Log changes into cronologic event list (CEL)

Log changes into cronologic event list (CEL)

how is it possible to log changes of values into CEL when the value is not changed via
visualization but directly in the PLC, for example by hardware +/- switches.
This changes will normaly not logged into the CEL.
Currently I have solved this problem by a reaction matrix for the related variables.
This procedure works, but maybe there is an other way to solve this job?
Jürgen Berger

This is a migrated post! Originally posted on 13.03.2009 by user hicom. Please be aware that information can be outdated.