Introduction:
The Cavity Summary Display is similar to the Klystron displays used in LCLS and FACET, but instead of displaying klystron information, the Cavity Summary Display shows cavity faults for all cavities in cryomodules 01 - 35. The GUI also displays whether a cavity's SSA is on and whether or not is has RF.
How to Launch the GUI:
To launch the Cavity Summary Display locally at an OPI, follow the instructions below:
- Open a terminal
- Type in set_profile srf
- Type srfhome. This will launch a PyDM version of SRF Home
- Click "Cavity Summary GUI." This is a PyDM GUI and typically takes 2-3 minutes to launch, so be patient!
Alternatively, you can use Launchpad to open the GUI by typing in "SC Cavity Summary Display."
Interpreting Information on the GUI:
Cavity Shapes and Colors:
Now that we've launched the GUI, we want to use it to help us troubleshoot and keep an eye on the cavities. The GUI is broken up into the four linac regions (L0B, L1B, L2B, and L3B) each with their own cryomodules (abbreviated as CM). Each of these cryomodules has 8 cavities. If a cavity is faulted, it will display a Three Letter Code (TLC) instead of its cavity number.
The different cavity statuses are as follows:
- Green diamond with cavity number - This indicates that the cavity is healthy and has no faults.
- Yellow triangle with TLC - Cavity has a minor fault.
- Red hexagon with TLC - Cavity has a major fault.
- Gray octagon with TLC - Indicates cavity hardware mode (maintenance, maintenance done, or ready)
- Transparent octagon with 'OFF' TLC - Cavity hardware mode has been set to Offline
- Purple circle with TLC - The fault PV associated with the cavity is disconnected.
The different shapes used for these faults were chosen with the purpose of making the GUI red/green color blind accessible.
Cavity Status Bars:
Below each cavity are two status bars. The left status bar indicates whether the SSA is On or Off, while the right status bar indicates whether the RF is On or Off.
Understanding Cavity Faults
Three Letter Code (TLC) Decoder:
As mentioned earlier, a faulted cavity will appear on the GUI as a red hexagon with a three letter code (TLC). To figure out what fault the TLC corresponds to, we can click on the "Three Letter Codes" button in the upper right corner of the Cavity Display GUI. This will launch a Cavity Fault Three Letter Codes panel with an alphabetized list of all the potential cavity faults as well as a short description of what each fault means.
Cavity Faults Panel:
Although cavities may have multiple faults at one time, the display can only show one fault at a time and it is designed to show the highest priority fault (aka the most severe/concerning fault) first. To see what other faults may be affecting a cavity, we can open a a cavity's fault panel. To do this, we first click on a CM number directly from the Cavity Display. From there, we'll get a panel with a list of cavities. Click on the cavity number to open its fault panel.
As mentioned above, the cavity fault panel lists faults in order of decreasing priority. To see the PV associated with each fault, we can middle click the fault status box (which will display "OK", "FAULTED", or "INVALID").
GUI Backend
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 then clicking "Stop Backend" followed by "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 occasionlly 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).