Long Post.... zene10 and lyonsden or anyone who has done this.
My understanding of how pinduino's (mine are WPC-Ext's) work on the electrical level in laymen terms is this.
The connectors, J126 for example are plugged into the pinduino and the pinduino among other thigs is plugged into J126 on the driver board.
The electronics (optoisolators) are looking for a pin on J126 to go high or low. The reason for the optos is it isolates the high voltage on the driver side and on the pinduino side of things through the arduino code get notified a pin is active or not. If this is correct then I ask the following....
If I run wiring from J126 or J127 or J130 as a pigtail off the main connector on the driver board and don't have to sandwich the adapter board, etc, I will still be getting the PIN state of the pigtailed connection if I terminate it to the connector on the pinduino.
In my example below I would run a pigtail from J130(7) (plunger on STTNG) to the connector on the arduino J126(3) as J126(3) is not used on STTNG, why loose the ability to monitor "something" else??
There are a few caveats... I still must code the nano sketch as if I am interrogating the state of a particular pin line on J126.
if (pd.pinState()->J126(3)) // Pin 3 is active //Plunger coil from J130(7) is active because I ran that wire.
Then do something
I don't see why this isn't possible especially since the 4 pin EXT aspect of the WPC ext uses addressing J126(14-17) which isn't real just an extension of the code to make things easier.
This way, by not moving the REAL J126 connector to the WPC-ext I can really run what I want to the the Pinduino and interrogate as I see fit....
If this is wrong please explain why it is. I don't want to blow up a pinduino if doing this will cause that to happen. I think I have read where these optos can handle even the high power coils at 50V.
The other reason I see this as a viable solution to maximize connections (STTNG only uses 7 of the 12 on that connector BTW) is that the connector doesn't have ground reference in the connector, that is handle by the driverboard completing the circuit which makes the coils fire.
Thanks for the long read. Does this make sense?