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The Cavity Display GUI has a watcher status in the upper left hand corner to communicate whether the backend code is running. For a little background on how our watcher works: the backend code has an incrementing PV (PHYS:SYS0:1:SC_CAV_FAULT_HEARTBEAT) that will continuously update as long as the backend code is running. If this incrementing PV stops incrementing, then the watcher PV (ALRM:SYS0:SC_CAV_FAULT:ALHBERR) watching it will change its status from "RUNNING" to "NOT RUNNING."
If you notice the watcher status indicates "NOT RUNNING", feel free to restart the watcher by launching an SRF Home via Launchpad and clicking "Start Backend." After a minute or two, the backend should be working again. There is a known bug specifically with the cavity display GUI on the Large Monitor where the display occasionally freezes. If the GUI works locally on an OPI but is frozen only on the Large Monitor, the Large Monitor GUI might just need to resized ever so slightly to wake it up (this is a very weird and particular bug that occurs only on the Large Monitors).
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