Hi,
I've got a bit of a puzzle that I've spent a few days on and can't for the life of me solve... I can't work out wither the Parallel Pin is connected to the GND side or the PIN# side of the BoB for any particular pin - it seems to be connected to both (sort of). Here's what I mean:
I've got the zeroing on my machine working. I've wired the XYZ homing-plates into the GND terminals on the BoB for each pin. I use a common wire for the crocodile clip (that attaches to the cutter) that goes to the PIN# terminal of Z. It works...
However I was under the impression the PIN# terminal (which is at +5V relative to connection marked GND making me believe it's held high) should also work - i.e. the reverse of the above, but it doesn't. Mach3 seems to auto-set the pin numbers correctly and sets them as active high (I think the ZP5A BoB might be inverting the signals?) but when I run the same auto zero code it doesn't work.
I just can't understand what is happening - whether the Pin is held high (and is connected to the terminal connection marked PIN#) or whether the Pin is held to ground and is actually connected to the GND terminal. Because Mach3 auto-sets the same either way, but just doesn't work via the auto-zero command I'm well and truly at a loss!
I've attached a (badly drawn!) diagram in the hope this helps me explain! (The G is GND and the P is the appropriate PIN# terminal at +5VDC relative to the GND)
Oh, and I also understand the theory behind active low/high for both NC and NO but with this BoB Mach3 doesn't set as the theory suggests. For example the Estop is connected NC directly through the PIN# and GND terminals of a pin but when the switch is opened Mach3 see's it as active low. I was of the belief that it should be active high (so the pin is held low whilst switch is closed and then goes high when the switch is opened).