limits and home sw

[eloid]

i have see alot schematics with just limit switch no home sw or limits switch all in series on one input....
can some please tel me know what pro side of have all litims +,- on each input of a breakout bread also have home switch per input...


I have see very few drawing that use home sw why?

[LaserImage]

Home switch = a way to accurately set 0,0,0
Limit switch = a way to keep from overunning the physical limits of your machine

You can have either, both or neither, but for safety sake you should have at least limit switches. - and, of course, an e-stop.

There is no need to have separate switches all wired separately to your BOB. Whether it is a limit or home, Mach does something when a switch is triggered. If it's during the "ref all home" then it moves each axis until a switch is triggered and then moves to the next axis (z, y then x, I think). If it's during normal operations then everything stops when a switch is triggered - doesn't matter which one, it just stops.

Gary

[eloid]

thanks gary
that helps, next question is there a way you can wire up 2 limits switch per axis,,, and also use them as a home.... to reduce wiring and cost of switch and wire?

[LaserImage]

Better yet, how about 1 switch per axis?

If you use hall effect switches then you just mount one switch and have a magnet at each end. Same thing with a mechanical, roller switch - one switch and a "ramp" on each end to trigger the switch.

Run the wires from each switch back to the bob and do your series connections there. If something doesn't work then you can still wire them individually.

Gary

[acondit]

thanks gary
that helps, next question is there a way you can wire up 2 limits switch per axis,,, and also use them as a home.... to reduce wiring and cost of switch and wire?

EMC2 supports that. On my router, I have a limit switch at each end of the travel on each axis. So 3 axii, 6 switches, and 3 input pins. They are NC switches wired in series. The limit switch at the home end of the axis serves dual function as both home and limit. The control software knows when it is trying to home and therefore recognizes the switch as home rather than limit during that operation. With a little thought you could do it with just three switches (and they wouldn't have to be hall effect).

Alan