The battery of Fanuc system of VMC850B vertical machining center produced by Baoji Machine Tool Factory is dead. How to reset the reference point when the reference point data is lost?

It can be seen from your description that the machine tool uses an absolute encoder. If the data is not lost, it is recommended to replace the battery when the system is powered on. If it has been lost, it doesn't matter.

If the reference point is set, the new system is as follows: change 18 15#4 and #5 to 0, then move the workbench to the reference point position, and finally change 18 15#4 and #5 back to 1, and power off and power on will be OK.