I’m still working on it. The plan is to create a box that goes between sprayer and mueller, in this box there will be the controller connected to AOG (could be USB, UDP, WiFi, …) and relays. Section signal will be read from mueller and output section signal will be coming from a relay board. Controller will read section status from mueller box and it will manage the relay according to AOG (Manual/Auto). So no new switch needed except for switching Auto/Manual.
Note also that from this box there will be a cable going to another small box which fits between the 2 mueller box. The reason is that section signal must be sent to the top mueller box (spray control) so that it can calculate the rate. It needs to know the section status from the relay (when spraying in Auto mode).
So with this setup, you can just unplug the 2 boxes and switch back to original mueller system!
I ordered a lot of components (optocoupler board, ESP32, relay board, connectors harting to connect between mueller boxes, din 41622 connectors to connect between mueller and sprayer, wires, …) and last ones should be delivered…today ! So I expect moving forward on this in the coming weeks. Hopefully I can spray using AOG this spring 