Basis and S7-200 Stations via S7 Communication

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Warranty, Liability and Support

We do not accept any liability for the information contained in this document. Any claims against us - based on whatever legal reason - resulting from the use of the examples, information, programs, engineering and performance data etc., described in this document shall be excluded. Such an exclusion shall not apply in the case of mandatory liability, e.g. under the German Product Liability Act (“Produkthaftungsgesetz”), in case of intent, gross negligence, or injury of life, body or health, guarantee for the quality of a product, fraudulent concealment of a deficiency or breach of a condition which goes to the root of the contract (“wesentliche Vertragspflichten”). However, claims arising from a breach of a condition which goes to the root of the contract shall be limited to the foreseeable damage which is intrinsic to the contract, unless caused by intent or gross negligence or based on mandatory liability for injury of life, body or health. The above provisions does not imply a change in the burden of proof to your detriment. The Application Examples are not binding and do not claim to be complete regarding the circuits shown, equipping and any eventuality. They do not represent customer-specific solutions. They are only intended to provide support for typical applications. You are responsible in ensuring that the described products are correctly used. These Application Examples do not relieve you of the responsibility in safely and professionally using, installing, operating and servicing equipment. When using these Application Examples, you recognize that Siemens cannot be made liable for any damage/claims beyond the liability clause described above. We reserve the right to make changes to these Application Examples at any time without prior notice. If there are any deviations between the recommendations provided in these Application Examples and other Siemens publications - e.g. Catalogs - then the contents of the other documents have priority.

Copyright© 2004 Siemens A&D. It is not permissible to transfer or copy these Application Examples or excerpts of them without first having prior authorization from Siemens A&D in writing.

For questions about this document please use the following e-mail-address: [email protected]

mailto:[email protected]


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Table of Contents

1 Task ............................................................................................................. 4 2 Setup of the Automation Solution ............................................................ 5 2.1 Required components .................................................................................. 5 3 Function Mechanisms and Program Structures ..................................... 7 3.1 Core properties of the S7 protocol and its services ..................................... 7 3.2 Configuration of an S7 connection ............................................................... 8 3.3 User interface PUT / GET .......................................................................... 10 3.4 Principle structure of this example ............................................................. 12 3.5 Program structures..................................................................................... 13 3.6 Program flow in the client station ............................................................... 15 3.7 Server interface.......................................................................................... 18 4 Installation of Hardware and Software................................................... 19 4.1 Hardware configuration .............................................................................. 19 4.2 Installation of the software ......................................................................... 19 4.3 Core configurations of the application........................................................ 22 4.4 Operator control and monitoring ................................................................ 24


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1 Task

Technological task / overview

Fig. 1-1

Via the MPI bus, a WinAC base station is connected to several S7-200 substations to which it sends data records upon their request.

Requirements on the application The WinAC station is to provide small to medium-sized data records (parameter records) which e.g. variably control the response of the substations. If one of the substations requests a specific data record, the master station (WinAC) is to send this data record to the substation. In order to do this, an active polling mechanism is to access a passive bit interface of the substation on the master station side to determine whether a request has been made. The communication is to be effected using the S7 communications service PUT / GET via MPI.


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2 Setup of the Automation Solution

Display of the components involved The overview picture below shows the hardware setup of the sample application with the standard and user software components.

Fig. 2-1

2.1 Required components

Hardware components The following hardware components are required to use the application:

Table 2-1

Component MLFB / Order number Note

Power PG 6ES7750-2CA52-4FB4 S7-CPU 222 212-1BB22-0XB0 Or similar CPU, e.g.

221 On Board CP 5611 Part of the PG

hardware MPI cable 6ES7 901-0BF00-0AA0


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Software components The following software components are required to use the application:

Table 2-2

Component MLFB / Order number Note

Standard software STEP7 V5.2 SP1 6ES7810-4CC06-0YX0 STEP7 Micro/Win 32 V3.2

6ES7810-2BC02-0YX0 V 3.2.3.17 was used for this application

SIMATIC NET V6.1 SP1

6GK1704-0AA06-3AA0

WinAC Basis V4.0 6ES7 671-0CC02-0YA0 Windows 2000 SP3 or higher

Or operating system supported by STEP V5.2 SP1

User software GS11.zip STEP7 project GS11.mwp

Contained in the file ”20987586_PutGet_S7200_CODE_v10.zip”

Micro/Win project

Example project The user software components include

• STEP7 project “GS11.zip” ○ Hardware configuration ○ Connection configuration ○ Immediately executable user program (STL) ○ Operator interface (variable table)

• Micro/Win project “GS11.mwp“ ○ Immediately executable user program ○ Operator interface (variable table)

Chapter 4.2 “Installation of the software” includes installation instructions.


