Idle time is the spare time of a DCS CPU, it means that the DCS CPU has finished scanning its I/O state, program executions, and updates the I/Os, for example a DCS has 60 secs Idle Time and the total time that the CPU has finished scanning
and updating the I/O is 15 secs that means the that CPU of the DCS has 45secs left in his time or known as the Idle time.
Im sure you can understand what is it's significance.
It is significant if it goes down to zero!
Alarms are processed in idle time - so if you're having problems with alarms - and you have very little idle time you have problems.
