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Mach3 pausing during move
« on: June 29, 2008, 01:04:03 PM »
When Mach3 is running it will some times pause for a second. It is more noticeable during a rapid move as it will some times trip the over current protection in my servo drives as they try to come to a dead stop at 200 IPM and then resume acceleration within a split second. I have watched the Mach3 read out while it does this and it seems to stop for a split second then start. So i am pretty sure Mach or the Pc is the culprit. Any ideas?

Offline jimpinder

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Re: Mach3 pausing during move
« Reply #1 on: June 29, 2008, 01:29:51 PM »
You are over-running your motors - nothing can come to a dead stop from 200 ipm - you are talking a lot of momentum, unles you are moving feathers.

Try cutting you acceleration down quite drastically - to say 1/10 of what it is. This should cut out your problem.  If it still persists then you will have to cut your speed.

Build the acceleration back up  until the fault re-appears, then back it off again until it becomes reliable.
Not me driving the engine - I'm better looking.
Re: Mach3 pausing during move
« Reply #2 on: June 29, 2008, 03:32:20 PM »
You would be surprised how quick a DC or AC servo will start and stop when told to do so.

It sounds more like a Windows process interfering with Mach to me.

Darek
Re: Mach3 pausing during move
« Reply #3 on: July 12, 2008, 10:31:59 PM »
I had the same thing happen to me on my old computer.  It actually stopped for about a minute.
It seemed as if the whole computer locked up.  I took the chance of just waiting, and it paid off. 
It didn't happen often, but it happened about 3 times over a 6 month period.
Now that I have the new computer with faster processor and bigger memory, my problem went away.

Basically with the new computer, I have had zero problems.
Re: Mach3 pausing during move
« Reply #4 on: September 04, 2008, 08:35:14 PM »
Thanks jimpinder

I can read the commanded and actual position counts in a software scope tool that came with my drives. It was easy to see that the commanded counts where in fact out running the actual position over time. After retuning all my drives I have it running nearly perfect and a lot faster.  ;)     
Re: Mach3 pausing during move
« Reply #5 on: September 05, 2008, 12:36:22 PM »
Quote
I can read the commanded and actual position counts in a software scope tool that came with my drives. It was easy to see that the commanded counts where in fact out running the actual position over time.

Sounds interesting tell us more.

I do have the same problem but only occasionally i haven't had a problem losing position, it acts like i have put in a random pause, and it does only happen on rapids.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Mach3 pausing during move
« Reply #6 on: September 05, 2008, 05:46:29 PM »
Well I also took the advice from HillBilly and made sure no unnecessary processes where running. I would suggest if you are having the same intermittent problem to do the same and to reduce your acceleration and velocity a tad in Mach.
    I have Copley "Acellus" drives and they have a nice little software tool to fine tune and monitor the drive parameters. You can setup the software scope to monitor the commanded position on one channel and then setup another channel as the actual position count "encoder count". Then I set Mach to run back and forth the entire length of the table at rapid speed. On the scope I could easily see the difference of the commanded and the actual position. It was basically out running the drive like was said before. So I adjusted the acceleration and velocity in Mach to match the drive and the jerk went away. At this point it was well below what I had hoped or calculated as a top speed. So I then decided to fine tune all the drive loops to get the maximum rpm at an acceptable velocity. After fine tuning the drives I bumped up Mach till I started to see the commanded and actual position start to deviate. I then backed it off a tad and called it good at about 50 ipm faster than when I had originally started. On this mill 200 IPM was the goal and now I have it without the jerk.
One thing I also noted was when Mach was out running the drive on a linear move it will decelerate quicker than it accelerates from a rapid. I think this is do to the drive trying to "catch up" to the commanded position and then drops off suddenly when the commanded position stops. I suppose if there was a feed back to the commanded system like a full closed loop system this could be taken care of dynamically. But would I now have such finely tuned drives?  ;D