CPU 1516-3 PN/DP, TIA V17, six ET 200SP stations in a line. Last week we put a SCALANCE XB208 between the CPU's port 1 and the first station so a second Comfort panel could go close to the machine.
Everything runs. All six stations green, both panels online, no station failures. But since the switch went in, the MAINT LED on the CPU is yellow and won't clear, and the buffer says "Maintenance required. Neighbour mismatch, port 1. Configured partner: io-st1 port 1" or words to that effect. We put new patch cables on both sides of the switch, power cycled the CPU and the switch and downloaded the hardware again, and it comes back every time.
Is this the switch, or is a yellow MAINT LED just cosmetic? Not sure how hard to chase it. Could someone explain what the CPU is comparing when it says the neighbour on port 1 is the wrong one?
Did the integrator draw the port to port topology in the project, the topology view with lines between the ports? If he did, the CPU checks its neighbours over LLDP, and it might be seeing a switch where it expects io-st1.