OPC Device Support

Compile and Install

Prerequisites :

• "Softing OPC-Toolbox 3.01 Client" has to be installed, up to now this is the only supported OPC client library.
• EPICS 3.14.2: host architecture win32-x86
• Compiler: Microsoft VC6.0

Bring up your working environment:

• Set environment variables:

  EPICS_HOST_ARCH=win32-x86
  set PATH=%PATH%;\Softing\OPCToolbox\bin\vc6

• Adapt src/Makefile:

  USR_INCLUDES = -I "\Softing\OPCToolbox\include" \
                 -I ""\Softing\OPCToolbox\opc"
  USR_LDFLAGS += /libpath:"\Softing\OPCToolbox\lib\vc6"

Microsoft Visual Studio may be used. Be sure to set all paths for includes and libraries according to your local installation of EPICS base and the Softing Toolbox.

You need to run make before you can use MS Visual Studio. The make run creates the file iocShell_registerRecordDeviceDriver.cpp

• Known Problem:

First run of make causes error:

  iocShell_registerRecordDeviceDriver.obj : error LNK2001: unresolved
  external symbol ....

• > Run make twice!!

iocShell Console Commands

opcSetServer: Set the OPC server

Syntax:

  opcSetServer  hostName serverName

Parameters:

  * hostName:    where the server is hosted
  * serverName:  name of the server

opcSetGroup: Define a group for the OPC items

Syntax:

  opcSetGroup  groupName n_scanRate

Parameters:

  * groupName:   find a reasonable or a fancy name for it	
  * n_scanRate:  update rate (in milliseconds) of the OPC items (> 0 ms)

opcBrowse: Browse items of the connected OPC server

Syntax:

  opcBrowse n

Parameters:

  * n: maximum depth in the item hierarchy of the server to be browsed.
       Its value depends on the hierarchical structure of the server. Try
       different values to see what's reasonable for your OPC server.

opcSetNames: Item name mapping

The problem is that the record's INP or OUT fields have a limited length for the name of the OPC item. On the other hand, OPC servers can have huge name lengths for those items. So a map file may be defined to map the long OPC server names to short names suited for the record's link field.

The map file format is:

  # allowed are comments and lines like this with leading spaces:
  epicsName=opcName<\n>

Syntax:

  opcSetNames  fileName

Parameters:

  * fileName:  yes, you guess right, but don't forget the path to your file.

opcDbg: Set debug level

Syntax:

  opcDbg  n_debugLevel

Parameters:

  * n_debugLevel: number > 0, 0 = quiet

opcIor: IO report

epicsName, Record Type, Dtype, opcName, opcFullName

Set up an st.cmd for the ioc shell

This example shows how to set up an IOC

  # Make sure that the dbd contains the lines for "opc" and "opcRaw"
  dbLoadDatabase("../dbd/iocShell.dbd",0,0)
  
  # This is the softing demo server on the local host
  opcSetServer("127.0.0.1","Softing.OPCToolboxDemo_ServerDA.1")
  
  # The group with an update rate of 1 second
  opcSetGroup("group1","1000")
  
  # Name mapping is not required here - comment out to set the file name
  # opcSetNames("../names.txt")
  
  registerRecordDeviceDriver(pdbbase)
  dbLoadRecords("../db/opcTest.db")
  iocInit()
  opcIor > opcReport.txt

Record related issues

Record scanning

• In-records

The device support accepts all but "Passive". Due to the update facilities of the OPC group it is not reasonable to define a scan rate faster than the update rate of the group. To get the same scan rate for the record set SCAN="I/O Intr". To allow a slower than the update rate (for whatever reason) the fixed scan rates are supported: SCAN=".1 second" to SCAN="10 second".

• Out-records

As mentioned before out-records are now bidirectional in/out-records. They will be updated to the new value if it is changed on the OPC server by any other way (e.g. the PLC or another OPC client).

For out-records the SCAN field is ignored by the device support and should be set to "Passive". Nevertheless, if the OPC server gets a new value for the OPC item the record will be processed to update the value, send monitors, check for limits, set severities and process forward links.

Writing to the hardware from two sides (EPICS and the hardware covered by the OPC server) at the same time can cause problems.

For values that are frequently written by the PLC a write by the EPICS record will be overwritten in the opc-server by the PLC before it is sent to the PLC from the opc-server. In this case a caput will not be recognized by the PLC!

• This is a behaviour is due to the opc-server and PLC, no bug in the EPICS device support.

Also an EPICS write that follows immediately after a PLC write (very short time), may be discarded by the device support.

Device types and data conversion

There are two types available: DTYP="opc" for all records and the DTYP="opcRaw" for the binary records: bi, mbbo, mbbi, mbboDirect and mbbiDirect. The behaviour of the record is listed below and is according to the desccription of the raw data types in the Record Reference Manual.

For the analog records ai and ao the LINR field determines the data conversion.

   /src/libCom/logClient.h
   /src/libCom/logClient.c