OK, I'll give it a try...
You have your hardware in front of you and a lot of information we don't have.
By your 3rd message you finally mentioned that it is a SLC 5/04. Thre are at least four different networks available on SLC processors. The SLC 5/04 usually communicates via DH+. The ControlLogix is also on the DH+? Using a 1756-DHRIO card maybe? Or you could have an ethernet converter on the serial port of the SLC 5/04, we don't know.
Basically, your question is too general for a reasonable answer. No one is going to take the time to write an answer to every possible configuration. Besides, that's available in the manual. If you want an answer tailored to your problem, do a better job describing the problem.
At this point, the answer is still very general. You can probably use a message.
Good luck