Data persistence

Persistent data retain their values when the PLC project is reloaded. The values of persistent data can be restored after an uncontrolled termination (power failure), a download or a cold start.

The RETAIN variables provide another means to keep data remanent. Like PERSISTENT variables, RETAIN variables retain their values during an uncontrolled termination (power failure), but not during a cold start or when the PLC project is downloaded again, in which case only the persistent data 'survive'.

See also:

Resetting the PLC project
Reference Programming: Remanent variables - PERSISTENT, RETAIN