I am using mach3 with machblue.set.
I set up my probe and grounded the mill head so that the tool tip could activate on my probe plate.  When I activated the probe ... it went down to touch and when it made contact ... it tried to go down instead of retract the standard distance?  I had set the thickness of my probe plate as a positive number. 

What is going on here?  Why did it go down, touch off, then go down more instead of retracting.  Sometimes it works correctly.... sometimes not.  I don't think I have any noise on the lines and even if I did ... would this happen?

Could relative vs absolute gcode setting have anything to do with it?

Any feedback/advice appreciated.

You would really need to attach the VB you are using for the probe routine, someone may find a problem with it.
Hood

Just a guess but if the Z axis DRO has not been zeroed (suppose it reads 50.0000) then the Z axis will go down to get to 5.0000 (or whatever your touch off standard distance is) rather than up.
Unless your probing routine takes care of the G90 / G91 then yes it will make a difference.
As Hood suggested post your VB and check that you have everything set correctly in the screen set.

Tweakie.

Do I need to zero before using the probe?
That would explain the random behavior.  Can anyone confirm this?  I will run some tests when I have time.

Here is the code executed in machblue.set when I click the probe icon...

Rem VBScript to probe in the z axis

If GetOemLed (825) <> 0 Then 'Check to see if the probe is already grounded or faulty
Code "(Z-Plate is grounded, check connection and try again)" 'this goes in the status bar if aplicable
Else
Code "G4 P1" 'Pause 1 seconds to give time to position probe plate
PlateOffset = GetUserDRO(1151) 'Get plate offset DRO
CurrentFeed = GetOemDRO(818) 'Get the current feedrate to return to later
Code "F4" 'slow down feedrate to 4 ipm

Rem Probe in the z direction
ZNew = GetDro(2) - 2 'probe move to current z - 2 inches
Code "G31Z" &ZNew
While IsMoving() 'wait for probe move to finish
Wend

ZNew = GetVar(2002) 'read the touch point
Code "G0 Z" &ZNew 'move back to hit point incase there was overshoot
While IsMoving ()
Wend

If PlateOffset <> 0 Then
Call SetDro (2, PlateOffset) 'set the Z axis DRO to  plate thickness
Code "G4 P0.25" 'Pause for Dro to update.
ZNew = PlateOffset + .25
Code "G0 Z" &ZNew 'put the Z retract height you want here
Code "(Z axis is now zeroed)" 'puts this message in the status bar
End If

Code "F" &CurrentFeed 'Returns to prior feed rate
End If

Yes, zero the Z axis DRO before using the routine. Better still include DoOemButton (1010) at the start of your code.


Tweakie.