This came up during the V4 introduction at the recent EPICS meeting.
I first thought it's a bug in CS-Studio, but instead it's a limitation in pvaSrv.
Assume an IOC with pvaSrv added to it, take any calc or ai record:
pvget that_record.INP (or INPA for a calc record)
pvget -m that_record
pvget -m that_record.INP (or INPA for a calc record)
-> Don't get a value, instead message(can not monitor a link field, error)
monitorConnect(Status [type=ERROR, message=create dbPvMonitor failed])
Checking the 4.6.0 release of V4, pvaSrv/src/dbPv/[3.14, 3.15]/dbPvMonitor.cpp both check for link fields and refuse to monitor them with this error message.
Fundamentally, 'camonitor' can monitor link fields, and there are some use cases for doing this:
Displays (EDM, CSS, ..) sometimes need to put 'INP' links on the display so that users can change the input.
The CSS EPCIS PV Tree tool monitors input links to show the link hierarchy.
Is monitoring link fields supported in QSRV?