X axis not working correctly

[edeeec]

I have taken some readings with my chinese caliper connected as previously discussed and reading the x channel from P2.0 P2.5. The scale and display match perfectly when connected to P2.1 and P2.4.
Scale moved to the left to a stop and zero set. Zero set on the Android Display. Settings in mm CPI set to 20480.
Scale moved to the right and readings taken then moved back to show similar readings on the return.
Scale       Display
Reading  Reading
0.00         0.00
1.72       38.91  
3.01       37.64
4.84       35.78
6.49       34.14
11.16     34.55
18.58     -18.58
21.62     -21.54
26.84     -26.78
38.33     -38.34
52.97      28.46
47.14     -37.00
40.63     -40.64
1.70       38.93
16.56     -15.92
18.61     -18.62

Can it be that the scale is 24 bit but interpreted as 21 bit or Bin6 or some combination of these?
Richard