physical axis fault with mo2ae motion card

B

Thread Starter

bryan

axis fault is noise feedback error, not sure if it bad encoder or noise generated thru the encoder cable any ideas how I might troubleshoot this?
 
If it happens intermittently I would suspect noise on the encoder cable or possible loose connections. If this is the case I would check all wiring practices, shielding, motor, encoder etc. To verify everything is shielded and landed properly. Wiring practices are generally the number 1 problem for feedback noise... is this a new machine or has it been in service for a while?

If the axis can not run at all I would replace the motor/encoder... but it could be a broken encoder lead... likely this isn't the case since you didn't mention getting encoder lose... rather you said encoder noise.

As far as trouble shooting, I would hook an o-scope up to the encoder signals... but reality is the axis card is already telling you that you have noise...
 
R
I had a similar problem with a 1756-M03SE system using Ultra3000 drives; occasional faults that came and went. Eventually I could not clear the fault even with a power down and investigated the motor itself. I checked all the connectors and reinserted them.

Apparently the encoder connector had some dirt on the contacts from the initial installation. When I reconnected the encoder, all faults were cleared and I have not had a problem since (6 weeks so far).

It was a simple solution but sometimes they are the correct ones. It took about 2 weeks of operation 24/7 to convince me that the connection was the problem; I simply could not believe the connector could be the root cause. Apparently, since the voltage and current that is used in encoders is quite low, a bit of oxidation or a few grains of dirt could be all it takes to cause problems.

Regards,
Russ Kinner
SSOE, Inc.
Phoenix, AZ
 
J
I am an Applications Engineer for an encoder company. One uncommon and difficult to find source of encoder noise can come from an earth ground point at a factory or plant that is assumed clean, but is not.

An indication of this is if you remove the earth ground connection to the encoder or motor and the system performance improves.

Too small of wire gauge over long cables runs can be a problem as well.

If it's possible in the application, and ok'd by the manufacturer, the use of a termination resistor on the encoder channels often helps to compensate for noise.

Jim Miller
Quantum Devices Inc
jmiller at quantumdev. com
www.quantumdev.com
 
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