Im working in big project too. My goal is to have an OSPi and 11 extension boards. Each extension board is 50 m from each other, with an distance of 550 m
I allready tested at the midle of the distance and i noticed that i have signal to extension boards but is not enought to turn on the valves.
With the FTP cable that i use to connect each extension board i use 2.5 mm power cable for 24V AC.
This power came from the same power supply.
So if i connect the 3x GND from FTP cable to GND at 2.5 mm power cable (24V AC), in this way the valves work fine. Tested with 1x extension board at 300 m from OSPi.
But now i having some trouble, when i try to connect the 5x extension board there is no answer from OSPi.
My question: using the interval program is there any limitation of extension boards? We need to change the code?