Profibus communication failure in S7 PLC

[arocon]

One remote DP interface (IM 151-1) module of S7 PLC system going to stop suddenly. It is the farthest end.That module is supplied by a power supply which supply other remote DP interface modules. Whenever fail happen we turn off and on power supply of that interface module and it work fine. We measure power supply in failure module and found 23.6 Volt instead of 24 V. Could anyone explain me what could be reason for the failure of the interface module ? Or what need be checked.

Thanks.

 

[JesperMP]

Try to replace the interface module.

 

[ojz0r]

Either its what Jesper said or it might be the cable (without further diagnostics you cant know).
Check the profibus connections