MuSR: 3He Refrigerator Testing

[JamesKingWork]

As a MuSR scientist, I would like the 3He Refrigerator IOC to be sufficiently tested against hardware.

Acceptance criteria:

• Test plan and outcomes are documented in this ticket
• Communications to the device is tested against hardware
• Control logic of the IOC is tested against hardware

Notes:

• The 3He refrigerator is a Heliox/ITC503 based system
• LabVIEW VIs are at C:\LabVIEW Modules\Oxford Software\Muon Heliox

3He Refrigerator tickets:

• Document VI control logic: MuSR: 3He Refrigerator Document VI Cryogenic Control Logic #6239
• Implement control logic: MuSR: 3He Refrigerator Implement Cryogenic Control Logic #6240
• Communications: MuSR: 3He Refrigerator Communications #6241
• OPI: MuSR 3He Refrigerator OPI #6244
• Machine setup: MuSR: Discuss 3He Refrigerator Machine Setup #6242
• Testing on Device: MuSR: 3He Refrigerator Testing #6243

[JamesKingWork]

They do want to use this for the upcoming cycle and cryogenics have confirmed that they can set up the machine shortly after the software is completed

[JamesKingWork]

Impeded waiting on #6294 and #6240. We could do an initial test after the communications are reworked and then test the autocondense separately

[JamesKingWork]

The testing for this device is currently being postponed to enable EMU mercury itc and MUSR soak testing

[JamesKingWork]

The current plan is to move back to SECI if this device is needed in the next cycle. Removing it from the board and impeded, will propose again when MUSR want to test

[rerpha]

so far we have been working on
OPI: https://github.com/ISISComputingGroup/ibex_gui/tree/Ticket6243_hardware_testing
support: https://github.com/ISISComputingGroup/EPICS-hlx503/tree/field_test_fixes
IOC: ISISComputingGroup/EPICS-ioc#688

[rerpha]

we may need to use #7143 if possible as the state machine seems to be sending commands in sequence too quickly!

[rerpha]

OK, there was a race condition that was causing things to happen in no given order when setting a SP (though mostly just the sorb SP) which was caused by DLYs in sseq that called other sseq records with the same delay, ie

sseq1
 - set this pv
 - delay 0.1 seconds
 - do sseq2 
 - delay 0.1 seconds 
 - set another pv    <---- this might happen before sseq2 finishes as the delay is the same inbetween sseq

sseq2
- set this pv
- delay 0.1 seconds 
- etc

I have bodged this for now by setting the outer delay to be longer (0.5) than the inner delays (0.1 each) added up in total, and this seems to work quite nicely. I don't want to change this without another opportunity to test with hardware but we should probably do something like use a WAITn instead - though this might not wait for the nested sequence to finish which would be something else to test.

[rerpha]

im going to be a bit cheeky and merge the above branches into master so we can have a built copy in case my copied-over version does not work in the morning. hopefully the build completes!

[rerpha]

in a nutshell, everything seemed to work and we managed a recondense as well as skipping through the first part of a recondense. setting setpoints for sorb/he3 pot now work well. I will be setting up on WISH today so will put this in review once they are happy

[rerpha]

repointing - some other things are needed:

• It would be better if the threshold for switching between the HE3POTLO and HE3POTHI thermometers was separate to the threshold used for switching between high and low temperature mode. I think we discussed this when we implemented the thermometer switching, but ended up using the same threshold for speed. Unfortunately this didn’t work out during real usage.
• There are a lot of communications drop outs for some reason which causes the reported temperature to drop down to zero.
• The switching the heater off every time a new setpoint is sent is messing up the PIDs, causing very noticeable temperature drops and hence time delays each time the setpoint is changed (again, see graph).

[rerpha]

actually, i will create a new ticket for this, as the hardware testing has now happened and the other things can be considered separate tasks.

Reviewing this one won't really require much reviewing as WISH used the sorb but would like some tweaks made. I might just close it, but feel free to open it again and review if you disagree

[rerpha]

#7168 is the tweaks ticket