Noise comes from lots of things; we know that already, data wires are what picks up this noise and causes havoc to the very sensitive Parallel port.
Now if we think about it, no professionally made machine has data wires running all over the place like most hobbyists insist on doing, if we don’t have data wires, then we don’t have problems with noise.
Ok, how.
Motor wires create noise, but not affected by it, so we can save on the shielded wire here.
Limit switches are nothing more than a safety switch, so why not wire it up like one,
One or two E-stop switches and all limit switches, all wired in series (24 volt), no problem with noise, again shielded wire isn’t needed.
Home switches (wired parallel) of any type can be found in (24 volt) versions, again no problem with noise, no shielded wire.
E-stop and limit switches should always have their own hard wired circuit fully independent of the computer, but it is also an advantage if the computer receives the E-stop signal as well.
In the control box the E-stop circuit uses a large relay, by having another small 24 volt relay connected in parallel very close to the breakout board, now it’s here we have data wires, very short, no problem with noise, no shielded wire, and we do the same with the home circuit, another small 24 volt relay.
PS:
Limit switches are something you don’t run into every day; in fact you shouldn’t touch them at all,
just like E-stop they should be wired closed (the safest way), a strong switch with a solid ramp that can force open a sticking contact, wired this way a loose contact or a broken wire will create an E-stop.