Quote Originally Posted by Doddy View Post
Problem sounds to be sporadic - unlikely to be something that can be diagnosed with a meter.

@Nr1: The things I'd look at:-

Sounds like you have potentially two problems - one of UCCNC registering an input when the input is inhibited?, that's my understanding from your description - and I'd try to resolve that first. If the e-stop, inhibited in UCCNC, is ignored from manual activation of the e-stop (i.e. it looks inhibited) but you're still getting random e-stops through, then I'd suspect the UCCNC software. Could you knock-up a Mach3 build and see if you get similar?
If, however, having inhibited e-stop in UCCNC, the e-stop control does work as you'd normally expect then clearly this is a configuration/software bug issue - try rebuilding your config etc (I've not used UCCNC outside of demo mode so don't know how easy this is?) - or, again, trial a Mach3 build to resolve if it's a software issue or not.

The other problem sounds like the sporadic triggering of the e-stop at an electrical level. Try to understand the software issue before you waste hours on the electrics...

You have two main signal paths: Control-to-the-BoB, and BoB-to-UCx00. The first path - it sounds like you've tried to address EMC/noise (though there can still be gotchas there - are you grounding the screen only at the control box side?, internally to the control box have you shielded that cable?). You could switch to 24V signalling by including a current-limiting resistor between the e-stop line and the BoB input - that would improve noise immunity, or put a (say) 1k resistor between the BoB input and ground to bleed any capacitive induced EM. I personally think this is unlikely to fix your issue.
What about the BoB-to-UCx00 - are you using the provided unshielded IDC cable (26w IDC connector, 25W D-Type IDC connector, 30cm of cable between)? - when I build up my control box I *will* be cutting this cable down to a minimal size to reduce the effect of cross-coupled signals from UCx00 outputs and UCx00 inputs. The UCx00 inputs are reasonably high-input impedance (though a 4k7 pull-up to 5V on board) - it's possible to get short pulses from the stepper outputs coupled to an e-stop input. Have you tried changing the e-stop input? - e.g. Input #13 on a port 2/3 is physically as far away from the stepper outputs on the IDC cable - cross talk should be minimised here. By grounding input #12 as well you're providing the best isolation for your e-stop as you practically can. Worth a shot to see.

Other ideas - try de-powering your spindle - and air-cut - see if that improves things - will indicate if your problem is EM related. Similarly, disconnect the outputs from the BoB to the Stepper Drivers to see if that affects it (causes: EM, or noise on the PSU lines).
Thanks for the input, loots of things to try :D

Im already using 24v system for limits and e stop. So it should be alright unless the bob is shit..
Am using unshielded ribbon cable and can try with another one.
But if there is faulty hardware then the problem should disappear when I disable the e stop port and pin.. strange!

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