Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: wdp67 on February 19, 2007, 11:19:33 PM

Title: trouble w/limit switches
Post by: wdp67 on February 19, 2007, 11:19:33 PM

Hi again all,
I am trying to hook up home/limit switches as per the new setup guide.
But I am having troubles. I have 5 switches but for now I have only
hooked up 3 in series as x,y,z home as per the set up guide. when i do
a ref all the z goes up till it hits the switch like it is supposed to,
but it does not back off of it and causes an e-stop instead.

Anybody care to help me out.

Thanks
Walt

Title: Re: trouble w/limit switches
Post by: Chip on February 19, 2007, 11:47:11 PM

Hi, Walt

Try setting your "Debounce Interval" to 1000 in Config, General Logic Conf. Page.

Your switch's NC in series, test good in Diagnostic window. ?

Hope this Helps, Chip

Title: Re: trouble w/limit switches
Post by: Hood on February 20, 2007, 02:39:49 AM

Have you also got the switches set as Home switches in Ports and Pins, Input  page?
Hood

Title: Re: trouble w/limit switches
Post by: wdp67 on February 20, 2007, 11:29:39 PM

yes, I have even disabled x++ and x-- and just left x home enabled and it still does it. It wont move off the switch and it doesnt zero the DRO. The other 2 axis's work right. Everything is wired the same, I just cant figure it out.

Walt

Title: Re: trouble w/limit switches
Post by: Chip on December 12, 2007, 01:07:59 AM

Hi Walt

In Home&limit's is the Auto-Zero "Checked" ?

Thanks, Chip

Title: Re: trouble w/limit switches
Post by: jimpinder on December 12, 2007, 02:39:18 AM

I take it you mean you have disabled Z++ and Z--. I had (or still have) the same problem but on my Z axis (but it is on the lathe so it is the equivelant of the Y axis).

I must admit my  homes worked alright after I disabled the limits. ( I only have two, both on seperate inputs - both wired directly for a 0v input)

I only use cheap micro switches and I am wondering if switch bounce is the problem in that switch acts as a lhome switch - it hits the switch, then reverses (fractionally) then switch bounce causes another signal which is interpreted as a limit switch. When does the program stop viewing the switch as a home, and revert to looking at it as a limit.

I know the "over-ride limits" allows you to jog both ways (even back into trouble) but would it be possible to re-write this bit of the program so that in normal operation you could always hit a limit then back off (ONLY). If it were then a home switch as well, the action is the same, it hits the switch thens backs off - but only til the switch opens/closes again.