A direct link would probably be best, so I'd seriously look at cardosocea's links.
If that proves unworkable for some reason, and you have an HMI on the system, the HMI *may* be able to serve as a gateway device. I've done it with Red Lion HMIs easily and with older Siemens MP series HMIs with more difficulty. I'd expect their newer HMIs to work as well, but I never tested it. Like I said, I'd prefer a direct connection, but the HMI may be another option.