Hello All,

Have been fighting this problem on a MV55. Machine has work ok for past couple of years. All of a sudden the unit not homing on Y axis. We check wiring and switch, they are ok. Check Diagnostic 0033 and 3rd bit from left show 0 with the switch close. We can press the limit switch and will get a OT220+ but no change in the bit. At first we though that the i/o card is bad, change it but still the same result. Disconnected the cable from I/O to motherboard. Get All axis overtravel alarm, so at least it tell me the motherboard can see the limit switch. Question, if motherboard can read the limit switch why is there no change in 3rd bit from left of 0033? Is there some mapping of the bits withing the Fanuc 6mB?

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