AC 800M communication problem - Profibus
We have AC800M(PM861) ABB PLC System, but presently we are facing problem with frequent profibus commmunication make & break. This controller is connected with 07 Nos. nodes. But during trouble from node -3 to node-7 communication may got disturb & frequent profibus communication make & break problem occurs with in friction of second. Controller got automatically connected with all node for some time being & for some time being its communication may disturb & node showing error slave does not exist.
We have CI801 communication module with PM861 redundent controller.
Presently we have replaced profibus connector & cable from node-2 to node-6. but still the problem can't resolved yet & during communication problem from node-3 to node 7 communication got break for time being, but after friction of a second it automatically got connected
The phenomenon is very erratic, Pls help
It sounds like EM reflections from the end of line back towards the first node.
Try to change the first and the last profibus connector..
Any new frequency converters installed close to Profibus cable?
Check whether shielding is connected properly each other of incoming and outgoing cable in each PB connector.
Without any tracer it will be little difficult.
If any tracer there, then try to check Signal voltage and noise levels and signal behaviour.
It will helps to solve problem.
See the status of module in Control builder.
If it shows connection down, then try to reroute profibus cable from node - 3 to node-7 in trial mode. Also check for shielding in all profibus connectors.
Also check wheather cable laid along with power cable ?