Help with G-540 and xyz probe

[dragonfinder1]

 Using the xyz probe, From the CNC Zone, I' tried and tried with no avail to get any connection from my Gecko G-540  (1 through 4  pin #s 10 through 13 ) through to Mach. I see many other people have successfully made this mod. I get  12 volts from connections 1-4 to ground, but I cannot get the led to light. It seems as through Mach, those pins are not working.

I've asked for help over at CNC Zone, but no one has answered. I'm sure this could be easily fixed and that it's something simple, I just don't what to do.

Anybody have any ideas?

Dave

[rrc1962]

I have a probe set up on a G540.  It is connected to one of the G540 inputs and mapped in Mach according to the G540 instructions.  Make sure your PP is in EPP mode.  Some features of the G540 won't work unless in EPP mode.  That could be one of them.

[whitehedr]

To test the input you are using for your probe connect a wire from the terminal block to ground using a pushbutton switch.  Make sure the input is turned on by the config ports and pins page.  You might want to assign the input as one of the limit switches.  Go to the diagnostic page, activate the switch and you should see the LED toggle.  If the LED does toggle then you need to look at the XYZ probe and see how it is hooked up in relationship to the G540.  Is your G540 grounded to the machine?  IS the XYZ probe getting its logic voltage from the G540 input pin or are you trying to opto isolate the signal?

RWW

[dragonfinder1]

Yes I am in EPP mode. I've tested all the inputs on the G-540 with the correct pin numbers on the config page and none will light the led for the probe, I checked the diagnostic page and none of the leds lit up. I haven't tried to use it as  a limit switch, I'll try that in the morning. The inputs on the G-540 all have 12 volts to ground, I don't know how to opto isolate signals, maybe I should.

Dave

[mqbeers]

I had this same issue a couple of weeks ago when I went live with my G-540. I had previously been using a Hobby CNC Pro controller and had no issues with the probe lighting the LED on-screen. Could not get it to happen until I ran a ground wire from the common (ground) terminal on my terminal block where I tie on to all the G-540 ports and put a clip on it that I clip to the router mount. Works flawlessly now. Not sure why the router and the G-540 do not seem to see the same ground, but this was an easy, if not particularly elegant, fix.

In order to use the probe now I just clip the ground wire to the router mount and run probe routines.

Don't know if this will help, but good luck.

[Jeff_Birt]

'GROUND' is NOT the same thing as 'DC Common'. The inputs on the G540 need to be pulled low, that is - connected to the same DC Common as the G540, to work properly.

[mqbeers]

Thanks Jeff. Not an electronics guy so surely got my terminology confused. Still learning about "Pulled Low", etc. and what that all really means. I think it is pretty cool that even an electronics idiot llke myself can kludge together something that appears to work.
What I can say is that all my inputs are connected to the same "DC Common" as the G-540 and my probe works with an additional wire run from the DC Common to the router mount that I clip on when I need to use the probe. Would love to know another way to do it without the additional DC Common wire if you would care to share that.
Thanks.

[dragonfinder1]

I found the problem, stupid wiring error.  Computers only do what you ask them to do. Thanks to all for the help. I knew if the probe worked for every it should work for me.

Thanks again

Dave

[Jeff_Birt]

What I can say is that all my inputs are connected to the same "DC Common" as the G-540 and my probe works with an additional wire run from the DC Common to the router mount that I clip on when I need to use the probe. Would love to know another way to do it without the additional DC Common wire if you would care to share that.

If your using a solid probe, that is one that works by making electrical contact between the probe and workpiece, then you really need one wire hooked to the workpiece and one to the probe. Never try to use the machine frame as a DC Common as most likely it will be bonded to (earth)ground.  If you try to run a signal back through (earth)ground you'll cause all sorts of problems.

[mqbeers]

Thanks again, but color me confused. The clip that goes on the router is attached to a wire that goes to DC Common. This is the same place that the limit switches complete their circuit. I have an aluminum plate that sits on top of whatever wood I am working with and that has a wire attached to it that is landed on terminal 3 of the G-540. The signal is generated by the tip of the router bit lightly contacting the aluminum plate to set the Z Zero. I think the only way for me to use this system is for the router frame or bit to be connected to DC Common so the signal can complete when it touches the aluminum plate and then it is disconnected immediately thereafter. My G-540 has no physical connection to earth ground

At what point is the signal going back through earth ground? I cannot see where that would be the case but am extremely eager to learn. I have read through the debate that you and Mariss engaged re: machine grounding and connecting to earth ground and I am unable to trace where in my setup that earth ground is anywhere near the DC Common.