If synchronization procedure is not performed , the safety I/O can enter their safe or fallback state after the clock drifts for about a communication delay timeout.

NOTE:
If we are installing safety I/O modules in an RIO drop, enable the NTP service and configure the safety CPU as either an NTP server, or as an NTP client (with another system device configured as the NTP server). If one of these two designs is not implemented, the time settings of the safety I/O modules and CPU will not be synchronized and black channel communication will not operate properly.
If we are installing safety I/O modules on local rack (or in an extension of the local rack), it is not required to enable the NTP service.

Released for: Schneider Electric India