Ok folks,

Here we are again back at the same X=25 problem but with new information.

I am having a problem with my system. No matter what I type in for a distance, the servo goes nuts and always ends up at a place its not supposed to be.
It used to be that when I typed in !feedrate 10:machgo 2 the servo would spin a high rpm's and always end up at X=25.xxxx. (obviously a problem)

Its doing it again now that I have my galil card back from repair. No matter what I type in, it goes to x=25.xxxx.

I went into my motion settings in the setup.exe and changed the motion settings to the following:
RATIO 1 = 10000
GEAR 1 = 1

Now if my understanding is correct, this will make my system think that 1 inch = 10,000 encoder counts. Right??????????

But when I tell it to go 1 inch, the readout displays 3.2XX inches and the encoder counts read 32XXX. Now with my motion settings as above, 32000 encoder counts would equal 3.2 inches.. And it shows up that way. HOWEVER, I can see the motor spinning and its rotating at around 500RPM and I know its going allot farther than 1 inch. (more like 50 yards) One motor revolution by hand will produce 1024 encoder counts.
If I disable the motor and turn the shaft by hand one full rotation CW, I get exactly 1024 encoder counts. Rotate it CCW one full rotation and it goes back to zero. Seems ok ya? NOT.

Give the motor a command and it now goes to 3.2xxx every time. (it doesn't matter how fast, how far, or which direction I tell it to go, it only goes one direction and always to the same spot.

I hooked up my "test servo board" and it works perfectly.. This would lead me to believe I have a problem with my drive.. BUT, there is a big difference between them in that my test servo is 110volts and my problem drive is a 3 phase 480volt unit that is being run by a rotary phase converter.

Here are some more symptoms.. When I power up the drive, it takes off at high RPM then comes to sudden stop. The enable circuit is jumped at the moment for troubleshooting.

Anyone ever hear of a bad drive doing these kinds of things? This drive has all kinds of error codes it can produce but the only one I have ever seen was an "RB" which means resolver break when it got disconnected once.

I'm stumped and at my wits end with this..

Any ideas?

Murphy

Regardless of what you think of the problem I posted I have another question pertaining to what may be the same problem.


Could a cheap "computer store" type of battery backup cause a common to float?

In other words.. If my computer was the only thing in my control panel that was being run from a batter backup could this cause a ground or common to float and create problems? The battery backup unit does get powered by the 3 phase system by way of a stepdown filtered transformer supply.....

Thanks.

You need to test your drive stand alone with a battery command signal. See if you can make the drive go either direction with the battery. If you can make the drive go both directions with the battery and the test servo works in both directions then something is biasing the command at the drive.

NOTE:
I am working on a A-B drive and it appears to be like your diagram showed. The rectified line AC is used on the primary of a transformer in switch mode fashion to form the lower voltage isolated DC supplies. A-B does recommend when using it single phase to hook to L2 and L3 on the drive. After looking the board over I see no reason why other than they make larger models with fans and these fans must be on L2 and L3.

Darek

Here are some more symptoms.. When I power up the drive, it takes off at high RPM then comes to sudden stop. The enable circuit is jumped at the moment for troubleshooting.

On this one it should be easy to find out if it is the case of a condition when the drive powers up with the enable pin already active.
Disconnect the analogue input and jumper the analogue input to common, so the input is definately zero, and now power up the drive, if it takes off as before, then this is a natural condition of the drive powering up in the enabled state.
Al

On this one it should be easy to find out if it is the case of a condition when the drive powers up with the enable pin already active.
Disconnect the analogue input and jumper the analogue input to common, so the input is definately zero, and now power up the drive, if it takes off as before, then this is a natural condition of the drive powering up in the enabled state.
Al

AL,
I think I mis-lead you.. I am not powering up the drive with the enable because that should never happen in "real operation"..
What I should have said is that I apply power to the drive, it goes threw self test and says "RDY". (ready).
I connect the jumper to the enable and it takes off at high rpm's for about 2 seconds then comes to a complete stop. (When I say complete stop I mean it stops completely OR stops at a level were the VCS bias offset can take care of the small amount of rotation.
(which brings up another point) It seems that every time I turn the drive on and off, I have to readjust the VCS offset to get absolute zero movement..

Thanks!
Murphy

You need to test your drive stand alone with a battery command signal. See if you can make the drive go either direction with the battery. If you can make the drive go both directions with the battery and the test servo works in both directions then something is biasing the command at the drive.

NOTE:
I am working on a A-B drive and it appears to be like your diagram showed. The rectified line AC is used on the primary of a transformer in switch mode fashion to form the lower voltage isolated DC supplies. A-B does recommend when using it single phase to hook to L2 and L3 on the drive. After looking the board over I see no reason why other than they make larger models with fans and these fans must be on L2 and L3.

Darek

Darek,
I have a small regulated power supply that I was using.. Its able to put out 0-18vdc.
The drive works fine when using this power supply to send VCS signal to the motor. I can speed it up, slow it down, and if I reverse the leads, I can make it go backwards the same way.

Are Allen Bradley drives specialized like Fanuc or can they be adapted to different motors and differnet setups? I was told to stay away from Fanuc and am wondering who else I should stay away from.

:banana: I FIXED IT!!!!!!!!!!!!!!!!! :banana:
My servo VCS terminals are INVERTED , NONINVERTED, 0 VOLTS

My ICM2900 VCS terminals are MOCMDX, GRND


MOCMDX and GRND go to the INVERTED and NON-INVERTED terminals and it makes a BIG difference which is which....

Control Techniques said it would not matter.. (chair)
They said it would just make it run backwards.

Ya right...
Problem solved...... CNCZone.com rules!!!!!

Without the help I got here, I would have been hunting this problem until I was an old man....

Thanks for your replies.. :cheers:

Your symtoms are pointing to a amplifier thats command input needs to be an isolated signal (Or the isolation in the drive is faulty.).

The A-B drive I am working on might as well be Mitsubishi every semiconducter in it is theres.

Darek

I posted before I read your post. That is great!

Your symtoms are pointing to a amplifier thats command input needs to be an isolated signal (Or the isolation in the drive is faulty.).

The A-B drive I am working on might as well be Mitsubishi every semiconducter in it is theres.

Darek

I posted before I read your post. That is great!

Ya.. Isolation, non-isolated, inverted, non-inverted..bla bla bla..
I can read a silly schematic.. I wish they would provide them but after quoting me $810 for fixing the drive and $250 just to inspect it, I know why they wont provide those schematics. Bas_ards..

I watched a movie called Armageddon with Bruce Wills.. At one point, they are arguing how to fix the spacecraft. The American says "Your Russian, you don't know the American Components" to which the Russian guy says "Russian components, American Components, All made in Taiwan!!"

LOL

Thanks for your help
Murphy