I am working as an internship on an Arduino based PLC. It is the M-Duino 58 Analog from IndustrialShields. I try to figure out how it works; Reverse Engineering. But i dont know why it has negative Digital Inputs like normal Digital Input I1.0 also has a connection -I1.0. It is probably a simple question but i cant figure it out. Hope you guys can help me.
I guess i figured it out. Seems to be the GND connections. Should read the Manual better next time.