Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: fam891 on October 05, 2010, 01:41:05 PM

Title: Mach3 losing steps
Post by: fam891 on October 05, 2010, 01:41:05 PM
Hi all.  We recently upgraded one of our plasma cutters to Mach3 from Mach2.  After doing so, we noticed that the x and y axes would lose steps.  In other words, if I was to zero the torch, drive around the table for a few minutes, and return to zero, the torch would be 3/16" away from zero in both directions (both negative x and negative y).  After trying to change every setting imaginable within Mach3, and swapping drives around, etc, I reinstalled Mach2.  Now the torch goes back to zero as it should.  Does anyone have any idea what would cause Mach3 to "lose" steps on the same setup that works perfectly with Mach2?

Thanks,
Frank
Title: Re: Mach3 losing steps
Post by: Hood on October 05, 2010, 03:21:15 PM
Have you got the same motor tuning, been a while since I used Mach2 but seem to remember things are a bit different regards motor tuning. Other thing to make sure is that you have the active state set correct for the motor outputs and maybe also try  a wider pulse width and Dir prechange (Motor Tuning page)


Hood
Title: Re: Mach3 losing steps
Post by: fam891 on October 05, 2010, 03:28:43 PM
Hi Hood.  Thanks for the reply.  The motor tuning for steps/unit, velocity, and acceleration is the same, except that the velocity is in units/s (Mach2) instead of units/min (Mach3).  In Mach2, I left the default settings the same for pulse width and prechange.  All works good with Mach2.  In Mach3, I tried to change the pulse widths from 1 to 5us.  The lower the number of microseconds, the worse the motors ran.  I didn't see a dir prechange setting in Mach3.  I also tried to flip the active setting on each motor and it didn't make a difference.  Any other ideas?
Title: Re: Mach3 losing steps
Post by: Hood on October 05, 2010, 03:39:15 PM
It is the Dir Pulse it calls it in Mach3.
Try a higher setting for the pulse width, possibly up to 15.
If that doesnt help then attach your xml's for both Mach2 and 3 and I will see if I can find a problem.
Hood
Title: Re: Mach3 losing steps
Post by: fam891 on October 05, 2010, 06:54:57 PM
I tried to change the Dir pulse width to 15, and then to zero.  There was no effect on the error.  I have posted the xml files for both Mach2 and Mach3.  One thing to note is that every once in a while, the start of a movement will cause the steppers to "grunt" a bit, and it sounds similar to a stalled stepper.  However, this only happens when using Mach3, and it happens randomly.  I have checked all of the mechanics of the machine, and the linear bearings and drive components all operate smoothly; not to mention that it only happens when using Mach3.

Frank
Title: Re: Mach3 losing steps
Post by: Hood on October 05, 2010, 07:07:49 PM
What are the specs of the computer?
Hood
Title: Re: Mach3 losing steps
Post by: Hood on October 05, 2010, 07:15:15 PM
Just looking through the xmls and first thing I notice is  you are using 25KHz kernel on Mach2 but you have 45KHz for Mach3. Try setting it down to 25KHz and see if that helps.
Hood
Title: Re: Mach3 losing steps
Post by: fam891 on October 05, 2010, 09:01:05 PM
I changed Mach3 to 45kHz when it was not working to see if that would help.  It was originally at 25kHz.  Changing to 45 didn't make any difference.  The computer is a dell, about 3 years old.  I don't have specifics with me as I'm not at the office anymore.  I can post them tomorrow.

Frank
Title: Re: Mach3 losing steps
Post by: Hood on October 06, 2010, 02:11:49 AM
run the driver test and see what it looks like.
Hood
Title: Re: Mach3 losing steps
Post by: fam891 on October 06, 2010, 10:32:00 AM
Hi.  Here are the results from the driver test.  I ran it all the way up to 100kHz and it worked great.  I have also attached the specs for the computer.
Title: Re: Mach3 losing steps
Post by: Hood on October 06, 2010, 10:49:41 AM
Computer should be ok although it is very low on memory for running XP, Mach3 will use a bit more resources than Mach2 so it is possible that that may an issue.

Driver test looks fine and I didnt see anything else in the xml that would cause issues.

If you have an extra stick or two of memory try and get it up to at 512Meg and see if it helps, another thing you could try is turning off the toolpath view to see if that helps but unlikely unless the files you are running are large.

What does the frequency and Time in Int say on diagnostics page and also look at the CPU usage and see what it sits at when running some code, Ctrl Alt Del then Performance will get you there.
Hood
Title: Re: Mach3 losing steps
Post by: fam891 on October 06, 2010, 01:40:25 PM
I measured the CPU and RAM usage when idle and when running.  I also posted the General Config and Diagnostics page.  I changed a few things in the Gen Conf since I posted the XML's yesterday.  I just turned off high res screens, enhanced pulsing, Plasma Mode (CV), G100 Nurbs (CV), and Home SW. Safety.  After changing all this, it still made no difference; the error is exactly the same.  I will try to get a stick of RAM at lunch and try it this afternoon.

The Time in Int fluctuates between 5.5 and 6.5.  The pulse frequency is steady at 43718.
CPU Usage:
0-12%, Mach3 running, but idle
20-50%, Mach3 running and cutting

Memory Usage:
47104k, Mach3 running, but idle
50244k, Mach3 running and cutting

Frank
Title: Re: Mach3 losing steps
Post by: Hood on October 06, 2010, 02:33:44 PM
Time in Int looks decent and although a bit low the Frequency is at least steady. If I were you I would put te kernel back to 25KHz as you dont need it on 45K so no real reason to use it.
CPU seems fine so hopefully it is just the memory that is the issue.
Hood
Title: Re: Mach3 losing steps
Post by: superagurk on August 09, 2013, 07:08:25 PM
Hi, did you get any solution on losing steps?
Title: Re: Mach3 losing steps
Post by: fam891 on August 11, 2013, 12:29:16 PM
No, I never did see a resolution to this. I switched back to using mach2 since we are just cutting out simple shapes. I'll be putting mach3 on a new computer and installing all new controls one of these days.
On occasion, we use mach3 to cut some files that mach2 won't cut. They come out ok as long as there aren't a lot of direction changes in the cut file.
Title: Re: Mach3 losing steps
Post by: Hood on August 11, 2013, 01:37:50 PM
Frank,
 when you said this
Quote
as long as there aren't a lot of direction changes in the cut file.
It made me look at your xml's again.
In Mach2 you have the Dir pins for your axes set Active Low, in Mach3 however you have them set Active High.
That could well be your problem as if your drives require the active low then you will lose a step on each Dir change.
Hood