Won't hold revolution counter update

    Hello everyone, Hopefully you can help me. I've got an ABB IRB 6400 that I'm having issues with updating the rev. counters. I can jog the it to align all of the calibration marks, and it lets me update, but when I jog it away from the calibration point, and back again, the marks are no longer aligned. All axis are about 1 hash mark off. I have tried a new SMB unit, and a new battery pack on the unit, as that's usually the issue we encounter, but it still does the same thing. I even tried aligning the marks offset, to accommodate for this, but then it goes to the exact point where I updated it, instead of offsetting it. Can any of you give me any tips as to what else could be going on? Thanks in advance. :wallbash:

    Sounds like the calibration may be off a little. You could try a FINE CAL - (write down the calibration offsets first).
    I usually have a ZERO program that is essentially a " MoveAbsJ [[0,0,0,0,0,0],9E+09,9E+09,9E+09,9E+09,9E+09,9E+09]]\NoEOffs,v300,fine,tool0;" After a rev counter update, I run ZERO - a few axes will twitch a little, but should stay close to the mark.

    Iowan's answer and solution should fix the problem. Possible causes the Fine Calibration could be off: If someone has reloaded software but did not reload the MOC parameters that contains the Fine Calibration data. Look at the motor calibration parameters for each motor (IRB) and see if the cal offset numbers are all zeros. Another scenario is someone did a fine calibration at one time when the robot was out of position and then the robot was moved to marks and the rev. counters updated. Also have seen where fine calibration is off where a backup from another robot was used and now the offsets of a different robot are loaded. Any axis where the motor has never been removed should be able to use the fine calibration numbers on the back of the lower arm. Be aware the numbers are in radians so a revolution is represented by a number between 0 & 6.28319 (2*pi).

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