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Page last modified 19:30, 13 Dec 2014 by daguiam

EPICS & Siemens PLC Tutorial

    Version as of 23:39, 5 Apr 2025

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    Table of Contents 

    1. 1. EPICS testS7 IOC Setup Tutorial
      1. 1.1. Intro
      2. 1.2. System Setup
        1. 1.2.1. Hardware Platform
        2. 1.2.2. Software Platform
      3. 1.3. Getting Started
    2. 2. testS7 IOC Example Application
      1. 2.1. Records Database File
        1. 2.1.1. Poll Groups
      2. 2.2. Sequencer Program

    EPICS testS7 IOC Setup Tutorial

    Intro

    The ESTHER Slow Controller system controls the gas injection into the combustion chamber of the shock tube. This system uses the EPICS framework to communicate with a Siemens SIMANTIC S7-1200 PLC using the Open Source EPICS Device Support Library s7nodave. A Control System Studio graphic user interface client is used to visualize and control the whole experiment by connection with the EPICS IOC server.

    This tutorial is presented as a reference to setup a server computer running an EPICS server that connects to the S7 PLC. An example EPICS IOC "testS7" application and accompanying CSS interface are provided. This example application allows the control and observation of all digital IO and analog inputs of the connected S7-1200 PLC.

    System Setup

    Hardware Platform

    The requirements to setup this testS7 application are:

    1. A computer running a 32-bit Operating System (a 32-bit operating system is required to implement polling groups using the s7nodave device support library in EPICS). Two ethernet cards (One connected to the local network without internet access where the PLC is present).
    2. A Siemens SIMANTIC S7-1200 PLC powered with 24 VDC.
    3. A client computer running the CSS interface.

     

    The setup used for this tutorial was:

    1. A Supervisor EPICS server:
      1. Virtual Machine running Debian GNU/Linux 7.7.0 32-bits
      2. Linux Kernel 3.2.0-4-486
      3. Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
      4. 512 MB RAM
      5. Two Bridged Intel Corporation 82540EM Gigabit Ethernet Controllers
        1. eth0 connected to IPFN network with IP 10.136.237.21 subnet 255.255.0.0 (with internet access)
        2. eth1 directly connected to the S7-1200 PLC with IP 192.168.0.70 subvnet 255.255.255.0 (without internet access)
    2. ​A Siemens SIMANTIC S7-1200 PLC powered at 24 VDC using an external power supply and connected to the eth1 of the Supervisor EPICS Server with IP 192.168.0.1 subnet 255.255.255.0.
    3. A client computer running CSS on the IPFN network 10.136.xxx.xxx subnet 255.255.0.0.
    4. A computer running a Windows Operating System with the Siemens Totally Integrated Automation (TIA) PLC programming software packaged installed to develop and program the PLC firmware.

    Software Platform

    All the software required for this test application is located in the IPFN ESTHER SVN repository: http://metis.ipfn.ist.utl.pt/svn/cdaq/ESTHER/Software/

    EPICS IOC: http://metis.ipfn.ist.utl.pt/svn/cdaq/ESTHER/Software/EPICS/IOC/testS7/

    PLC Firmware: http://metis.ipfn.ist.utl.pt/svn/cdaq/ESTHER/Software/TIA/S7-1200/testS7_PLC/

     

    Getting Started

    Setup Supervisor Example EPICS Server

    1. Install clean Debian 7.7.0 32-bit distribution on a computer or virtual machine with bridged network adapter
    2. Compile EPICS Base:
      1. Follow the Getting Started of http://epics.nsls2.bnl.gov/debian/
      2. apt-get install epics-dev build-essential
      3. apt-get install epics-synapps-dev epics-iocstats-dev visualdct openjdk-6-jdk sysv-rc-softioc
      4. The latest EPICS base version is then installed to /usr/lib/epics
    3. Install s7nodave device support library
      1. cd /opt/epics/modules
      2. wget -c http://oss.aquenos.com/epics/s7nodave/download/s7nodave-1.0.3.tar.gz -O - | tar -zx
      3. cd s7nodave-1.0.3/
      4. vi configure/RELEASE
      5. Replace "EPICS_BASE=/usr/lib/epics" or add to the end of the file
      6. Save and exit
      7. Install libboost if needed: apt-get install libboost-all-dev
      8. make
      9. cd ..
      10. Create symbolink link to folder: ln -s ./s7nodave-1.0.3/ s7nodave
    4. ​Install the EPICS state-machine sequencer library
      1. ​wget -c http://www-csr.bessy.de/control/SoftDist/sequencer/releases/seq-2.1.17.tar.gz -O - | tar -zx
      2. cd seq-2.1.17/ 
      3. vi configure/RELEASE
      4. Replace "EPICS_BASE=/usr/lib/epics" or add to the end of the file
      5. Install lexer generator tool re2c: apt-get install re2c
      6. make
      7. cd ..
      8. Create symbolink link to folder: ln -s ./seq-2.1.17/ seq
    5. Add testS7 project from the SVN repository
      1. apt-get install subversion
      2. svn co http://metis.ipfn.ist.utl.pt/svn/cdaq/ESTHER/Software/EPICS/IOC/testS7/
      3. cd testS7/
      4. Set the correct library dependencies for the modules:
        1. vi configure/RELEASE
        2. Replace or add "SNCSEQ=/opt/epics/modules/seq"
        3. Replace or add "S7NODAVE=/opt/epics/modules/s7nodave"
        4. Replace or add "EPICS_BASE=/usr/lib/epics"
        5. Save and exit
      5. ​make
    6. Execute the testS7 example IOC
      1. cd iocBoot/ioctests7/
      2. chmod +x st.cmd
      3. ./st.cmd

