There's an extensive library of communication drivers that are supported by InTouch and System Platform, which can be found with the latest readme documents at the following link:
As a quick summary here is list supported: Allen Bradley (ABCIP, ABTC), Beckhoff (TWINCAT), GE (GESRTP), OMRON (OMRONFINS), Schneider Electric (MBTCP, SOMAC), and much more
