[Dsg-hallb_magnets] MPS Comm Alarm

[Brian Eng]

The change Nick suggested is not even few minutes of work to actually implement it, a bit longer to test it.

In theory that change can be done at anytime, but it's obviously much safer to do so when the magnet is at 0 amps. It would also be good to set the magnet to some low current (50A?) and make sure the comms reset doesn't actually try and set the current to zero.

Just to give a block of time, 30-60 minute should be more than adequate. It's easy enough to back out the changes if they don't work as expected. The bigger time sink is ramping the magnets down and back up.

________________________________
From: Probir Ghoshal <ghoshal at jlab.org>
Sent: Friday, August 7, 2020 1:27 PM
To: Nicholas Sandoval <sandoval at jlab.org>; Brian Eng <beng at jlab.org>; dsg-hallb magnets <dsg-hallb_magnets at jlab.org>
Cc: Eugene Pasyuk <pasyuk at jlab.org>; Ruben Fair <rfair at jlab.org>
Subject: Re: MPS Comm Alarm

Brian, Nick,

So how long will this take to carryout the work as suggested?
Eugene -  will there be a window/an opportunity to work on when the magnets are at 0 A?

Please let us know and we can plan out if that is going to be quick (Brian and Nick to suggest)
Regards

Probir
________________________________
From: Dsg-hallb_magnets <dsg-hallb_magnets-bounces at jlab.org> on behalf of Nicholas Sandoval <sandoval at jlab.org>
Sent: Friday, August 7, 2020 12:32 PM
To: Brian Eng <beng at jlab.org>; dsg-hallb magnets <dsg-hallb_magnets at jlab.org>
Subject: Re: [Dsg-hallb_magnets] MPS Comm Alarm

Hi Brian,

Thanks for this.  Yes it is definitely important to reset the MPS comms as soon as possible.  If the system tries to initiate a controlled ramp down while communication is lost the PLC will notice it is not progressing as it should and would initiate the MPS ramp down.  Once initiated we cannot recover until back to 0 amps again.

having looked at the MPS comm reset it is in the 'initialize' sub routine that we reset the current setpoint to 0 amps, we can easily comment out this portion at the next opportunity.

-Nick
________________________________
From: Dsg-hallb_magnets <dsg-hallb_magnets-bounces at jlab.org> on behalf of Brian Eng <beng at jlab.org>
Sent: Friday, August 7, 2020 11:25 AM
To: dsg-hallb magnets <dsg-hallb_magnets at jlab.org>
Subject: [Dsg-hallb_magnets] MPS Comm Alarm

Figured I'd post to the mailing list and get input rather than posting to the entries themselves; regarding the logentries related to this: https://logbooks.jlab.org/entry/3821968

If this particular alarm comes up again it probably would it be better to reset it as soon as possible?

While nothing is in danger we end up losing most of the software controls when the PLC can't talk with the power supply. Instead it's mostly hardware protection, fortunately during the last long break a lot of faults got moved to a slow dump in hardware, but best to not let it get that far.

The only reason I'd hesitate to make that the SOP is that is as Eugene noted it started to ramp down after resetting, which isn't very surprising. Any suggestions?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/dsg-hallb_magnets/attachments/20200807/41cdf660/attachment-0001.html>