I came across this ControlLogixNET, it is an open source project that claims to "interface with Allen-Bradley ControlLogix, CompactLogix, and MicroLogix PLC's" and "also tested to work on Mono!!!!".
Other than that, there is not much of info on how to and a lot of unanswered questions.
Anyway, since it is depends on EIPNET, I downloaded EIPNET and compiled it to get EIPNET.dll.
Next re-add references ( EIPNET, ICommon) in ControlLogixNet project, build it.
Next re-add references( EIPNET, ICommon,ControlLogixNET)in all projects of the Examples folder, build it.
Next , change the Startup solution to a project like SimpleOperations.
Change IP address and path to match, in my case it's a compactlogix so path is just 0.
Run it and read a tag.