Profibus Communication failure
I am facing an issue with Profibus Communication. I am having 50 nodes in this loop with 2 repeaters. The first 7 nodes are CI801 slaves and rest of them are Siemens Sinamics VFD Drives. Master is CI854A attached to PM981.
The issue is that sometimes (randomly) there is some fault in network and some of these VFDs stop communicating with Master. But CI801 modules continue to communicate. After that, I had to reset the VFD from its panel then it starts communicating again.
I have done basic testing of terminations, addresses, short circuits, transmission speed (1.5Mbps), signal strength, physical wiring of A-B wires. Everything is fine only. I tried to analyse the loop with Probibus analyzer but it showed that signal strength and healthiness perfect.
I am not sure what may be the problem behind VFDs getting out of communication. Is it problem concerned with VFDs or Profibus loop? Because CI801 modules continue to communicate even if VFDs don't.
Please Comment !!!