ESS and multiple probe inputs

[Neale]

I've been doing some digging and experimenting on this. I'm going to document my thoughts and findings just in case someone else - so many years after Mach3 was officially obsolete - happens to want to do the same thing.

Problem - I have a Mach3/SmoothStepper setup, with a probe and a toolsetter connected to different ports on the ESS. How can I use G31 probe commands for both probing and tool-height setting without going into "ports and pins" to reset the probe input setting each time?

I started with a possible electronic solution. Take both inputs, clean them up (Schmitt trigger?) and combine the outputs (possibly nothing more complicated than a couple of isolating diodes) into one output. Not easy to do outside the existing control box as I would need a 5V supply. Not really difficult but a bit messy. So put a small board with relevant components inside the box. I find that all the signal connectors are actually mounted on a motherboard so not easy to break into the existing pin connections to go to my proposed signal combiner. I also notice that the ESS board is not quite standard. They have turned over two of the 26-pin ports so that they are on the print, not component, side of the board so that the ESS actually plugs on to the motherboard to pick up all the active signals. However, the third port has been left on the top of the board and is accessible. So, an electronic solution would be possible but a bit messy with either an external box plus PSU or hacking the motherboard.

Next thought - how about using Mach3 brains? That is, the Mach3 version of a PLC capability. So, quick brain thrown together so that the two input signals are OR'ed together and feed the Probe input as their output. Doesn't work - the probe input doesn't seem to respond. Fiddle about with various options for probe (enable/disable/port+pin settings, etc) but can't get it to work. Seems like, in common with most motion controllers, the ESS takes over the probe input and monitors it in firmware, and the brain output is ignored. No way forward there.

But what if I direct the brain output to a pin on the currently-unused port 3? Then connect that output pin to an input pin, and use that as the source of the probe signal? Sounds promising, especially as the port has a pair of adjacent input/output pins that I can connect with a standard .1" pitch jumper. Try that - the dianostic screen shows it all working, but when I come to run the various macros, it does not work as expected. I do eventually notice that after running the tool-height macro, the probe input pin has been reset to match the TH input pin. How did that happen?

Back to the macro and start reading the code more carefully. I find something I've never seen before - the SetInputData command. Can't find any documentation on it, except for a single comment that it seems to have been introduced in version .066 - the last one released. The comments in the macro code around it give me a clue - it appears to select a specified port and pin for the Probe input. This is probably why I was seeing the probe input definition changing during testing. I keep the TH macros as they are, and modify the probing macros (I'm using the Probe Wizard freeby set for probing) to use the same command but switching to the external "probe" pin before G31 is called. And now, when I run a TH macro, it uses the TH setter on the machine bed, and when I run a probing macro (any of the dozen or so that I had to modify), it uses the probe input. Magic!

I reckon my brain-to-ouput-pin-jumper-to-input-pin would have also worked, but it came down to using a brain and a jumper plus modifying the TH macros or just modifying the probing macros. I took the second approach, which does involve using a command that I cannot find documented, but it works fine. Now, the last job remaining is making a new probe and spindle for the actual probe itself which I managed to break during testing, when the input didn't switch when it should...

As I say, no idea if anyone will ever use this information but seemed better to publish it than sit on it, just so that Google can pick it up one day for others to maybe use.