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Author Topic: Homing Probem  (Read 5326 times)

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Homing Probem
« on: August 23, 2008, 07:35:53 PM »
For some reason I cannot explain, I started having a problem with homing today.  Most of the time, it works correctly, but several times today it would start to home the Y axis, and as soon as it hits the home/limit switch, it stops, flags the limit switch triggered, and stops dead in its tracks.  When I try to manually clear the limit error and back out, I can clear the error, but the instant I hit reset, it re-asserts the limit error, and I am unable to back off the limit.  I could find nothing to get me going again other than killing and re-starting Mach3, whereupon it works correctly.  When Mach3 comes up the second time, it flags "Driver Watchdog Triggered".  It seems like something in Mach3 is getting whacked, because even if I power down the servos and manually back off the limit, it will just do the same thing again until I restart Mach3.
Why is this happening, and why did it just start today?  It's been working correctly for several weeks, and I've changed nothing in Mach or the limit/home hardware.  I have one set of switches, wired in series, for both home and limit on both X and Y.  It happened to me at least 6 times today.

Regards,
Ray L.
Regards,
Ray L.

Offline Chaoticone

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Re: Homing Probem
« Reply #1 on: August 23, 2008, 10:35:13 PM »
Ray, In config, general config. do you have a debounce value entered? If not, set it to 2000 and let us know how it does.

Brett
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Re: Homing Probem
« Reply #2 on: August 23, 2008, 10:46:38 PM »
Brett,

    I'll give that a try tomorrow.  Thanks!

Regards,
Ray L.
Regards,
Ray L.

Offline jimpinder

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Re: Homing Probem
« Reply #3 on: August 24, 2008, 04:35:40 AM »
On the "settings" page make sure "auto limit overide" is flagged. This allows you to "back off" a limit switch.

Is the problem always with the same switch. If it is, the switch is probably "noisy" and giving multiple on/off signals as it opens - hence checking the "debounce" as Brett says. If it is not too much trouble you can replace the switch.
Not me driving the engine - I'm better looking.
Re: Homing Probem
« Reply #4 on: August 24, 2008, 10:13:31 AM »
On the "settings" page make sure "auto limit overide" is flagged. This allows you to "back off" a limit switch.

Is the problem always with the same switch. If it is, the switch is probably "noisy" and giving multiple on/off signals as it opens - hence checking the "debounce" as Brett says. If it is not too much trouble you can replace the switch.

Auto Limit Override is set, but doesn't help when this happens.  The problem always occurs with the same switch, but it's the first axis that homes, and when in this state, it never makes it to the others.  The diagnostic page shows the limit is postiviely asserted.  Re-starting Mach always gets it working again, so I don't believe it's a noise problem.  It's a bug in Mach.  From posts on another forum, I'm not the only one seeing this problem either.  Someone else is having it on both his lathe and mill.

Regards,
Ray L.
Regards,
Ray L.

Offline Chaoticone

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Re: Homing Probem
« Reply #5 on: August 24, 2008, 11:39:24 AM »
What version of Mach are you running?

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Hood

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Re: Homing Probem
« Reply #6 on: August 24, 2008, 03:35:54 PM »
please link us to the other forum so that we can see if there are any common factors that you all share.
Also please post your xml so that we can look and see if we find any issues.
Hood
Re: Homing Probem
« Reply #7 on: August 24, 2008, 09:34:44 PM »
Hood,

    The other forum is the Yahoo Mach1MAch2CNC forum.   The thread is named "Homing Problem"

    http://groups.yahoo.com/group/mach1mach2cnc/message/97299
Regards,
Ray L.

Offline Chaoticone

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Re: Homing Probem
« Reply #8 on: August 24, 2008, 10:10:20 PM »
Post your xml as Hood asked please. Also, did you enter a value in your debounce?

Brett
« Last Edit: August 24, 2008, 10:12:49 PM by Chaoticone »
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Homing Probem
« Reply #9 on: August 25, 2008, 12:21:13 AM »
I did set 2000 for debounce, but only had to home the machine once today, so I can't say it made a difference.  I'll post the XML tomorrow. 
The important thing to remember is - Once it's in this state, *nothing* I do gets it going again, except re-starting Mach3.  It can't be switch bouncing, because nothing is moving, and, again, re-starting Mach3 gets it working perfectly again, without touching the hardware in any way.  Also, this morning, I turned on the computer, loaded Mach3, and it came up with a "Driver Watchdog Timeout" on startup.  I exited, re-started, and it did it again.  What can cause a driver watchdog timeout?

Regards,
Ray L.
Regards,
Ray L.