ISIS PV Guide - ISISComputingGroup/ibex_developers_manual GitHub Wiki

Wiki > The Backend System > IOCs > ISIS PV Guide

This does not cover the PV naming convention, rather it covers the PVs you need to implement.

The PV naming conventions are described on the PV naming page.

1. For a slow changing value (e.g. a temperature), there needs to be a current value readback, a setpoint and a setpoint readback:

   record(ai, "$(P)TEMP") 
   {
       field(SCAN, "1 second")
       field(DTYP, "stream")
       field(INP,  "@devEuro.proto getCurrentTemp $(PORT)")
       field(PREC, "3")
       field(EGU,  "K")
   }
   
   record(ao, "$(P)TEMP:SP") 
   {
       field(DTYP, "stream")
       field(OUT,  "@devEuro.proto setTempSetpoint $(PORT)")
       field(PREC, "3")
       field(EGU, "K") 
   }
   
   record(ai, "$(P)TEMP:SP:RBV") 
   {
       field(SCAN, "1 second")
       field(DTYP, "stream")
       field(INP,  "@devEuro.proto getTempSetpoint $(PORT)")
       field(PREC, "3")
       field(EGU,  "K")
   }
   

2. For a value that changes instantly (e.g. a trigger level), there needs to be a current value readback, a setpoint and a setpoint readback. However the setpoint readback should be an alias for the readback:

   record(ai, "$(P)TRIG_LVL") 
   {
       field(SCAN, "1 second")
       field(DTYP, "stream")
       field(INP,  "@devHameg_8123.proto getTriggerLevel $(PORT)")
       field(PREC, "3")
       field(EGU,  "V")
   }
   
   record(ao, "$(P:)TRIG_LVL:SP") 
   {
       field(DTYP, "stream")
       field(OUT,  "@devHameg_8123.proto setTriggerLevel $(PORT)")
       field(PREC, "3")
       field(EGU, "V") 
   }
       
   alias("$(P)TRIG_LVL", "$(P)TRIG_LVL:SP:RBV")
   

3. For a toggle-style button (e.g. voltage on/off) where the current setting can be read, use the same format as 2) but with binary records:

   record(bi, "$(P)VOLTAGE_ON") 
   {
       field(SCAN, "1 second")
       field(DTYP, "stream")
       field(INP,  "@devPSU.proto getVoltageOn $(PORT)")
       field(ZNAM, "OFF")
       field(ONAM, "ON")
   }
   
   record(bo, "$(P)VOLTAGE_ON:SP") 
   {
       field(DTYP, "stream")
       field(OUT,  "@devPSU.proto setVoltageOn $(PORT)")
       field(ZNAM, "OFF")
       field(ONAM, "ON")
   }
   
   alias("$(P)VOLTAGE_ON", "$(P)VOLTAGE_ON:SP:RBV")
   

4. For a toggle-style button where the current setting cannot be read or a push-style button (e.g. a reset button), there needs to be a setpoint and, for convenience, an alias for the current value. This allows the value to be set using either PV.

   record(bo, "$(P)RESET:SP") 
   {
       field(DTYP, "stream")
       field(OUT,  "@devMyDevice.proto reset $(PORT)")
       field(ZNAM, "YES")
       field(ONAM, "TRUE")
   }
       
   alias("$(P)RESET:SP", "$(P)RESET") 
   

5. A read-only value (e.g. a status string).

   record(stringin, "$(P)STATUS") 
   {
       field(DTYP, "stream")
       field(INP,  "@devMyDevice.proto getStatus $(PORT)")
       field(SCAN, "1 second")
   }
   

6. For a value(s) which the user wants to review before changing then press a set button (for motor records this can be done via SPMG):

   • XXX - read back
   • XXX:SP - set the value immediately
   • XXX:SP:RBV - the value that the device has as a setpoint
   • XXX:SP_NO_ACTION - don't set the value but wait (this is a temporary value if you restart the IOC it is lost, consider putting autosave on it)
   • XXX:ACTION - when written to with any value take the SP_NO_MOVE and send it to the device
   • XXX:ACTION:SP - when written to with any value take the SP_NO_MOVE and send it to the device
   • XXX:CHANGED - are the setpoint on device and current setpoint different? It is an enum:
     • NO there is no change to apply
     • YES there is a change to apply