Hi experts

                  I do have 3 VFD and 6 Control Valves on a y-coupler. The first VFD communication fails after every 10/15 min.

So can anybody advise me what needs to be check for this?

Thanks in Advance.

Hi, 

It can be many things. We need to known how is your system installed, configured. Installation drawings could help a lot. Also  screenshot of your HW config. 

Profitrace could be a big help to diagnose the profibus nodes, Amprolyzer is an other option.

You could check the obvious things first like: shields, plugs, end resistors, DP slave, power supply etc...