Try changing the z axis settings on the homing and softlimits settings page under configuration...

There is a checkbox for negative home, can't remember if toggling that solved my problem (I had two at the time the z was crashing int o the top of the carrige but that was the safe home setting...)

yep, I've got homing switches that work, x Home  pin 11, y Home pin 12 , z Home pin 13, probe pin 15, all on port 1. Homing is active high and probe is active low.

Try changing the z axis settings on the homing and softlimits settings page under configuration...

There is a checkbox for negative home, can't remember if toggling that solved my problem (I had two at the time the z was crashing int o the top of the carrige but that was the safe home setting...)

I'll try that but I don't think that's the issue. the auto zero macro works, more or less, when the C25 grnd is NOT touching the tool/spindle and I touch it to the touch plate, that is I start the macro, z goes down towards the table, -z, until I touch the bob grnd to the touch plate, z stops then it does it's double touch routine then retracts to 1.5" above what it thinks is zero. Now when the bob is grounded to the tool/spindle and I run the macro when the tool hit the touch plate it keeps on going even when the probe led is lit and I have to hit the e stop to keep from crashing into the table.

what version of Mach3 are you using?

(other than that I'm out of ideas).

what is the code you are using if it`s not coded for you screen it wont work to well put it in code tag's

what version of Mach3 are you using?

(other than that I'm out of ideas).

Version R3.043.062

what is the code you are using if it`s not coded for you screen it wont work to well put it in code tag's

I'm running the 2010 screenset.

Like I said before I'm totally new to all this, especially the electronics part. A little back story here. I bought a Chinese machine with an AKZ250 motion controller card, set up the auto zero probe with an external power supply (9 volt battery) and it worked, and then one day it didn't. I swapped out the AKZ250 card for an ESS/C25 combo and the auto zero still didn't work, played around with it, re calibrated the motor tuning and it started working, just not consistently. I moved the touch plate grnd lead from the front of the table to up onto the spindle mounting plate and the auto zero stopped working. Now if I were reading this I would think that this would be a noise issue because now one of the probe leads is running past another stepper motor and a spindle however I believe there is pretty good noise suppression on the C25 board and I'm running 5v through 2 2.2k res in series to the touch plate. What I am thinking now is that there is a grnd loop issue because  the auto zero macro runs as it should when the C25 probe leads/touch plate is isolated from the table, spindle, tool, and doesn't when the grnd lead from the C25 is touching the table, spindle, tool. Does this make sense? If this is indeed a grounding issue how would I go about fixing it, or even testing it beyond the test I've done?
't

.... Can I make a suggestion.... Why not use a crocodile clip onto the tool when you want to use the tool offset / probe function

Because at present you are relying upon conduction through the spindle bearings and spindleshaft to the tip of the tool.

Then put the 5v (pin 13 or 15 input..forget which one you are using) to your insulated calibrated height block.... (You could use a piece of blank PCB (printed circuit board)....

Try that...

Why not use a crocodile clip onto the tool when you want to use the tool offset / probe function

I am using a crocodile clip on the tool or when the tool is to big for the clip I clip it to a bolt head on the spindle mount, but for the testing I have been clipping to the tool. To add a little more to my grounding theory if I touch the ground to the tool in the middle of the zeroing macro I can feel the machine react to the contact, not much, but there is something happening and this is long before the tool reaches the touch plate.

Then put the 5v (pin 13 or 15 input..forget which one you are using) to your insulated calibrated height block.... (You could use a piece of blank PCB (printed circuit board)....

you just described my setup as it stands now, although my circuit board is loose so I can move it around to the work piece.

so you have a clip that goes to the tool what is earth (common) and the signal wire going to the touch plate.

do you have your earth wires going to a common star point earth is -common or just common.

also what is the voltage between the clip and the plate if it is below 2.8vdc that might be the problem.

if you just touch the plate to the spindle noise does anything happen or the frame of the machine, if you touch the plate to the spindle and it works you don't need the clip if it does not do anything you need the clip.
if it works when you touch the plate to the machine frame good if it is still just as bad, check all you wiring to make sure you only have single ended shield wire`s no broken wires just a good look over.

gerry's code is fine it will be nothing to do with that.

a ruff way to check to see if it is a noise (RF) problem put a fm radio on the machine (have it turned off) tune to a radio station turn the machine on and if it goes stac you have a noise problem if the radio is fine it`s to small for the radio to pick up so all good.

I suspect it's a ground loop problem.... You may need to try to put the ESS on its own 5v power supply so as to separate both sides of the breakout board optoisolators.

Have you got a separate 5v power supply you could try?

Rob