How to Set the Reference Position in FANUC

When a FANUC system uses an absolute encoder, failure to replace the battery promptly after a low-battery warning may result in the loss of the reference position, requiring the reference position to be reset.

How to Distinguish Between Absolute and Incremental Position Encoders?

1. Check whether the encoder model number contains the letter “I” or “A”:

I indicates incremental;
A indicates absolute.

1. All βi-series motors are equipped with absolute encoders.
2. An absolute position encoder can be used in place of an incremental position encoder.

Reference Position Setting Procedure

Manually move the machine to the desired reference position. Set parameter No. 1815, bit 4 = 1, then power the machine OFF and back ON. The current position will be established as the reference position.

If parameter No. 1815, bit 4 cannot be set to 1:

1. Rotate the motor by at least one full revolution.
2. Set the parameters in the following sequence:
   1815#5 = 0 → 1815#4 = 1 → 1815#5 = 1, then power the machine OFF and back ON.

When an absolute position detector is used, this parameter must be set to 0 during initial setup or after replacing the absolute position detector. After cycling the power, establish the reference position of the absolute position detector by performing a manual reference position return or a similar operation. This establishes the positional correspondence between the machine position and the absolute position detector, after which this parameter is automatically set to 1.

Possible Causes of Reference Position Setting Failure

1. Rotate the motor by approximately one full revolution, and then set the reference position again.
2. Check whether the encoder cable has a 6 V power supply wire and whether the cable is damaged.
3. The encoder may be faulty.

How to Set the Reference Position in Mitsubishi

1. In [Axis Select], enter the displayed axis name, or select [Next Axis] / [Prev Axis].
2. Set the required parameters.
3. Select the machine operation switch mode: [Manual] or [JOG].
4. Set [Absolute posn set] to 1.
5. Set [Origin-P].
6. Move the machine to the reference position and adjust the reference point.
7. Set [Origin-P] to 1.
8. When [Status] displays [Completed], the absolute position has been established.
9. Turn the NC power OFF and back ON.