Homing a rotary axis?

[Harryman]

Has anyone tried setting up a switch for homing a rotary A axis?

I've got a proximity switch wired up and I've tried a few things.

With the switch wired in as a limit, A will go lo and home fine like any other of the axis. I then can't rotate past the switch again without triggering it as a limit, that's a problem. It'd be great for Wincnc to acknowledge the switch just for homing and not as a limit, but I can't figure out a way to make that possible.

I then tried a hardware solution, I wired a toggle into the proximity switch so I can turn the proximity on and off and configured Wincnc so that with the switch on (closed), the limit is tripped hi and any limit change will stop the axis. Now when I home, it rotates low, triggers (opens) the switch, moves past the trigger point, the switch closes and moves off the switch a set amount. At this point, I can then turn off the proximity switch and rotate the axis freely.

The problem with this seems to be that it doesn't trip the switch, reverse itself and come in slow the second time. Since the limit is already tripped hi, it can't reverse. Even when I slow the approach speed way down, I believe I'm not getting accurate enough homing because it can't come in this second time. It also doesn't set MZ on A either when tripped like I'd expect.

Anyone have any ideas?

Thanks,

Harry

[Harryman]

I wired up a 3 way switch, one way the proximity switch is active, one way just completes the limit switch circuit via a ground so when the switch is tripped, it doesn't send an input to WinCnc. The third way,....nothing.

Works fine.