2.3 cawait

• description: cawait monitors one or more EPICS process variables and waits until user-specified conditions are met. Logical operations allow combining conditions, and optional commands or subprocesses may be invoked when events occur.
• examples: Wait for beam current to rise above 5 mA and echo a message:
  cawait -waitFor=SR:current,above=5 -onEvent="echo beam reached 5"

  Require two PVs to satisfy conditions simultaneously:

  cawait -waitFor=SR:state,equalTo=1 -and -waitFor=SR:mode,equalTo=2

• synopsis:
  usage: cawait [-interval=<seconds>] [-timeLimit=<seconds>] [-totalTimeLimit=<seconds>]  
   -waitFor=<PVname>[,lowerLimit=<value>,upperLimit=<value>][,equalTo=<value>][,sameAs=<string>]  
     [,above=<value>][,below=<value>][,changed][,monitor]  
   [{-and | -or | -not}]  
   [-repeat[=<number>]]  
   [-emit=event=<string>[,timeout=<string>][,end=<string>]]  
   [-preEvent=<command>]  
   [-onEvent=<command>]  
   [-postEvent=<command>]  
   [-onEnd=<command>]  
   [-subprocess=<command>[,event=<string>][,timeout=<string>][,end=<string>]]  
   [-pendIOTime=<seconds>]  
   [-noWarnings]  
   [-provider=\{ca|pva\}]

• switches:
  • -interval — seconds between checks (default 0.1 s).
  • -timeLimit — maximum time to wait for the condition.
  • -totalTimeLimit — maximum total runtime.
  • -waitFor — PV name and criterion for ending wait.
  • -and, -or, -not — logical operations on previous results.
  • -repeat — number of events to wait for (default 1; infinite if omitted).
  • -emit — emit strings for events, timeouts, or end-of-run.
  • -preEvent, -onEvent, -postEvent, -onEnd — commands to execute before, during, after events, or at end.
  • -subprocess — run a subprocess and send event/timeout/end messages.
  • -pendIOTime — time allowed for channel access operations (default 10 s).
  • -noWarnings — suppress timeout warnings.
  • -provider — choose channel access (ca) or PVAccess (pva) provider.
• author: Michael Borland, Robert Soliday, ANL/APS.