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3 Function Mechanisms and Program Structures

3.1 Core properties of the S7 protocol and its services

Physical independence of the S7 protocol The S7 protocol is a physically independent protocol. It allows connections between two partners via the following physical networks:

▪ MPI ▪ Industrial Ethernet ▪ Profibus.

Position of the S7 protocol in the ISO OSI reference model

Fig. 3-1

In the ISO / OSI 7 layer reference model for communication, the S7 protocol itself is located on level 7, as the used interface of the system is merely based on application data. Services for managing the connections or for converting the data are not necessary as they are provided by functions of the operating system.


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Basic performance data of the S7 protocol services From a user point of view, the S7 protocol consists of the following services:

• PUT / GET

• BSEND / BRCV

• USEND / URCV The table below contains an overview of the respective performance data for the S7 families. The colored service is the service dealt with in this Getting Started; it will be described in detail in the following.

Table 3-1

Services / Features

PUT / GET BSEND / BRCV USEND / URCV

Max. data length S7-300 / S7-400

164 bytes / 400 bytes1)

32 KB / 64 KB 2) 440 bytes / 440 bytes1)

Possible address areas

M, D / M, T, Z, E, A, D

M, D / M, T, Z, E, A, D

M, D / M, T, Z, E, A, D

Data consistency S7-300/-400

8 – 32 bytes / 32 bytes to total length 3)



Communications principle

Client / Server Client / Client Client / Client

Max. number of connections

See CPU specification



Block types SFB / FB 15 ”PUT“ SFB / FB 14 ”GET“

SFB / FB 12 ”BSEND“ SFB / FB 13 ”BRCV“

SFB / FB 8 “USEND“ SFB / FB 9 ”URCV“

1) Corresponds to the total size of the user data for the SFB / FB in case of Industrial Ethernet.

2) Corresponds to the maximum length of a data block of the respective system.

3) Depending on the CPU used.

3.2 Configuration of an S7 connection

The S7 protocol is based on fixed configured connections which were stored in the programmable logic control. One as well as several connections can be configured for one connection partner. The following connection configurations are possible and can be used by the following services:


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Overview

Table 3-2 Belo Below, a brief overview of both configuration types is given to illustrate the structure in the programmable logic controls.

Unilaterally configured connection Unilaterally configured connection refers to a connection which was exclusively stored on the active side in the configuration (WinAC base station in our example). Based on this principle, a fixed connection resource for the communication is only assigned on the “active” side. The “passive“ side reacts to the requests of the active partner and thus only requires a resource if that partner establishes a connection. A unilaterally configured connection can be used exclusively for write – read services. These services are realized in the S7 as “PUT“ and “GET“. Unilaterally configured connections are used for client-server communications.

Bilaterally configured connection Configurations in which both connection partners have created a fixed connection between each other in the connection configuration (client-client connection) are considered bilaterally configured connections. This is also independent of whether both partners possibly exist in the same project. The connection configuration causes both communication partners to reserve a fixed connection resource for this communication, irrespective of whether the communication partner is physically approachable or not. Two different services are available for bilaterally configured connections, an uncoordinated (USEND / URECEIVE) and a block-orientated (BSEND / BRECEIVE) send / receive service.

Service Configuration PUT / GET (Read / Write) Unilaterally configured connection

USEND / URECEIVE Bilaterally configured connection BSEND / BRECEIVE Bilaterally configured connection


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3.3 User interface PUT / GET

In this Getting Started, the “PUT/GET“ service is used as user interface for the S7 protocol. “PUT/GET“ is a unidirectional write / read service for the transmission of small aggregates between two stations.

SFB15 “PUT” The figure below shows the parameterization of the SFB15 “PUT“ block.

