wiring limit switches

Hi

I'm doing some work on the router and decided to put in limit switches. It looks like you run 5v thru them back to a unused port on the breakout board and use stepconfig to assign "e-stop in" to that pin. Am I close ?

Thanks
Paul

'

E-stop is a separate signal. The limit signal or signals get used with the limit feature of the software. You can wire up all the sensors or switches to a single limit input or have each end of each axis wired to separate inputs. PCI parallel port inputs are cheap so I tend to not skimp on inputs. If you wire up limit switches separately, LinuxCNC will know what end of what axis has tripped and act accordingly. If you wire up all the sensors on one input, LinuxCNC won't know and will assume all limits have tripped.

You can have pretty much anything you want between the the limit input and the sensor or switch. Usually the input terminal will work with 5 Volts, but some parallel ports run at 3 Volts. Running 12 Volts, a la RS232, through the sensor may offer more noise immunity, then convert to 5 Volts at the input. Or run balanced differential signals such as with RS422/485 and use a transmitter on one end and a receiver on the other. If noise is still a problem, there is a software debouce component that might help.

Ideally, you home your machine with the same pose every time you start LinuxCNC, then use the soft limit feature in the .ini file. This way the soft limit will trip before reaching the firm (sensor) limit or hard limit, and you can easily back off the limit.
--
Kirk Wallace
www.wallacecompany.com/machine_shop/index.html

Thanks Kirk
I think I will wire them separately

Paul