IOC Guidelines¶

The EPICS IOCs used for control and monitoring in the NUSTAR DCS sub-systems should follow some general guidelines.

Guidelines¶

Standard records¶

The IOC database should contain a few standardised records

ioc:status record The status record provides a standard record to indicate that a certain IOC is active:

record(bi, "$(PREFIX):ioc:status") {
  field(DESC, "NUSTAR DCS status")
  field(ZNAM, "Not OK")
  field(ONAM, "OK")
  field(VAL, "1")
  field(PINI, "YES")
}

ioc:error record The error record provides a standard record for error/state messages. Other records in the IOC should use this record to communicate error and state conditions (29 characters maximum):
```
record(state, "$(PREFIX):ioc:error") {
  field(DESC, "NUSTAR DCS error message")
  field(VAL, "Undefined")
  field(PINI, "YES")
}
```
ioc:state record The state record is used in sub-system overview IOCs and provides a standard record that shows the state of the sub-system state machine (see also Sub-system State Machine):
```
record(state, "$(PREFIX):ioc:state") {
  field(DESC, "NUSTAR DCS state")
  field(VAL, "Undefined")
  field(PINI, "YES")
}
```

IOC Startup¶

IOC installed on single-purpose PC (only for one or more IOCs):
- IOC should start automatically at boot-up. This can be realised e.g. using an entry in the crontab
- IOC should be started in the background using procServ, on standard port 2222
IOC installed on a multi-purpose PC (also other functionality):
- IOC should be started from within a screen session

IOC Reboot¶

After a reboot of the IOC, the device should be in a safe and usable state. It should be fully controllable by only using Process Variables defined in the IOC.

If possible, the IOC should make use of the bumpless reboot feature offered via the autosave module. This allows for automatic restoration of the previously set values.