Extruder line. ControlLogix 1756-L61 with a 1756-CNB in slot 2, ControlNet to three 1794-ACN15 Flex racks and two PowerFlex 700 with the CNet card. RSLogix 5000 v20, RSNetWorx for ControlNet whatever came with it, 2012 vintage.

CNB died Friday, OK LED red, no comms. Put in the spare from the shelf, node switches to 01 like the old one, powered up. CNB is green now but every rack under it has the yellow triangle, 16#0204 or 16#0203 depending on which one you click. The drives too.

Went online with RSNetWorx and it complains about the keeper. Something like signature mismatch, and the network status has a red X. I have not scheduled a ControlNet network since the original commissioning, that was a contractor.

Tried: power cycled the whole chassis, checked the node switches again, both rotaries, same. Swapped the tap on the CNB with a known good one.

Is the spare CNB bad, or does it need something loaded into it? The DeviceNet crowd would just set an address and go.