Fig. 3-2 The individual parameters will be described in the following.

Table 3-3

Parameters Declaration Description

REQ IN Activates the data exchange in case of positive edge.

ID IN Connection ID is taken from the connection configuration.

DONE OUT Positive edge on DONE indicates the error-free execution of the function.

ERROR OUT Together with the parameter STATUS, the status parameter ERROR indicates an error.

STATUS OUT Delivers a warning if ERROR = 0 or detailed information on the type of the error if ERROR = 1.

ADDR_i IN-OUT Pointer on those areas in the partner CPU onto which is to be written.

SD_i IN-OUT Pointer on those areas in own CPU which contain the data to be sent.


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SFB14 “GET” The figure below shows the parameterization of the SFB14 “GET“ block.

Fig. 3-3

The individual parameters will be described in the following.

Table 3-4

Parameters Declaration Description

REQ IN Activates the data exchange in case of rising edge.

ID IN Connection ID is taken from the connection configuration.

NDR OUT Positive edge on NDR indicates the successful completion of a command.

ERROR OUT Together with the parameter STATUS, the status parameter ERROR indicates an error.

STATUS IN-OUT Delivers a warning if ERROR = 0 or detailed information on the type of the error if ERROR = 1.

ADDR_i IN-OUT Pointer on those areas in the partner CPU which are to be read.

RD_i IN-OUT Pointer on those areas in own CPU in which the read data are to be stored.


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3.4 Principle structure of this example

Introduction This example illustrates in a simple manner how data from one of three different source areas on a programmable logic control can be transferred into a target area in a remote programmable logic control via one S7 connection. The following data flow model illustrates the sequence realized in this example.

Data flow model

Fig. 3-4

Description of the sequence The data transmission is started when the server CPU requests a new data record by means of a request bit. Using a “GET” call, the client cyclically polls whether there is a request. If this is the case, SFB15 “PUT“ is called on the client side; SFB15 “PUT“ is parameterized with a pointer on one of the three DBs (101, 102 or 103) depending on the requested data record. The connection ID (R_ID) is identical in each case. SFB “PUT“ writes the data record into the target area (DB1) of the server CPU.


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3.5 Program structures

This chapter describes the program structure of the example with regard to the function and data block level of the automation system.

Representation block structure The figure below illustrates the call hierarchy of all blocks used in this example as well as the access to the data blocks used.

Fig. 3-5

Description block structure Only DB1 is displayed on the server side, since there is only one passive interface which the client accesses. On the client side, FC1 “COMMUNICATION“ is called cyclically by OB1 which cyclically calls SFB14 “GET“ to access the passive bit interface of the server. That way, the client determines whether there is a request for a new data record. Due to the call of SFB15 “PUT“, the requested data record is subsequently sent into DB1 of the server,


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OB35 is called at intervals of 1000ms and provides the trigger for the cyclic polling of the server’s bit interface in order in order to check whether there is a request. The actual polling takes place in OB1.

Data blocks used

Table 3-5

Name Application Client

DB2 “ERROR_LOG“ If an error occurs during the execution of the functions PUT or GET, the function status is stored in this DB.

DB14 Instance DB for SFB14

DB15 Instance DB for SFB15

DB101 “DATA_RECORD1“

Contains the first data record


Contains the second data record


Contains the third data record

Server

DB1 Variable area of the S7-200 CPU. In this example, it contains 3 bytes functioning as passive communication interface as well as 100 bytes memory space as target area for the received data.


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3.6 Program flow in the client station

Flowchart The flowchart below shows the program flow on the client side. The communication functionality is integrated in FC1 “COMMUNICATION“ which is called cyclically by OB1. FC1 is realized as single interface.

Table 3-6

Flowchart Explanation

First, the request bit of the server station is read using the “GET“ function and it is checked whether there is a request. This process is repeated until a request is detected. Subsequently, an Any pointer is created which points to the requested data record. This pointer is then used during the call of the “PUT“ function to send the data record to the server. Sending the data record is effected asynchronously, i.e. the function is called until a bit indicates the completion of the function. If the data record was sent without errors, the server receives an “OK bit“ as acknowledgement.


