Alarm F01625 Sign-of-Life error in safety data Sinamics S120

Dear Expert

In our factory using  Sinamics S120 with CU320 and 4 units MoMo using Dfrive CLIQ  cable  for communication from CU to all MoMo.
At the normal, running CU often trip with Alarm F01625 Sign-of-Life error in safety data. Then we reset the drive by the power off and on again.
Then we try to do some action as directed on remedy, even  we replace  with a new CU. But the alarm still appear.

Are any somebody have the same experience with me, please  share the solution ?
Is there another solution need to do to solve my problem?

Regards

Hello, I am getting the same alarm. I have seen the alarm on two different CU's now. Also, it has occurred on two different MM on the same CU. i have replaced all drive cliq cables between the MM and CU, but i am still not convinced this will solve the problem. The link provided did not lead to any information on this alarm. 

Please help