Re: [CAD_CAM_EDM_DRO] limit/home switches

Matt,

My home switches are simply connected directly to the parallel port.
I have no pull up resistors connected. But I have had some problems
in the past, before I shielded the wiring, with false trips while homing.
Since I shielded the wires I have had no problems with false trips. If
you have short wires and good shielding you can probably get by
without pullups, but it can't hurt to have them.

I have a CNC router, and am using some pretty good
home switches, but they are only accurate to .020" or .030".
That is good enough in my case but may not be OK in your case.

Bill

> Question for you EMC guys - do the various switches need to be

opto-isolated

> from the parallel port, or can the simply be hooked directly to their
> respective pins?
>
> Does the parallel send/receive 12 or 5 volt signals?
>
> If 12v, can one power the switches from a seperate power supply and hook
> them to the individual pins, i.e. pin 10 for the limit switch? I can get

5v

> from the same power supply easily enough, assuming the switches already on
> my mill (series one cnc) are 5v.
>
> Sorry for the seemingly silly questions, guys, just trying to figure out

the

> rest of this EMC setup!
>
> Thanks,
>
> Matt King
>
>
>
>
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