Re: chinese dro scale shorting dro display?

I don't know if this has bearing on this thread, but the digital
calipers scales usually have the metal at the V+ side of the battery.
Maybe the scales you are using are similar. In this case, you will
either have to isolate the DRO control box( via non-conductive
mounting and a wall wart type supply) to make its ground float, or
isolate the scales using something like delrin blocks.

Better DRO systems isolate the clock and data lines to avoid the
isolation req.

Hope this helps.
-Lee