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Author Topic: Is "GND" in the manual Common and +5v on the ZP5A-INT breakout board? (please!)  (Read 3399 times)

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Can anyone help me understand the Chinglish in the manual?

In terms of the inputs on the ZP5A-INT board one terminal (of a pair) is labelled as GND and the other is labelled with the pin number.  It seemed fine until I wanted to zero the tool - I had to swap the X, Y and Z plate leads from (whats labelled in the manual as) the pin terminal to the GND terminal for each of the inputs - which didn't make sense.  The 'pin' terminal appears to be at +5v relative to the GND terminal but I'm not sure if the board is holding it as such.  I think that my lack of understanding on what each of the terminals represents has meant that getting this far (with the zeroing and estop) has been more down to trial and error/luck and the auto-switch-set feature in Mach3!

I would find it easier if I there was a +5V, a GND and a lead to the parallel pin because I'd be able to install my own resistors and switches to allow me to make it active low/active high.  As it stands (and as the boards screwed down to the base) I'm struggling to understand what's going off.

I'd be really grateful if anyone could shed some light on this as I (hope and!) think this is my last hurdle before I can have a trial run.


Oh and just FYI the problem I'm having at the moment is a temperamental limit switch setup which seems to be either suffering from too high-a-resistance or noise, making the signal fluctuate giving Mach3 inaccurate readings (and not allowing me to set it up properly).  The problem is I can't begin to troubleshoot it until I'm more sure about how the boards working.  With nothing connected to a terminal I get 5v across the pin -> gnd terminals.  Is the pin held high by the BoB automatically maybe?

I appreciate any advice, however small, if it can shed any light on this for me!

Offline Tweakie.CNC

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It is not uncommon for a board to incorporate 'pull-ups' to +5V on all inputs. The limit / home / estop switches are usually 'n.c' and pull the input to GND so Mach3 is configured to have the used inputs configured as 'active high'. This way the used inputs are held at GND by the switches but when a switch is activated the input rises to +5V.

Hope this helps.

Hi Tweakie,  thanks for your reply - I've been trying to work out what the Mach3/BoB combination is doing because I can't fathom where the pin lies in the BoB circuit.  Mach3 seems to see the opposite of what I expect (i.e. it thinks an open NC switch is active low rather than the expected active high)... I've made another post because I wasn't sure it suited this subject heading which I hope to be OK.  I'd be grateful if you'd be willing to take a look to see what you think - it's a strange one (I can't work out whether the pin is connected on the GND or the PIN# side of the terminals!):