1394 axis faults

hey guys, got a question, hopefully someone has an answer. We have an AB 1394 drive that is giving us and axis fault. The fault comes up as a position tolerance error fault. This fault comes back repeatedly, my question is, what do I do about it. According to the manual, this doesn't necessarily mean that the motor or encoder is faulty, just that something may be jammed up. We have not tried anything yet, but I am wondering if I retuned the motor if that would help at all. Just looking for any suggestions on which way to go with this to try and find the root of the problem. Thanks in advance.

Russ

1394

Russrmartin,

I used to work with some 1394's, they were easy to program but very frequently resulted in parts swapping to troubleshoot. The two biggest things that I have seen cause the position error fault was some type of a mechanical bind or a problem with the dynamic braking module. We had blown fuses in our braking modules on a couple of occasions. If you have any room to play you may be able to open up your tolerences some. Retuning your motor probably would not hurt but it has never helped me unless a new motor was installed. One other thing, check the grounding of the resolver or encoder and their cable. The most comman cause by far in my experience was a mechanical bind. It doesn't take much of a bind if the tolerences are tight.

Keith

More fault causes.

In addition to mechanical binding I would add improper tuning, and trying to accelerate or decelerate faster than what the system is phyiscally able to do. The key to determining which problem is the cause is to know exactly when the fault occurs and what the control output is during the motion profile.

It is doubtfully that a mechanical bind is speed dependent. Slow the system down and see if the bind still occurs. If fault occurs in the same place then mechanical bind is probably the problem.

Reduce the acceleration and deceleration rates. You may not be able to accelerate with a load as fast as you wish.

Reduce the speed. If this fixes the problem, the velocity feed fowards are not set right.

IT IS IMPORTANT TO KNOW WHEN IN THE MOTION PROFILE THET FAULT OCCURS.

"Reduce the acceleration and deceleration rates. You may not be able to accelerate with a load as fast as you wish."

Mechaincal bind is somewhat dependent on the speed, acceleration and deceleration. The more the bind, the more the load. As the motor runs (accel & decel) slower the motor has more power, thus possibly overcoming the binding area.

I've had this problem before and most of the time it comes down to parts wearing and friction getting higher. Without replacing the parts, I can slow the movement down and this will allow the axis to run until we fix the mechanical bind.

I've also had the encoder cable start to break and this will give you a different error.

Closure on the subject

Men,

Thank you all for your ideas and suggestions. We did find the problem, and basically we found it by going back to the old start swapping parts theories. We first swapped the axis module, which helped little. We then went for the motor and wala, the motor cable had shorted some pins on the motor, thus giving us an axis power fault. There were several pins that were toast, so I am kind of thinking that we were getting different errors according to which pin was shorted at any given time. Thanks again for all the input.

Russ