Wouldn't dare try teaching granny to suck eggs! But sometimes talking through a problem with someone who doesn't really know what you are talking about kicks off that Eureka moment. Didn't realise that the problem wasn't basic network connection (although my software found the board without me doing any config apart from setting laptop IP address in the right subnet) but myCNC talking to it. Starts to sound a bit like a hardware/firmware problem at board level? I'm also using the latest download of myCNC but haven't (yet) seen anything like that.

I fixed my e-stop/safety relay problem last night (and I really don't like to admit publicly to official Muppet status, but really I should have checked that *all" the e-stop buttons weren't locked in...). I also remembered that I took the fault output from the drivers to the "servo fault" input on the IP/M so I need to check how to configure that on the ET6. I think it's on the "Alarms" config page. About 2am, I realised the answer to an associated problem which comes from a difference between IP/M and ET6. I had hoped that I would need minimal wiring changes (if any) in the swapover - same 24V signalling, differential outputs, etc. However, the IP/M exposes both ends of each opto-isolated input so you can choose how to connect on an input-by-input basis. The ET6 groups input into blocks of 4. Each opto input has back-to-back LEDs so they are polarity-insensitive but each group has one end of all LEDs tied together to go to + or gnd according to requirements. That's fine for the limit switches which is one block of four, but then I have e-stop input from relay, touchplate, and driver fault. My previous logic needed different connections for touchplate (shorts to ground, of course) and the other two switch to +24V. However, it's farily trivial to modify those so that I can use a group of inputs with the common end to +24V and switch to ground for the inputs. One little puzzle out of the way.

Would all have been a touch easier if I had not lost my printed copy of the IP/M manual where I had listed all connections, wire colours, etc. Never did have a proper wiring diagram, just a few sketches and did the rest off the top of my head. Both unreliable record-keeping mechanisms...