OPC Device Support
last Modified: by kuner
• Author : Kuner
The OPC device driver provides direct access for EPICS records to items located on an OPC server.
• Data conversion for all integer and float data types - array support is not yet implemented.
• Out-records become bidirectional In/Out-records. The EPICS Out-record will be updated if the OPC item is written by another device (e.g. PLC).
• Support for the following record types:
The data conversion capabilities of the binary records (bi, bo, mbbi, mbbo, mbbiDirect, mbboDirect) are supported with two dtypes "opc" and "opcRaw" as described in the Record Reference Manual for the "Soft Channel" and "Raw Soft Channel" types.
• Timestamp is generated by OPC server or EPICS (source is determined by the record's TSE field).
• OPC quality is mapped to record's STAT/SEVR fields.
• Available console commands, to be used in st.cmd or for debugging purposes:
Support for connections to multiple servers and several groups per server is being worked on.
• Error logging using the iocLogClient.
• The windows instalable will install this files :
C:\Program Files\OpcIocShell\ iocShell.dbd iocShell.exe unins000.dat unins000.exe Tools\ iocShell.dbd iocShell.exe unins000.dat unins000.exe src\ Creator.cpp Creator.h Group.cpp Group.h Item.cpp Item.h Makefile Opc.cpp Opc.h Server.cpp Server.h StdAfx.h cthread.h devOpc.c devOpc.h drvOpc.cpp drvOpc.h errDbg.cpp errDbg.h iocShellMain.cpp opcConsoleCmd.cpp opcConsoleCmd.h O.win32-x86\iocShell_registerRecordDeviceDriver.cpp C:\WINNT\system32\ asIoc.dll rsrvIoc.dll registryIoc.dll recIoc.dll miscIoc.dll iocsh.dll gdd.dll dbtoolsIoc.dll dbStaticIoc.dll dbIoc.dll Com.dll ca.dll softDevIoc.dll SOCltad.DLL SOCmnad.DLL SODaCad.DLL
• the .tar : will install the sources only like this:
|../opcApp/src||iocShell and device support|
|../opcApp/Db||a test and demonstration: opcTest.db and opcTest.adl|
|../opcApp/testOpcApp||a console client for opc for opc access without epics|
The OpcApp_2_1.exe should install the precompiled iocShell and its .dll's in a proper way.
For recompilation of the opcIocShell the OPC Toolkit from Softing (http://www.softing.com) is neccessary. We use OPC Toolkit version 3.01.
Used from st.cmd to set the server to connect to.
opcSetServer hostName serverName
* hostName: where the server is hosted * serverName: name of the server
Used from st.cmd to define a group for the OPC items. According to the OPC "Data Access" specification it is mandatory to define at least one group.
opcSetGroup groupName n_scanRate
* groupName: find a reasonable or a fancy name for it * n_scanRate: update rate (in milliseconds) of the OPC items (> 0 ms)
Used from the command line for debugging purposes to see if the connection to the server works and which items are served.
* 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.
Used from st.cmd to set the file for 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>
* fileName: yes, you guess right, but don't forget the path to your file.
Used to control the output of debugging information. The default is 0 to be completely quiet. Try a higher number and be amazed.
* n_debugLevel: number > 0, 0 = quiet
epicsName, Record Type, Dtype, opcName, opcFullName
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
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".
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.
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.
|ai||opc||no conversion: LINR="NO CONVERSION" (record default)|
|ao||opc||no conversion: LINR="NO CONVERSION" (record default)|
|bi||opc||no conversion, VAL may be any value|
|bi||opcRaw||conversion: RVAL=0 -> VAL=0, RVAL>0 -> VAL=1|
|bo||opc||conversion: VAL=0 -> RVAL=0, VAL>0 -> RVAL=1 send RVAL to the hardware|
|mbbi||opc||for VAL=0..15 record is set to the according state. NOBT, SHFT ignored|
|mbbi||opcRaw||if RVAL=xxVL record is set to state xxST. NOBT, SHFT processed|
|mbbo||opcRaw||? further experimets will give new and exciting information,|
|mbbiDirect||opc||? what this records do! See next version.|
The multibit records (mbbo, mbbi, mbboDirect and mbbiDirect) have the fields NOBT and SHFT to select a special part of the 16 bit data input. This is also supported by the device support.
It is possible to choose the timestamp source. Default is the EPICS timestamp, but if the field TSE="-2" the timestamp of the OPC item will be used.
Due to problems with the Windows Socket Library there are two patched files for the EPICS base to make it work:
This patch is neither neccessary if IOC-Logging is not used nor for versions newer than EPICS 3.14.2
If there are more than ca. 1800 PVs running on a iocShell following occures:
It seams to be a problem of the Windows task priorities. We solved it to run our 6000 PVs in two iocShells on two PCs. This works fine.
see section "Record scanning" - Out Records