TuxEIP is a communications library that facilitates communications to Allen Bradley Controllers, using it, a programmer can write programs to Read/Write controller/program scoped tag data in the following PLC : ControlLogix, PLC5, SLC500, Micrologix, FlexLogix (and probably much more, but that's all i have tested).
These PLC are reachable using Ethernet, ControlNet, DH+.
As this library implement misc functions to interact with objects defines by the CIP protocol (Connection Manager, Message router...), you can easily add your own function to act on such devices.