Touch probe woe's

[JohnHaine]

Great, well done! MOSFETs are nice devices.

[Neale]

It is a little-known and barely documented fact that there is one version of Mach3 that is able to support two probe inputs with independently-set parameters (active low, etc). It might well be easier to combine the two inputs electronically as already described here, but I bought a second-hand CNC mill whose control box had separate inputs for touch probe and height setter, so I needed to explore how it was done - particularly as I wanted to modify the probing routines to suit. I did consider the electronic signal combiner, but on my machine the input sockets were directly connected to a custom motherboard that would have been difficult to modify, and an outboard box would just have been a bit of a fiddle. And the existing machine ran with the "two input" configuration, so it needed exploration! By going through the provided probing routines, I found that they used an undocumented Mach3 feature that allowed a macro to switch between inputs to select an appropriate probe and I was able to adopt this to use in my own probing code. I wrote it up here.

If you feel happier with electronics than code, then the external signal combiner is probably the way to go, but I like fiddling with both and was happy to find a software solution!

Then I scrapped the ESS and replaced it with a UC300ETH and UCCNC software, which support two probe inputs out of the box, so the problem just went away!

[Smokie555]

That interesting on the Mach 3 versions. I've been fiddling with this on and off for a while and must have got a little muddled up as once I finally got a setup that Mach3 could see (above) it turns out the active low setting is working just fine with both the probe and touch plate which is great. Now using each probe is just a matter of plugging in the one you want and off you go, fantastic. Thanks for the link to your write up, all interesting stuff.