Ruida 6445: 0-0 is possible, then nothing more

Ruida controller always seek home switches in the negative direction. The corner where the switches are will be (0,0) after homing succeeds, with the coordinates increasing away from the switches in whatever direction that may be.

We crawled through the process a while ago and I wrote it up so I could find it again:

The position of the home switches determines the coordinate system layout: there are no other choices.