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Code excerpt FC1 “COMMUNICATION” – call of the GET function

The following code excerpt is responsible for the so-called “polling” of the communication partner: Once a second, a new read request determining whether a request for a data record exists in the partner is triggered with the positive edge on “REQ“.

Fig. 3-6

The read procedure is started with a positive edge on this bit once a second.

.
TRUE indicates that the function has been completed
Indicates which bytes of the partner CPU (S7-200) are to be read.
Receive area on the local CPU (WinAC) in which the readdata are to be stored. In case of an error, the status of the function is stored in aDB and the function is completed. If there is a request of the server (read in M 0.7), the
“RequestFrom Server“ bit is set.

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Code excerpt FC1 “COMMUNICATION” – call of the PUT function

In the following code excerpt, the requested data record is sent to the partner CPU.

Fig. 3-7

T

A positive edge is required after a null run in order to start the write procedure.

Target area for the data record in the partner CPU

his data record is to be sent to the partner CPU.
In case of an error, the status of the function is stored ina DB and the function is completed. If the execution of the function is completed, the nextstep is started.
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Code excerpt FC1 “COMMUNICATION ” – sending the acknowledgement In the following code excerpt, the acknowledgement is sent to the partner CPU.

Fig. 3-8

3.7 Server interface

Functionality A program is not requireinterface in the variable

Table 3-7 Symbolic name A

Request V

DataRecord V

OK V

The write procedure is started after the function at the REQ input receives the value TRUE after a null run.

Target area for the OK bit in the partner CPU (server)

This byte contains the OK bit and is to be sent to the partner CPU (server).
In case of an error, the status of the function is stored in aDB and the function is completed.
dar

d

0

B

2

If the execution of the function is completed, the next step is started.

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on the side of the server, there is only a passive ea (DB1) which is set up as follows:

dress Explanation

.7 If this bit is set to TRUE, a new data record request is made.

1 Specifies the number of the requested data record (here: 1, 2 or 3).

.6 This bit is set to TRUE by the client, if the transmission of a data record was complete and error-free.


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4 Installation of Hardware and Software

4.1 Hardware configuration

The components of the hardware configuration are listed in chapter 2.1 “Required components”.

Table 4-1

Step Action

1 Connect the MPI interface of the PG to the MPI interface of the CPU via the MPI cable.

2 Supply power to the CPU.

4.2 Installation of the software

Standard software At this point, we will not go into the installation of STEP7, Micro/Win and WinAC. The installation takes place in the familiar Windows environment and is self-explanatory.

Setting the PG/PC interface Before the project can be loaded into the control, the PG/PC interface has to set according to the steps described below.

Tabe 4-2

Step No. Action Screenshot / Note

1 Open the SIMATIC Manager. 2 Open the dialog box of the same name via the

Options > Set PG/PC Interface menu and set “PC internal (local)” as access point of the application.

3 Acknowledge the dialog box with "OK".


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Configuring WinLC station You have to configure the PC station before you can load the STEP7 project into the WinLC. This requires the following steps:

No. Action Screenshot / Note 1 Start the station configurator via

Start > Station Configurator.

2 Make sure that the component

WinLC is entered on slot 2 and that CP5611 is entered on slot 3.

In accordance with the hardware configuration of the STEP7 project.

3 Click Station Name.

4 Enter SIMATIC PC-Station.

Note These steps have to be performed prior to the start of the WinLC.


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Loading the STEP7 project In order to load the STEP7 project into the WinAC controller, proceed as follows:

Table 4-3

Step No. Action Screenshot / Note

1 Retrieve the file 20987586_PutGet_S7200_CODE_v10.zip into a user-definable directory.

This zip-file contains the files GS11.zip and GS11.mwp.

2 Start the WinAC controller via Start > SIMATIC > PC Based Control > WinLC.

3 Retrieve the project via the File > Retrieve... menu

Search for the GS11.zip project using the browser function and acknowledge with OK.

4 Select a directory into which the project files are to be retrieved.

After retrieving you are asked whether you wish to open the project with Step 7, acknowledge this query with Yes.

5 After opening the project, open the project tree of the project.

6 Click SIMATIC PC-Station in the project tree and

load the program into the WinLC controller via or PLC > Download.

