Hi again 
Yes, that will work. The main change is the PLC is becoming a Ziti client too, like the HMI, but for a different Ziti service.
You can use a router sidecar for the PLC to provide both functions:
- host.v1 for PLC SIEMENS with a target address like 127.0.0.1:102 (TCP)
- intercept.v1 for the PLC OMRON
This means the PLC SIEMENS node will need only the router sidecar for both Ziti services and functions as a server-side host for one and client-side dialer for the other.
I shared a live collaboration diagram link with you in a private message. Will you see if it makes sense and edit at will to reflect your aim?
- link to previous topic where we sketched out the first version of this: Using Ziti to "make Zero Trust something that is not, without touching it" - #40 by qrkourier