Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: gskinner on June 29, 2008, 06:59:29 PM

Title: Zero plate problem
Post by: gskinner on June 29, 2008, 06:59:29 PM

I am trying to add a touch plate using the XYZ probe modification from the CNC Zone forum.
The problem I am having is Mach always sees the digitize input as always active (status light on) even if I unplug the parallel cable.
I do have the probe input pin set to active low.
I have Mach on a computer in my office and with the same settings the digitize input is not active (status light off).
Have the same version on both computers and have also tried different versions and reinstalling.
If I change the input to active high the light just stays out and the touch plate still does not work.

 Any ideas?

 Thanks
 George

Title: Re: Zero plate problem
Post by: Hood on June 30, 2008, 03:13:12 AM

Check to make sure you dont have any other inputs set up for the same pin.
Hood

Title: Re: Zero plate problem
Post by: da21 on June 30, 2008, 03:29:19 AM

are you using an opto isolated breakout board , this usualy inverts the signal , or could be that the pin is pulled high by a resistor to your 5v , modifying the board by removing the resistor or swapping it to 0v instead of 5v may help , let us have more information on your breakout board etc

Dave

Title: Re: Zero plate problem
Post by: jimpinder on June 30, 2008, 04:13:54 AM

The input wires on the LPT1 pins are normally kept high by internal pull up resistors in the computer.

It may be there is an internal fault on your LPT1 port. Disconnect you cable and test the port, check with a voltmeter whether the pin is high or low. Make sure (as Hood says) you have not inadvertantly also applied it to some other function before you test it.

The settings on Mach 3 make no difference to the actual voltage on the pin, only if that pin is recognised as active or not.

Lastly - try another pin, if you have one spare.

Title: Re: Zero plate problem
Post by: gskinner on June 30, 2008, 12:54:33 PM

Thanks for the help.

I did already check to make sure the pin was not being used by something else but will double check it.
I do not think it is the breakout board as I have the problem even with the parallel cable disconnected.
Maybe I will assign the probe to another pin and see if Mach sees it any differently and that will also help to confirm if it is a computer motherboard problem as the parallel port is on the Motherboard.

Thanks Again
George