The proprietary DCS is using a proprietary protocol (over TCP/IP) to communicate amongst its Controllers. It can also communicate via ModBus, but only "under-the-hood" to I/O Controllers. In other words, that protocol is not "available" or "exposed to" the application programming environment. It is essentially "hard-coded" at a lower, hidden level.
But - like I said ... we have a Wonderware front-end that is talking to this OPC interface on the proprietary system, sending data bi-directionally, so (in theory) almost anything should work, right? OPC is supposed to be a layer that presents a protocol that other OPC-compliant software can talk to, right?
But OK - it sounds like Kepware is the way to go.
So if I install the OPC interface for the proprietary DCS on an existing Server sitting on the Process Network, then I would also install the Kepware OPC Client on this same machine (??), and then the "Kepware AB" software on the other Server which has connectivity to the subsystem (and PLC) I am trying to link to???
Is that right ... 3 pieces of software?