Quick Data Comms to AB PLC

One of my readers was asking for a quick way to talk via Ethernet to a Rockwell AB PLC.

You can actually talk to a ControlLogix by only understanding TWO (2) different packets, each with a response, so four packets I guess. The problem is this uses "UCMM" style communications, which the PLC has very limited resources for. Said another way, the CIP Connected Messaging or I/O production both include an inherent allocation of resources, while the UCMM is designed to be used ONLY to setup such pre-allocated resources.

So yes, you can use the information below to create a literal quick-n-dirty solution, and if you talk more than a few times a second you might start to interfer with other communications to the PLC (which is not a good thing!) However you could treat this as a proof of concept, and then work to do the communications more fully per the ODVA specs.

Here is the PDF of how to read/write to the PCCC Object in a Logix Processor here.