     

     

     

    testS7 IOC Example Application

    The EPICS testS7 IOC Application consists in the following sections inside the [testS7] root folder:
    • A database file containing the records of the process variables for the expected IOC application. These are in the [testS7]/tests7App/Db/dbS7.db file.
    • The state-machine sequencer program that is located in the [testS7]/tests7App/src/snctests7.stt file.
    • The EPICS executable startup script in [testS7]/iocBoot/ioctests7/st.cmd

    Records Database File

    In this example IOC application, all the available S7-1200 PLC digital and analog IO are set in the application database records in the file [testS7]/tests7App/Db/dbS7.db.
    The standard S7-1200 PLC contains 10 digital outputs ports, 14 digital inputs ports and 2 analog inputs ports.
    The digital inputs and outputs can only have the values 1 or 0 and must be read by the IOC application using a binary in (bi) or written to using a binary out (bo) record.
    A PLC digital input port can only be read and not written to, so only a bi record is set in the IOC application database.
    A PLC digital output port can be both read and written to. This means that to read the status of the PLC digital output, the IOC application must use the bi record for that PLC port. And to set the status of that port, the IOC application must use the corresponding bo port.
    The mnemonic to consider here is that the bi and bo records correspond to what is being read or written by the IOC application, and not the PLC.
     
    In the case of the S7-1200 PLC, the port is for each record is defined by setting the value "@myPLC Q0.1" in the INP or OUT fields, for example. In this case the "myPLC" value is the alias given to the PLC in the [testS7]/
    iocBoot/ioctests7/st.cmd file (s7nodaveConfigureIsoTcpPort("myPLC", "192.168.0.1", 0)), and the Q0.1 corresponds to the digital output group 0, bit 1.
     
    The S7-1200 PLC have the following address aliases:
    Digital Outputs (prefix Q):
    Group 0 bit 0 -> Q0.0
    ...
    Group 0 bit 7 -> Q0.7
    Group 1 bit 0 -> Q1.0
    Group 1 bit 1 -> Q1.1
    Digital Inputs (prefix I):
    Group 0 bit 0 -> I0.0
    ...
    Group 0 bit 7 -> I0.7
    Group 1 bit 0 -> I1.0
    Group 1 bit 6 -> I1.5
    Analog Inouts:
    Analog Input 0 -> IW64
    Analog Input 1 -> IW66
     

    Poll Groups

    All the input records in the database have a SCAN field. The IOC application will scan the value of each record at the interval defined in the SCAN field. For a SCAN field of "0.1 second" of a input record, the IOC application will query the PLC for that record's value once every 100 miliseconds.
    However, EPICS treats each query independently, so by setting the SCAN field of every input record in this way, EPICS will query each value thorugh the local network and wait for the response before moving on to the next query, resulting in delayed responses.
    The s7nodave library allows records to be assinged to polling groups. All the records in a pollgroup are queried in the same network packet, greatly reducing response lag.
    In order to assign an input record to a poll group using the s7nodave library, one must set the SCAN field to "I/O Intr", and the INP field to "@myPLC(PG=[POLLGROUP_NAME]) [PLC_ADDR]". This can be seen in the example below for the PV S7:biI1_5poll.
    record(bi, "S7:biI1_5poll")
    {
            field(SCAN, "I/O Intr")
            field(DTYP, "s7nodave")
            field(INP, "@myPLC(PG=1s) I1.5")
            field(DESC, "S7 PLC I1.5 Binary Input POLLING")
    }
    Ommiting (PG=[POLLGROUP_NAME]) will assign the PV record to the "default" poll group.
     

    Sequencer Program

    The example sequencer program inside this testS7 is a simple state-machine that monitors the value of a PLC port and sets another port to high or low accordingly. This program sequencer can be seen below:

    program snctests7

    double v;
    short light;
    assign v to "S7:biQ1_0";
    monitor v;
    assign light to "S7:boQ0_7";
    ss ss1 {
        state init {
    when (delay(1)) {
       printf("snctests7: Startup delay over\n");
       printf("snctests7: Going to low\n");
    } state low
        }
        state low {
    when (v >= 0.5) {
    printf("snctests7: Changing to high %f\n",v);
    light = TRUE;
    pvPut(light);
    } state high
        }
        state high {    
        when (v <= 0.5) {
    printf("snctests7: Changing to low %f\n",v);
    light = FALSE;
    pvPut(light);
    } state low
        }
    }
     

     

     

     

     

     

     

     -------- IGNORE --------


    1. Download EPICS Base R3.14.12 or higher:
      1. Most recent: http://www.aps.anl.gov/epics/download/base/index.php
      2. Or: http://www.aps.anl.gov/epics/download/base/baseR3.14.12.4.tar.gz
    3. Compile EPICS
      1. Dependencies:
        1. apt-get install g++
        2. Follow the Getting Started of http://epics.nsls2.bnl.gov/debian/

        3. apt-get install epics-dev build-essential

        4.  

     

      1. cd /tmp/

      2. wget -c http://www.aps.anl.gov/epics/downloa...14.12.4.tar.gz -O - | tar -zx

      3.  

        cp -r base-3.14.12.4/ /usr/lib/epics/

      4. cd /usr/lib/epics/

      5. export EPICS_HOST_ARCH=$(perl startup/EpicsHostArch.pl) 

      6. make clean uninstall
      7. make 
      1. Install Asyn driver
        1. mkdir /opt/epics
        2. mkdir /opt/epics/modules
        3. cd /opt/epics/modules
        4. wget -c http://www.aps.anl.gov/epics/downloa...syn4-24.tar.gz -O - | tar -zx
        5. cd asyn4-24
        6. ech

       

    3.  
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