Fanuc 410 'excess' error mystery, not usual suspects

[Barbapapa]

An axis in my machine throws up this error, you would think it's mechanical but the mystery deepens as things are ruled out. It's done this before but mysteriously was fine after sending the servo drive to be repaired and reinstalling it because it checked good. Now it's happening again.

When moving the X axis with the handwheel or jog, it will move a little and then stop which causes the 410 or 411 "servo alarm: X axis excess error".
When in rapid it will move much more but sounds very loud and coarse.
So it sounds like it must be mechanical drag or a motor or encoder.

If I swap the X and Y motor leads and encoder (at the servo drive), the other axis then is the one that behaves the same way while the original axis is now slooth so that rules out mechanical drag and motors.

At that point I sent the Fanuc drive out but it checked out OK. When I put it back in everything worked fine.

Now it's happening again, does anyone have any ideas?


BTW, the machine is an Excel VMC with Fanuc 21mb control. The Servo drive is an A06B-6080-H304

When the error pops up, there is no error code on the servo drive and the reset button will restore it immediately.

Thank you

[Barbapapa]

Well, I can isolate it to one channel in the Fanuc unit and can't think of anything else beside sending it out for repair and hoping something is found.

[memoryman]

why can't it be in the control? I am thinking encoder and axis control circuitry.

[Barbapapa]

Originally Posted by memoryman why can't it be in the control? I am thinking encoder and axis control circuitry.

When I switched the connectors from the control (and left motor and encoder connections in place), it then showed the other axis as the problem on the CRT.
I *think* that ruled out the control.

[memoryman]

did not realise you had tried that. I agree, that ruled out the control.
Excess error has usually means that the control did not detect sufficient movement (given the values in parameters). Sounds like the servo drive is intermittent.