DiscreteDevice object runtime behavior

Startup

All statistics are reset.

Going onscan

• If the PVMode is set to Manual, then the PV is the last value, and the quality is UNCERTAIN.

• If the PVMode is set to Auto, then the PV is the Fault state, and the quality is INITIALIZING.

• PVAuto is set to the Fault value, and the quality is INITIALIZING.

• The time stamps for PVAuto, PV, and other calculated attributes are updated to the current time if their value or quality changes because of a scan state change.

Running onscan

See About continuous execution.

Going offscan

• If the PVMode is set to Manual, then the PV is the last value, and the quality is UNCERTAIN.

• If the PVMode is set to Auto, then the PV is the Fault state, and the quality is BAD.

• PVAuto is set to BAD quality, Fault value.

• All alarm conditions become false and input values go to BAD quality.

• Any command timeout alarm timer that is pending is reset.

• The time stamps for PVAuto, PV, and other calculated attributes are updated to the current time if their value or quality changes because of a scan state change.

Offscan

The object is passive.

Shutdown

If a reference to PV was registered and suspended at startup, that reference is activated and unregistered.