IP/M, Mach3, and wireless MPG

[Neale]

On the whole, my router with the above configuration (IP/M, Mach3, wireless MPG) works pretty well, and even better after someone pointed out how to home master and slave axes. I run a version of Mach3 (can't remember exactly which one at the moment) which is not the latest but which allows me to successfully use my tool-change macros - something was broken in this area in the latest Mach3 releases when using CSMIO controllers.

I have two problems. The first is that having homed the machine, unless I jog off the home position with the MPG, I get "hit limit switch" errors as soon as I try to move any axis, whether that's running a job or jogging with Mach3. I don't see which limit switch is claiming to have triggered on the Mach3 screen. I have to rehome and start again. Use the MPG - no problem!

Second issue is that I often get "soft limit" warnings when starting a run, even when it is not the first time I have run it and nothing has changed. I usually have to shut down Mach3 and start again.

None of these are show-shoppers (although the second one is a pain in the neck) and I doubt that there is a fix, bit I was wondering if anyone else sees anything like this? It would be good to know that it's not just me!

[JAZZCNC]

I have two problems. The first is that having homed the machine, unless I jog off the home position with the MPG, I get "hit limit switch" errors as soon as I try to move any axis, whether that's running a job or jogging with Mach3. I don't see which limit switch is claiming to have triggered on the Mach3 screen. I have to rehome and start again. Use the MPG - no problem!

This one is easy enough. In homing and limits use the home Off option and it will backoff the switch what ever amount you enter. Then Zero the machine coords.

Second issue is that I often get "soft limit" warnings when starting a run, even when it is not the first time I have run it and nothing has changed. I usually have to shut down Mach3 and start again.

This one I'm not so sure about. I've had similar things happen from time to time but cannot figure out why. Usually, thou when it happens just re-homing and everything's good.

[Neale]

This one is easy enough. In homing and limits use the home Off option and it will backoff the switch what ever amount you enter. Then Zero the machine coords.

Thanks for the comments, Jazz. Unfortunately, I don't think that this is the answer. You told me about this one a few years ago when i first built the machine. I have it set to home Z, then X and Y together. I had the problem that the Z home/limit switch was a bit sensitive and once the gantry started moving after homing Z, it tripped. I fixed that as suggested. I've just been out to the machine and done a few experiments. Even with a homing offset of 10mm on all three axes, I get "limit switch triggered" if I use the MDI to move away from the home position. Same thing if I jog any two axes away from home with the MPG first. If I jog all three axes away, it works fine. Makes no sense to me!

This one I'm not so sure about. I've had similar things happen from time to time but cannot figure out why. Usually, thou when it happens just re-homing and everything's good.

Been experimenting with this one as well. I homed the machine, did a "regen toolpath", and hit Start. Soft-limit warning. Rehome, regen toolpath, jog machine with MPG off home position in all three axes - works OK. I suspect that what might happen is I often start a job after jogging to roughly the right area with the MPG in X,Y, but leave it at Z home position. In future, I shall try to move off Z home before starting the run and see what happens.

I'm running 3.043 as the later versions don't work properly with the IP/M. Not sure if there are other places where it fails but I know that later Mach3 versions can't handle tool height setting between M6Start and M6End, which makes it a bit difficult to use if you need to change tools. Maybe the MPG plugin complicates things as well, but it's too useful to give up! My money is on an internal software problem that only shows with this combination of hardware.

If the IP/M blew up, I would swap for UC300ETH/UB-1 which looks like a fairly straightforward change (24V signalling, etc) but the IP/M is so bullet-proof that it will probably still be running when the rest has crumbled to dust...

[JAZZCNC]

Thanks for the comments, Jazz. Unfortunately, I don't think that this is the answer. You told me about this one a few years ago when i first built the machine.

Yes, I thought I had mentioned it before.!

've just been out to the machine and done a few experiments. Even with a homing offset of 10mm on all three axes, I get "limit switch triggered" if I use the MDI to move away from the home position. Same thing if I jog any two axes away from home with the MPG first. If I jog all three axes away, it works fine. Makes no sense to me!

Ermm it's a odd one indeed, I'd look at the switch wiring to make sure you haven't got a bad joint or something daft. Possibly a switch on it's way out.?
Could try using a little De-bounce in the plug-in to test if it's noise, and if that works and woring ok then I'd suspect a switch going down because you never need to use De-bounce with IP-M if wiring and switches are good.

[Neale]

Yes, I guess there's a chance that it's a switch. I bought a box of 10 cheap from China. One was dead on arrival, one failed soon after fitting, and one was completely the wrong type (only two wires was a bit of a give-away). They've been on there for 3-4 years now but even if the switch is good,wiring could be the issue. I've done a fair bit of electronic wiring and building in my day, as well as being in IT for my working life, and this one smells to me like software. I reckon that it's a bit of confusion about limits going on somewhere on the Mach3-IP/M boundary and both my problems are aspects of the same thing - just that one shows up as a hard limit trip and one as soft limits. It's not a million miles from the problems with tool-height setting during an M6 where the later versions of Mach3 get their coordinates in a twist.

Whatever - no-one's going to fix it but if I can understand how to reliably work around it, I'll be happy. Although i was looking at the UC300/UCCNC manuals earlier and I hadn't realised that they've sorted the master-slave homing problem as well. Maybe next year Santa will bring me a UC300/UB-1, I can try to remember how I wired the IP/M originally, and I'll do a heart transplant on the control box.

Thanks for your comments - haven't found the answer but it's helped me think about it differently instead of just cursing every time it goes wrong when I'm in a hurry to do something