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Message ID: 14745     Entry time: Wed Jul 10 16:53:22 2019
Author: gautam 
Type: Update 
Category: SUS 
Subject: PRM watchdog condition modified 

[koji, gautam]

We noticed that the PRM watchdog was tripping frequently. This is a period of enhanced seismic activity. The reason PRM in particular trips often is because the SIDE OSEM has 5x increased transimpedance. We implemented a workaround by modifying the watchdog tripping condition to scale the SD channel RMS by a factor of 0.2 (relative to the UL and LL channels). We restarted the modbus process on c1susaux and tested that the new logic works. Here is the relevant snippet of code:

# Disable fast DAC if variation tests too high
# PRM Side is special, see elog 14745
record(calc,"C1:SUS-PRM_LOGIC")
{
    field(DESC,"Tests whether RMS too high")
    field(SCAN,"1 second")
    field(PHAS,"1")
    field(PREC,"0")
    field(HOPR,"1")
        field(LOPR,"0")
        field(CALC,"(A<B)&(C<B)&(0.2*D<B)")
        field(INPA,"C1:SUS-PRM_ULPD_VAR  NPP  NMS")
        field(INPB,"C1:SUS-PRM_PD_MAX_VAR  NPP  NMS")
        field(INPC,"C1:SUS-PRM_LLPD_VAR  NPP  NMS")
        field(INPD,"C1:SUS-PRM_SDPD_VAR  NPP  NMS")
}

The db file has a note about this as well so that future debuggers aren't mystified by a factor of 0.2.

ELOG V3.1.3-