We have HIMA H-51 PLC with a DOS based PC used as a MMI. We have the PLESY P software running in this MMI. This software is responsible for alarm logging & recording sequence of events with millisecond timing.We are in the process of synchronising the time of this recorder with the DCS. We would be using a Global clock for the same. What time does the Plesy P software take? Is it the PC time of the PLC processor time? We can implement the global clock after confirmation on this query.

 

Hi
Plesy-p standardly use PC time and set time in CPU. Plesy can read time from some drivers,
for example PC31 etc,.

 

The master time can be taken from the PC or the PLC. This is configured within PLESY-P. Optionally a realtime clock building block could be added to the PES to enable the DCS to synch the time by either setting it to a predetermined time once each day e.g. 12:00am, or by writing to time and date registers then sending a synch bit over MODBUS if available.