This reads like but doesn't look like the D80 DRO. Trying to read and follow the manual is just impractical. Here's what works for me, assuming similar functions.
Set up the distance you want to calibrate at and zero the desired axis.
Select the C function key. Move the cursor to the appropriate axis. Press enter to select.
The display will now show L1, L and S
Move the carriage or cross slide to cover the calibration distance
Move the cursor to L, I forget whether you need to hit enter to select this field. Try both ways.
On my screen, a softkey marked "input" pops up. Press that, input the actual distance, since the field contains what the DRO thinks it did. Press enter.
That updates the scale factor. On my DRO there is also an exit button. Press that to update scale factor and leave.
The DRO display will now show the actual distance you told it.
Or something like this.
