Motor drive or encoder fault

[velezl]

We are having a problem with a Bosch HSL wraper machine. The problem is that there are two servo motors that work together and they are controlled by a rexroth indra drive and a plc alen bradley 5000. So here is the situation, they work fine if you run the machine on slow speed but if you raise the speed the machine stop due to a motor position error. We verify the gears for both motor, the encoder wires, the motor itself and everything looks normal. If you have any advise i will apreciated.

 

[Ken9876]

No expert here but, on one of our systems the control system vendor had to reroute the cable for the encoder as the motor was causing interference

 

[realolman]

When you say servo motor do you mean stepper motors that include an encoder?

Is the encoder an integral part of the motor, or is it somewhere else in a gear train?

The motor position error... what exactly does that mean? Does that mean the motor is in a position that is not where it is supposed to be? If so, does it go too far, or not far enough... you might be able to see where it is and where it's supposed to be in the Control Logix 5000 ladder logic. Or does the error mean that the encoder signal has been lost or interrupted?

Two motors... does each one have a drive of some sort? I am not familiar with the rexroth indra drive you mentioned.

Are there brakes involved to stop or hold the machine members ?

Sorry... I only have questions at this point.

 

[zbang]

I had a similar problem a fair while ago on some printing equipment. Wads of paper lint had gotten into the encoders and were pulled into the light path at higher speeds. Cleaned everything and it was fine. If the encoders aren't sealed units, blow the dust out and try again.

 

[petersonra]

One of the trip points on CLX motion control is how far away from the commanded position the axis actually is. If the loop is poorly tuned it may not respond well enough to stay inside the deadband that is set up.

There are several answers to this problem. One is to retune the loop(s) so they respond better. The other is to open up the deadband. I would start by opening up the deadband and see if the alarm goes away.

It is also possible that there is not enough motor torque available at the higher speed for the axis to actually get to the position it is supposed to be at when it is supposed to be there.

 

[mike_kilroy]

I think too u shud tell us if this system used to work and now faults or if it is a new system and it has never worked at high speed yet. if it used to work and now does not, did u do something to change something? often times it is the last thing we did that causes a problem to a system that used to work. also do u need the PE to be so close or can u simply open it up some and continue on?