profibus DP comm.problem

We have two profibus loop connected to S7-400 plc. Sometimes communication of the loop disconnects for a second and comes back. Because of this all the motors stoppes. On the hardware diagnose it always shows several DP slave station failure. That' why we don't know exactly where is the problem. An example of the failure is as below:
DP master system ID:3
DP slave input address:16291
Base address of DP master:16372
OB number:86
DP slave station number:100
External error, incoming event

Anybody advice anything how can we find where the problem is wellcome.
Thanks ...
apesky

I had a similar problem with a profibus network. My problem was with some of the terminations on the cables, and some of the jumpers on the connectors. Check those first.

This fixed my problem, I hope it fixes your too.

How many slaves are connected? Are the slave failures random? If several fail, check the connection between the last "good" node and the first failed one.

I agree, this sounds like a connection problem to me. I'm guessing that one of the wires isn't inserted far enough into one of the connectors.

Also, you didn't mention how long the profibus runs are. If it is a long run, maybe you are right at the point where a repeater may be beneficial.

I have found particularly with Eurotherm drives that if a problem exists on their profibus, the subsequent connections also appear faulty.

Possibly there is a fault device in your network? After you have checked all the connections etc and if it still doesn't work, go to the slave closest to the master (cable wise) that has a fault and thouroughly check it.