I've searched for this info but have found next to nothing. The documentation of the CNC4PC c25 board says the way to wire up a probe for auto zero is to run an input wire to the bob on pins 10-13, 15 and run a 4.7k ohm res. from 5vdc pin to that input pin, and to run a wire to a bob grnd pin. What I've done is run an input wire to port1, pin15, bridged the 5vdc pin (between pins 12-13) and pin15 with a 4.7k ohm res. and run a wire to the bob grnd pin(between pin 15-16). In Mach3 in the pins and ports dialogue I've enabled the probe, set the port to 1 and the pin to 15 and left the active low and emulated to the default, which I think means it's set to active high? When I short the probe wires there is no indication that the probe is active....so what did I do wrong? I'm running the 2010 screen set, Mach3 3.043.062, and ESS v10r2d1d plugin.
Take 2:
When in the ESS Data Monitoring utility there is no response on pin 15 (in the data monitoring utility) when I short the lead from pin 15 to board GND. The homing sensors are working as expected, pins 11-13 are checked in the data monitoring utility when the sensors are triggered and unchecked when not triggered.When I put a voltmeter from GND to pin 15 (bridged to 5v through a 4.7k ohm resistor) it reads .49v and when I short the lead from pin 15 to GND the voltmeter drops to 0v...this is the expected result, right? The only thing wrong, in my uneducated guess, is that I'm not getting 5v untriggered, is this correct? This being the case, activation would not show up in the data monitoring utility because it is looking for a 5v input, correct? I'm not an electronics expert or even a newbie so I'm guessing here, is the 4.7k ohm resistor from the 5v pin( between pin 13 and 14) and pin 15 the correct resistance? How would or do I get 5v to pin 15? Or do I need to? to add to this I would need to change the probe pin configuration to active low, correct?
Thanks,
Justin

Here is a schematic and photo of wiring implementation.

I changed the 4.7k ohm resistor  to a 2.2k resistor and now the probe works...sort of.
I'm using the simple auto tool zero in the Mac3 2010 screenset.

• When not grounding the tool/spindle and just touching bob grnd to touch plate it works, but stutters a little bit on the first contact but finishes the routine and reads "Z axis is now zeroed"
  

• When grounding the tool/spindle with the bob grnd the routine runs and when the tool touches the touchplate it hesitates for a microsecond, like it did in the above scenario, but then continues down, even though it has touched the plate and the probe led is lit, the screen still says "probing for zero".
  I have to hit the E-stop to stop the probing routine.
  

There is continuity between the bob grnd and the spindle/machine at about 9M ohm. I don't know if this make a difference but I've heard that sometimes the spindle/tool needs to be isolated from the bob grnd. I've also heard that noise is usually the culprit in these situations. If it is noise wouldn't the noise trigger a false reading, stop the routine early and NOT ignore a real reading of a touch? Looking at the schematic in the previous post how would I add some noise suppression? Anyhow I'm out of my depth here and any input or suggestions would be greatly appreciated.
Thanks,
Justin

What version of Mach3 are you running?

The recommended version with the ESS is ...062 and not 066


I suspect that your problem (in part) is associated with the input schematic for that board....  If you look at the at the attached screenshot extract...

You basically have a voltage divider being formed .... so when you apply 5V to pin 15 via a 4.7k resistor.... the voltage seen at pin 15 is 2.5V  

<<<Ohms law >>>

by reducing the resistor to 2.2K.... you've increased the voltage to ~ 2/3rds of 5v, which is 3.4V

The datasheet for the Schmitt Trigger is here .... have a look at the switching voltages on page 5/21:
http://www.nxp.com/documents/data_sheet/74HC_HCT14.pdf

I would suggest using a 1kohm resistor.... presuming you bought a pack of 2.2k ohm resistors.... I'd join tow together in parrallel (side by side) ..... NOT SERIES!!....

As that would make the high side voltage 4.05V which is well above the threshold voltages...

(really they should have used a jumper so you could have removed the 4.7K resistor).

You can set your debounce quite short as the inputs have capacitors (especially for your "probe" input on the ESS config screen) .... hence when the probling function starts the capacitor will be charged to ~ 4.05 volts (as per my calc above).... and when the probe is grounded the capacitor will discharge in about 470 micro seconds  

.... note you must ground your machine when you are doing the probing function...

Rob

Oh dear...... Ignore  my above post....... I've made an error (over the grounding comment!!!!)  [[[distractions in the background whilst trying to type and multitask!!]]]

Thanks for the advice, I added a 2nd 2.2k res in series and now the touch plate is reading @ 4v however I still have the following issues:

• When not grounding the tool/spindle and just touching bob grnd to touch plate it works, but stutters a little bit on the first contact but finishes the routine and reads "Z axis is now zeroed"
  

• When grounding the tool/spindle with the bob grnd the routine runs and when the tool touches the touchplate it hesitates for a microsecond, like it did in the above scenario, but then continues down, even though it has touched the plate and the probe led is lit, the screen still says "probing for zero".
  I have to hit the E-stop to stop the probing routine.
  

How are you running the probe function.. Which mcode are you using or script



Have you got your machine setup correctly where
Z+ = up
Z- = down

Rob

Yes z+ up z- down,  I've had this working before, don't why it stopped working.

Have you got homing / limit switches .


What pins hae you got setup for the probe and homing functions?

(I am trying to remember what I changed 4 months ago when I had the same problem)

Rob