I am starting an upgrade process for all my SLC50* PLCs and working out the communication of my machines for the upgrade. I ran into this complication I don't understand. I have 2 machines that work together using 1 HMI. Both machines have their own PLCs. Both are running SLC5/02 to 1747-AIC link coupler then to the 2711P-RN6 interface with the DH-485 communications running parallel. I don't understand how this works, or how I might possibly upgrade the communications from 2 PLC's into 1 HMI without linking the PLC's programming first. (Also, a complication I am working on, I only have the Runtime file, not the ME file for the HMI program).
