Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: CharliePatten on March 24, 2010, 10:00:16 AM
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I have one switch located on each of the X-, Y+, and Z+ end of axes travels, and have the X HOME, X--, Y HOME, Y++, and Z HOME, Z++ inputs enabled. The problem is the RESET LED after 3 - 4 seconds keeps flashing, even after hitting RESET again. The only way I can prevent this from happening is to disable X--, Y++, and Z++ limits. Can anyone assist me in solving this problem?
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Sounds like electrical noise, try setting the debounce interval to 2000 and see if that helps. If it does then it proves its noise so you would be better fixing it by properly shielding and grounding the shields.
Hood
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I have the debounce set at 2000. All cables (motor and limit) are shielded and grounded to chassis grd. at one end. I have even seperated motor and limit cables so they don't run in the same raceway. What is weird is I don't have the problem when only the "HOME" inputs are enabled! It only happens when I enable the limit switch inputs.
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Can you home ok if you have the limits disabled?
Hood
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Yes.
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can you attach your xml please.
Hood
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I have copied it on to a flash drive. How do I attach it to this post?
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You will need to rename it to something like CharliePatten.xml as the forum will only accept a file name once. To attach you use the additional options button on the reply page and browse to your xml.
Hood
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Hope this works!
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Dont see anything wrong in your xml apart from you have enhanced pulsing disabled.
How are your switches wired?
Hood
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I have one switch on the end of each axis which is enabled as a homing switch. They are each wired in to individual inputs on my breakout board. When I enable them as limits, that's when I have the problem. I also am having difficulty setting up the soft limits.
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You can only use them as Limits for one end of the axis, ie either X++ OR X-- depending on which end they are at. Unless that is the switch is in the middle and the trigger is either end.
That however should not be your problem as it would just mean they wouldnt activate properly if set up as both X++ AND X--.
When you enable them do you see the LED on the diagnostics page light?
Softlimits should be easy, X min Y min and Z Max will be zero, X Max, Y Max will be your travel and Z Min will be your travel but a negative value. If your home switches are at the wrong end of the table from machine coords zero then you also need to enter a Home Off value equal to the distance of the travel.
Hood
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When I enable The X--, Y++, and Z++ limits, along with the "home" LEDs, both the "home" and "limit" LEDs do light up on the diagnostics page. That is when the problem of the RESET button starts flashing! It happens randomly and I also noticed that the limit and homing LEDs flash quickly just before the RESET flashes. It is almost like enabeling the limits is causing the "noise" that trips the RESET. This dosen't make sense because the wiring and switches are all the same and the RESET dosen't trip when only the home switches are enabled.
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When you have enabled only home switches Mach will not go into reset if they become active as they are just home switches and not limits. That was why I asked if you could home correctly as I was thinking you had noise problems or bouncy contacts. If that was the case your homing would not work properly all the time as the switch would be seen before the axis actually got to it.
It still sounds however like it is your problem and it is just luck that when you home the switch is not being seen whilst doing so, easy way to test is remove the switches from the BOB and connect a wire in their place and enable the limits and home switches and see if you still have the issue, if you dont then you know the problem is in the switches or the switch wiring. If you do then its from the BOB upwards to computer.
Hood
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Hood:
Not sure you got my last post? I now have a different problem. Neither my Y or Z axis moves either using the MPG or trying to do a homing move. The DRO's do index. I haven't changed any settings, however I can't continue to troubleshoot my previous problem until I solve this one. I have attached the most current XML file.
Thanks,
Charlie
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The DRO's do index.
What do you mean by that?
Hood
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Just looked at your xml, you have the MPG set to multi step mode and the step increment of 0.001 so you may not see it move much unless you wind the MPG quite a bit.
Hood
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Changing this has no effect on the problem! The X axis still works fine with the MPG. It sounds like you are running out of suggestions! I do greatly appreciate all your help on this. Thank you. I will keep plugging away.
Regards,
Charlie
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Can you jog these axis from keyboard or tab page? Do you see the Y and Z Dros change when jogging either with MPG or Keyboard?
Hood
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Only the X axis jogs with either the MPG, Tab page, or keyboard. The DROs do indicate movement on all 3 axis.
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Then I would say hardware is more likely to be at fault. Change the active state of your E-Stop and remove your port cable and test with a voltmeter directly on the parallel port pins.
Hood
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Thanks Hood. I have located a faulty 25 cond. ribbon cable inside my control enclosure as the cause of the latest problem. Now that I have fixed that, I can get back to solving the previous problem.
Regards,
Charlie
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Thats good to hear Charlie. I still think your limit problem is hardware related as well as I think you said you get the Home LED occasionally flashing. If you can try like I suggested and connect a wire directly to your bob in place of the limit switches and see if the problem is still there even when you enable limits.
Hood
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Hood:
I have finally located the source of the "noise" that was triggering my "reset" button, however the answer needs an explanation! I have all my limit switch (shielded) cables grounded on the limit switch end only. When I remove the ground wire, everything works normally with no triggering of the "reset" button. This is just the opposite of what you would expect. I have tested this both ways over an 8 hour period and feel confident that this was the problem. Any thoughts?
Charlie
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Sounds like your ground point may not be a ground?
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Logical conclusion! I will look into that. Thanks.