MMS Failure and Time Synchronisation
1.Will MMS communication between safety controllers fail if the controllers are not time synched ?
2. If the answer to item 1 is yes , then will both analog and boolean MMS data transfer stop / fail or get affected by no time synch between safety controllers ?
3. What is maximum time drift allowed between safety controllers for MMS to keep working ? Please give reference to 800xA manual for any max time drift values stated.
I'm no pro on the Control IT product suite, but AFAIK:
1. Yes (error code on communication block will tell if this is the case)
2. Yes (error code on communication block will tell if this is the case)
3. Don't know maximum allowed drift. Use CNCP or SNTP protocols for higher precision.
MMS Time Sync protocol is ancient and kept for backwards compatibility with older PLCs. AC 800M support MMS when CS Time Set enabled is "ON", but recommendation is to set it to "OFF" and use CNCP or SNTP which are modern and offers far better precision.