Entry type: FAQ, Entry ID: 14782704, Entry date: 04/06/2009

How do you synchronize the date and time between an OP3 and an S7-200 CPU?

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There are two possibilities for synchronizing date/time between a S7-200 and the OP3:

The communication between the S7-200 and the OP3 is implemented within the interface area that has been entered in the ProTool project.

Fig. 1: Interface area

For time synchronization purposes, the areas control and response bits date and time are relevant.

Transfer date/time from the S7-200 to the OP3 

In the control and response bits area, bit 2 signalized the date/time request of the OP.

Fig. 2: Control/return information bits

The synchronization of the OP 3 with the SIMATIC S7 is carrie out in four steps:

  1. Every 15 minutes the OP 3 sets the bit 2 in the data byte n+0 on 1.
  2. If bit 2 is set, the CPU time has to be read with the function "READ_RTC" from the S7-200 and be copied into the date and time area of the interface area.
  3. As soon as the S7 program resets bit 2, the OP 3 recognizes that the S7 program has stored the current values for time and date in the interface area.
  4. The OP 3 reads out the recent data from data bytes n+15 to n+17 and n+21 to n+24 of the interface area.

Fig. 3: Time/date folder

Transfer date/time from the OP3 to the S7-200
If bit 6 of bytes n+0 of the control and response bit has been set, a new time was set on the OP. If bit 5 of Byte n+0 of the control and response bit is set, the date on the OP was changed. The new values for date and time are stored in the interface area of the date/time folder. For the S7-200, the values have to be copied back into the appropriate variable area and the setting for the CPU time have to be made with the funciton "SET_RTC". Bits 5 and 6 must be reset after setting the CPU clock.


  • Further information can be found in the manual of the OP3 under entry ID 1142799.

The STEP 7 Micro/WIN library as archive file:
Copy the "timeop3.zip" file into a separate directory and unpack the file. You can then integrate the library, which can be used in version V3.2.2.11 and higher of STEP 7 Micro/WIN, into your S7-200 project.

 Time_OP3.zip ( 2 KB )

Information on how to insert libraries in STEP 7 Micro/WIN is available in Entry ID 16689345.