I am trying to understand the schematics for the GA Industries Pump Director 7600 (pages 9-11).
As far as I can tell, this unit operates completely on 120VAC. Why then are they using diodes with the relay coils? Is the supply being rectified somewhere that I'm missing?
My overarching goal is to figure out where I can tap into the circuit to get an indicator of the HOA switch position (shown on page 9 bottom right, and page 10 bottom middle). I need some sort of output which is energized when the HOA switch is in the Auto position and not energized in the Off position, which my PLC can then read. Note that my PLC can accept 120VAC and 24VDC inputs. I'm also open to using a relay to isolate/convert the signal if that could work.