View Full Version : Tool Probe Connection - +24v to earth

10-04-2016, 08:30 PM
Hi all,

doing the last modifications on my machine and need some help on this.

currently I have a cheap prob which is basically a plate and a small clamp each with its wire and if you clamp the tool and it touches the plate I can hook them up to a +24v and pass it to my controller as input, I'm sure you all know this concept heh.

would it be possible/safe to just connect the plate to the +24v input and the the input port to earth? that would eliminate the need to clamp the tool and just make it a bit more professional.

I'm thinking of doing this because the whole machine is already grounded/earthed by virtue of spindle ground wire ( I think ) and all the metal bodies in contact. but I just don't know if it is safe or good practice to have earth be connected to the + port of the input pin. can some high voltage pass through which would damage it?

the controller is CSMIO-M so the input port has a + and - pins and the - is connected to the common ground of all my +24v lines.

10-04-2016, 09:17 PM
I am pleased you have raised this problem as I will have to do something to give the same effect. Reading through the CSLabs manual for the CSMIO IPS leads me to believe that the solution is to put 24v to the input +ve, but through a current limiting resistor. This can be fairly large, and I would suggest 3.3k ohm. then you can put the probe to the +ve input and when the tool touches the grounded probe it sends the input low and triggers Mach3. The input -ve goes straight to ground.

I hope that if this is not a safe solution then someone on the forum will shout.