Re: Pullup resistor on a NC touch probe, Mach3?

> Pullup resistor on a NC touch probe, Mach3?
> Posted by: "Monte" montejw@... montejw360
> Date: Fri Apr 11, 2008 11:56 am ((PDT))
>
> Longtime lurker here. Would a pullup resistor be a good idea on a NC
> touch probe? I'm thinking it's just like a limit switch to Mach.
> Plus I'm not sure if connecting a NC switch directly to the parallel
> port is good. Running Mach3 and the probe is on pin 11. Then, with a
> pullup resistor, would it be active low, or high?
>
> Thanks,
> Monte

The pull up resistor is necessary. Without it when the switch opens the
pin is just floating, nothing causes it to go to a high condition. With
the pullup when the switch is open the resistor pulls the pin to +5 volts.

If the probe switch is closed when the probe is NOT touching anything,
then this would be an active high signal- it will normally be at ground-
low- until the probe touches something, then the pullup causes it to go
high.

ron giger