OPC Device Support |
last Modified: by kuner |
• Author : Kuner, Winkler
The OPC device driver provides direct access for EPICS records to items located on an OPC server. It has the following features:
• 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.
• Setup the OPC client with special features:
• Error logging using the iocLogClient.
• Available console commands for debugging purposes:
• The windows installable will install these files (full installation):
C:\Program Files\OpcIocShell\ readme.html startDemo.bat unins000.dat unins000.exe bin\ asIoc.dll ca.dll caget.exe camonitor.exe caput.exe caRepeater.exe Com.dll dbIoc.dll dbStaticIoc.dll dbtoolsIoc.dll gdd.dll Icons.dll iocLogServer.exe iocsh.dll miscIoc.dll MSVCP60.DLL MSVCP60D.DLL MSVCRT.DLL MSVCRTD.DLL OpcIoc.exe recIoc.dll registryIoc.dll rsrvIoc.dll SOCltadd.DLL SOCmnadd.DLL SODaCadd.DLL softDevIoc.dll dbd\ iocShell.dbd demo\ DemoRecord1.db DemoRecord2.db st.cmd src\ Creator.cpp Creator.h cthread.h devOpc.c devOpc.h drvOpc.cpp drvOpc.h errDbg.cpp errDbg.h Group.cpp Group.h iocShellMain.cpp Item.cpp Item.h Makefile O.win32-x86 Opc.cpp Opc.h opcConsoleCmd.cpp opcConsoleCmd.h readme.txt Server.cpp Server.h StdAfx.h
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 is neccessary. We use OPC Toolkit version 3.01. To run the example, "MMI OPC" OPC-server simulator should be installed. It comes with the "OPC Explorer" from MMI OPC .
Used to control the output of debugging information. The default is 0 to be completely quiet. More informations via "help opcDbg".
• Syntax :
opcDbg(n_debugLevel)
• Parameters :
Create a report of all records that use OPC device support. Output format:
epicsName, Record Type, Dtype, opcName, opcFullName
• Syntax :
opcIor
There is a special way to add groups and items to an OPC server. The st.cmd file is more than the commands of the iocShell. It is also parsed by the opc interface routine! The idea is to have one file to setup the iocShell and also the opcClient. See the example:
• Example : of an st.cmd that shows the OPC client setup:
iocShell_registerRecordDeviceDriver(pdbbase) opcSetNames("../names.txt") opcSetServer("localhost","MMIOPC.Simulator") opcSetGroup("myGroup3seconds","3000") dbLoadRecords("./DemoRecord1.db") opcSetGroup("myGroup6seconds","6000") dbLoadRecords("./DemoRecord2.db") iocShell_registerRecordDeviceDriver(pdbbase) iocInit()
Used only in st.cmd, not from the command line. It configures iocShell for connecting to OPC server.
It's possible to connect iocShell to miscellaneous OPC servers.
• Syntax :
opcSetServer("hostName", "serverName")
• Parameters :
Used only in st.cmd, not from the command line. It creates a new OPC item group at current OPC server. It's possible to create miscellaneous groups with several update rates at same server. According to the OPC "Data Access" specification it is mandatory to define at least one group.
• Syntax :
opcSetGroup("groupName","n_scanRate")
• Parameters :
Used only in st.cmd, not from the command line. It sets 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 # don't forget a blank line at end of file
• Syntax :
opcSetNames("fileName")
• Parameters :
This example shows how to set up an IOC
# Make sure that the dbd contains the lines for "opc" and "opcRaw" dbLoadDatabase("./iocShell.dbd",0,0) iocShell_registerRecordDeviceDriver(pdbbase) # registerRecordDeviceDriver(pdbbase) <= old command, won't work with epics base 3.14.6 and higher!!! # # Name mapping is not required here # opcSetNames("../names.txt") # # This example uses the "MMI OPC" OPC-server simulator at local host opcSetServer("localhost","MMIOPC.Simulator") # very slow group, scanning every 3 seconds opcSetGroup("myGroup3seconds","3000") dbLoadRecords("./DemoRecord1.db") # # very slow group, scanning every 6 seconds opcSetGroup("myGroup6seconds","6000") dbLoadRecords("./DemoRecord2.db") # iocInit()
• 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 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.
Record | DTYP | 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 | opc | ? | ||
mbbo | opcRaw | ? further experimets will give new and exciting information, | ||
mbbiDirect | opc | ? what this records does! See next version. | ||
mbbiDirect | opcRaw | ? mbboDirect | opc | ? |
longin | opc | no conversion | ||
longout | opc | no conversion | ||
stringin | opc | no conversion stringout | opc | no conversion |
waveform | opc | no conversion |
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:
/src/libCom/logClient.h /src/libCom/logClient.c 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 an iocShell following occures:
It seams to be a problem of the Windows task priorities. Solution:
see section "Record scanning " - Out Records