Hello Jon,
Yes, I believe the example you are looking for is this one:
The .zip file linked in the above topic has a C example. As far as reading and writing variable tags, that cannot be done via DMCP. You would need to define your variable tags with RMCTools software and flash the controller’s non-volatile memory, but once the variables have been defined then you can read and write to them directly.
For details on formatting DMCP packets, see:
Communicating Directly via TCP
Communicating Directly via UDP