Connecting to a CNC machine, pros and cons of USB vs PP vs Ethernet etc.

[Jess]

I think theres a little bit of a thing against laptops in the CNC world which comes from the problems you used to get with parallel ports on them

I think the parallel-port-voltage-thing was often solvable using a decent breakout board.

However, there's another reason: system management/maintenance interrupt 'stuff'. It's the utter enemy of anything that needs to be 'real time'. It's the usual reason for, say, a very slight pause every 30 minutes, or a little hitch whenever the processor gets slightly warmer and the fan speed needs to be increased or if there's a battery fault or...

Whilst all new machines seem to have more 'going on' in terms of SMI tasks, laptops tend to lead this trend, so it's just that poor performance or unreliability is more likely with a laptop.

It's less of a problem with a motion control board as that can hide smaller latency based sins but you really don't want to be a few hours into a milling job only for an intermittent computer problem to mess it up.

I did try a laptop, and the latency was fine...except for a very occasional (like once a day) SMI interrupt which put it it 'useless, even with a motion control board'. (You could also trigger it if you used any of the special laptop keys (like the screen brightness ones etc.,).