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Datum mode
When the battery is first inserted or replaced, the MIH enters a datum mode routine which must be successfully completed prior to use. The A and B-axis position detectors within the head require datuming to a zero position before the LCD will display the correct A and B-axis positions. Datuming the head will also be required if a head datum error occurs during use.
Step 1
On entry into datum mode the LCD shows a datum error. Unlock the head to reset datum.
![MIH - datum mode - 1](/cmmsupport/knowledgebase/media/img/en/2f9a4f3f8e654d7d8a0a06007f35236f.jpg)
Step 2
Rotate the A and B-axes to their zero positions by aligning the zero position markers on both axes.
Step 3
Lock the head in this position and press the M+ and M- buttons simultaneously to reset datum.
![MIH - datum mode - 3](/cmmsupport/knowledgebase/media/img/en/a8047eb677d841a288d50259ad7907c2.jpg)
Step 4
The display will now change to show A and B-axis data at A0.0, B0.0. Datum is now set and the A and B-axis displays will show positional data when the head is locked and unlocked.
Step 5
Confirm that datum is correctly set by rotating each axis to its extreme positions and check that the position data on the LCD is correct.
A-axis 0° to +105° plus overtravel
B-axis ±180° plus overtravel.