Parameters > Citect.ini File Parameters > IOServer Parameters > [IOServer]AlwaysCallStopUnit


Determines whether CitectSCADA attempts to call the StopUnit function for a driver when the unit goes offline so as to release resources allocated for an I/O Device..

The StopUnit call releases resources allocated for a PLC. Under normal circumstances, this occurs when the PLC is online at shutdown, or disabled. Since the unit may not get a StopUnit when it is offline at shutdown, its resources may not have been released and CitectSCADA crashes can occur.

By default this parameter is set to 1 and commands that a StopUnit is called. This may prevent crashes at shutdown. Usually if setting AlwaysCallStopUnit, you would set AlwaysCallStopChannel.

Allowable Values:

Default Value:1

See Also