7 Switch the WinAC controller to RUN.


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Loading the MicroWin project In order to load the Micro/Win project into the S7-200 CPU, proceed as follows:

Table 4-4

Step No. Action Screenshot / Explanation

1 Open the Micro/Win project GS11.mwp. 2 Open the dialog box of the same name by

clicking the “Communications“ button and make sure that Micro/Win has an access point to the control via CP5611(PROFIBUS).

Define the settings as illustrated below.

3

Click or the File > Download menu item.

The program is loaded into the control.

4 Set all checkmarks in the following dialog box and acknowledge this dialog box and the two following dialog boxes with OK.

5 Switch the S7-200 CPU to RUN.

4.3 Core configurations of the application

Connection configuration The application on hand receives a fixed configured connection which is required by the PUT/GET S7 communications service used here. The table below shows how to configure such a connection.


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Note The following connection configuration is already contained in the project. The purpose of the configuration instructions is to familiarize with the procedure.

Table 4-5 Step Action

1 Open the STEP7 project GS11, click GS11 in the project tree and open NetPro by clicking the MPI network.

2 Select WinLC.

3 Select Insert > New Connection. 4 In the following dialog box select

- Connection Partner: unspecified - Connection Type: S7 connection

5 Acknowledge with OK. 6 Edit the following dialog box as shown in the screenshot.

Step Action

7 Acknowledge the dialog box with OK and save and compile the connection

configuration by clicking or with the menu item Network > Save and Compile.


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4.4 Operator control and monitoring

Introduction The application is operated and monitored via the variable tables contained in the example.

Activating the variable tables In order to be able to control and monitor the process, activate the variable tables as follows:

Note Requirement: The steps described in chapter 4 “Installation of Hardware and Software” have been performed.

Table 4-6

No. Description

1 Open the STEP7 project GS11 and open the variable table VAT_1 in the block folder by double-clicking.

2 Select the menu item Variable > Monitor or click .

3 Open the Micro/Win project GS11.mwp and open the variable table CHT1 by clicking the Status Chart button.

4 Select the menu item Debug > Chart Status

or click . 5 Now you can monitor both variable tables and modify values.


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Variable table in the client

Fig. 4-1

Meaning of the variables (client) The variables have the following meaning: Symbol Meaning

LookForRequest This bit is set once per second and used as trigger for the polling of the server station. In every rising edge it is checked whether there is a request.

RequestFromServer TRUE: There is a request from the server.

DataRecordNumber Number of the requested data record

DataBlockNumber Number of the DB in which the required data record is located.

DONE_put

ERROR_put

STATUS_put

Return value of the “PUT“ function. For details, see chapter 3.1.2 “User interface for this protocol”.

NDR_get

ERROR_get

STATUS_get

Return values of the “GET“ function. For details, see chapter 3.1.2 “User interface for this protocol”.

STEP1

STEP2

STEP3

The function FC1 “COMMUNICATION” is executed as sequence chart. These bits indicate which step is currently active.


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Variable table in the server The figure below shows the variable table CHT1 of the Micro/Win project.

Fig. 4-2

Meaning of the variables (server) The variables have the following meaning: Symbol / Address Meaning

OK If this bit has the value 1, the respective data record has been received without errors upon the last request.

Request A positive edge on this bit represents a new data record request.

DataRecord It can be indicated which data record is to be requested (data record 1, 2 or 3 in our example).

VB3, VB4, .....VB102 The client writes the requested data into this memory area.


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Modification of the data transfer You can start the data transfer process from client to server according to the steps listed below.

Table 4-7

No. Action Figure / Result

1 Open the status chart CHT1 of the Micro/Win project.

2 Enter e.g. the value 3 for “DataRecord“ into the “New Value“ column and set “Request“ to 1. Note: Only the values 1, 2 or 3 may be entered for “DataRecord“.

3 Click or in the menu Debug > Write all.

The values are accepted into the control.

4 Click or in the menu Debug > Single Read.

Now, you see that the requested data were received. The OK bit indicates that the send procedure was completed without errors and completely.

5 Modify the “OK” bit and the “Request” bit back to 0 before you transmit a new request.

Documents

Application for Communication - Siemens · PDF fileWinAC Basis and S7-200 Stations via S7 Communication ... S7-300 / S7-400 164 bytes / 400 ... BSEND / BRECEIVE Bilaterally configured