Re: [CAD_CAM_EDM_DRO] Caliper to PC interface, Part II: Data Format ?????? Help ?

Graham Hollis wrote:

> The fact that the same display value is outputting different values is a
> problem hard to understand. It may be that the caliper has some logic to
> average the data to remove the hysterics.
> I agree with your theory that there are two sets or readings, relative and
> absolute.
> The closest I came with the data available was that that there are two 10
> bit counters starting at offset 3 and 13 with the first counter the integer
> and the second the fraction. Each count could be .0005 which may be the
> resolution of the device. So the counters may be:
>
> .000 - 00..0000
> .0005 - 00..0001
> .001 - 00..0010
> .0015 - 00..0011
> .002 - 00..0100
>
> The negative does appear to be a 2's compliment of the counters.
> The theory seems breaks down at higher values though so the 10 bit counters
> may be several fields of data.

Of COURSE! Now I know why you are having trouble! Switch the caliper
to metric, then take some measurements. The basic caliper is metric, and
converts to imperial. The metric readings will correlate much better with
the data stream. Once you understand the metric readout format, I think
it will be possible to figure out how the imperial readout works. The
intrinsic
resolution of the unit is probably higher than the readout, otherwise there
would
be settings that could not be obtained in the inch mode. As they all seem
to be able to get to all possible inch readings (if you're patient enough)
there must be a higher internal resolution.

Jon