If You are Shutting Down the Run Control

Follow these instructions first to try to "gracefully" shut down the CRT. This prevents leaving the hardware in a potentially inconsistent state.

  1. Shut down every other component you can normally.
  2. Click on the Process Manager node in the list-tree on the left side of the main Run Control window. Click Force SHUTDOWN. Among other things, this really just calls a script that shuts down the CRT backend gracefully. Force SHUTDOWN shouldn't take more than a minute or two, so move on if it takes too long.
  3. If that didn't work, the Run Control's Finite State Machine might be "confused". Go to the next section.

If You Tried to Boot from Run Control or Otherwise Got Stuck

These instructions could put the CRT hardware into a weird state that might eventually cause problems.

  1. You have to LogInToCRTServer to follow these instructions
  2. Look for running processes named "readout":

    ps -u np04daq
  3. Let the CrtExperts know via Slack that you are about to kill the CRT backend. Then, kill all of np04daq's processes named readout on the CRT server:

    killall readout

    If the Run Control was hung, it should now be free. Otherwise, the Run Control's Finite State Machine might be confused, so contact a DAQ expert for help.

Why this Happens

The CRT board reader really just reads files produced by the CRT backend process. This backend process, called "readout", is started once for each USB stream plus one extra process (I'm not yet sure why). A particular CRT board reader, usually crt0, is responsible for starting and stopping the backend. If crt0 stops "abnormally", which can happen even in normal shutdown transitions, this backend process can be left running so that it blocks the port over which the Run Control communicates with the CRT board readers.

-- Main.anolivie - 2018-11-02

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Topic revision: r3 - 2019-03-15 - AndrewPaulOlivier
 
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