Currently looking at getting a S7-1200 talking to ignition over MQTT. Would be interested in hearing if anyone else has gone down this path already and any issues they had. Don’t have the hardware yet so I can’t do any testing of my own.
I realize this is not an answer to your question, but I thought you should be aware of other options.
Maple Systems makes a MQTT / OPC-UA / Modbus gateway that is very affordable and super easy to use. What makes to product so sweet is that it uses the Sparkplug B (Cirrus Link) protocol. So if your using the Cirrus Link MQTT Modules with Ignition it’s a plug and play type of setup.
I just wanted you to know, it you are not interested just dismiss this reply!!