Well you just connect the ethernet connecter to a switch connected to the 800xA system and then you wait until we find our crystal ball to figger out which version 800xA version you have, which controllers you have connected to 800xA, what your ultimate goals are, which things we have to consider to give you a proper answer. But my crystal bal is been missing for a while, but maybe the other forum members have there's ready for service.
if you want a useless answer, your question is fine. If instead, as I think, you are looking for help, I think you should be a little more explicit in your request and ask a question with all the information about your application, it being understood that those who can and want to answer, having time, will do so. Also because, fortunately, you do not pay for the words used in presenting a question .... As for me, since I don't know the AC800 series, I can only give you some advice on AC500, if you want to clarify what you want to do.