Synchronizing Magelis STU Time with Modicon PLC


Thread Starter


Hi Experts

Novice to Modbus and need to synchronize terminal clock with a Modicon m241 PLC.

I have setup a Modbus driver in my HMI and set up my plc as a Modbus client. Modbus communications seems okay but unsure how to setup the terminal dialogue table to read the rtc from the plc.

Any tips or pointers to information would be much appreciated as this procedure doesn't seem to be very well documented.

Kind regards.
Time in the Magelis is in integer format. Time in the PLC is in IEC time format. So not exactly compatible.

I have done time sync many times and have a working solution. At my client, we link four HMIs to the PLC clock.

Sync is within a second between all.

Post your email and I will send you the info.
Hi Brian

Thanks for the reply, I am able to display/read the time and date using a numeric display which reads the variables from the SYSTIMEDATE block on the plc, and I can also write to it from the HMI. I am unsure on how to map to the Modbus register and as you say also which format the data has to be presented. The Variables within the SYSTIMEDATE Block are Dint.

My Email is [email protected]

Kind Regards.