Kepco BOP PSU: Investigate communications issue seen on Muon Zerofield system [Timebox: 2 days]

[davidkeymer]

As a muon (or neutron) instrument scientist, I would like the communications with my Kepco BOP PSU to be reliable.

While investigating recent zerofield issues seen on MuSR, it was discovered that the PSU occasionally sent (or a reply was misinterpreted) an invalid setpoint. e.g. actual setpoint: 0.74, readback: 9.74.

Acceptance criteria

• Source of communications problem is found
• Any resultant work is split out into further tickets

Notes

• Link to original support issue
• Zerofield tickets for more details: Muon Zerofield System: Add check to Setpoint Readback from PSUs #7715 Muon Zerofield System: Add maximum Current setpoint ramp rate  #7716
• Suggest removing the ExtraInput = Ignore; from the Kepco protocol file. Also see this ticket for more information.
• Enable I/O tracemasks and write output to file for later analysis
• Check whether or not the LabVIEW driver shows this behaviour
• Consider use of *OPC as well (see comment)

[KathrynBaker]

From Ticket #7719

As a developer I would like to remove ExtraInput = ignore from the kepco protocol https://github.com/ISISComputingGroup/EPICS-kepco/blob/master/kepcoApp/protocol/kepco.proto as it potentially increases the chance of a corrupt reply being interpreted as a good one.

We may also want to consider adding ;*OPC? to the end of set commands which should return 1 when it completes, however i might have already tries this and found our cards did not support it

[davidkeymer]

Impeded until can get an opportunity to test the suggested changes to the Kepco protocol file.

[FreddieAkeroyd]

One of the kepcos giving issue was right on the full/quarter range point - as additional accuracy not needed have added #7945 as this continued switching may cause a delay?

[FreddieAkeroyd]

ISISComputingGroup/EPICS-kepco#22
ISISComputingGroup/EPICS-ZFCNTRL#19
ISISComputingGroup/EPICS-DeviceEmulator#173
ISISComputingGroup/EPICS-IOC_Test_Framework#608
ISISComputingGroup/EPICS-ioc#807
ISISComputingGroup/EPICS-zfmagfld#8
ISISComputingGroup/ibex_gui#1668

Release notes #8325

ISISComputingGroup/EPICS-DAQmxBase#9 already merged

[rerpha]

has this been patched onto MuSR? if so, it should be added here https://github.com/ISISComputingGroup/IBEX/wiki