Some users are aware that one can specify the wavescan sample acquisition scan direction (low to high or high to low) by changing the polarity of the "backlash size" parameter in the MOTORS.DAT file as seen here on line 7:
"SP1" "SP2" "SP3" "SP4" "SP5" "X" "Y" "Z" "motor labels"
22105 21938 22358 22358 22236 -25050 -39282 -991 "low limit spect/stage motors"
83812 84010 84103 83738 84100 25309 42397 717 "high limit spect/stage motors hilim"
742571.6 742571.6 742571.6 742571.6 742571.6 7430.5938 7430.5938 7430.7438 "unit to steps conversion"
4.0267E-5 4.0267E-5 4.0267E-5 4.0267E-5 4.0267E-5 1.0 1.0 1.0 "unit to LiF angstrom or micron conversion"
10 10 10 10 10 20 20 20 "completion step tolerance for motors"
-400 -400 -400 -400 -400 400 400 400 "backlash size, (hilimit - lolimit)/backlash size"
200 200 200 200 200 200 200 200 "derivative gain"
750 750 750 750 750 700 700 700 "integral gain"
700 700 700 700 700 700 700 700 "integration limit"
2000 2000 2000 2000 2000 2000 2000 2000 "following error"
20 20 20 20 20 20 20 20 "acceleration"
200000 200000 200000 200000 200000 200000 200000 200000 "velocity"
600 600 600 600 600 700 700 700 "gain"
11 11 11 11 11 11 11 11 "hard limit mode (low xor high xor smooth)"
1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 "joystick sensitivity"
1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 "joystick acceleration"
.002 .002 .002 .002 .002 .002 .002 .002 "backlash tolerance"
78000 78000 78000 78000 78000 0 0 0 "park positions"
0 0 0 0 0 0 0 0 "Jeol velocities"
0 0 0 0 0 0 0 0 "Jeol backlash"
3000 3000 3000 3000 3000 5000 5000 50 "SX100 Velocities"
5 5 5 5 5 50 50 10 "Sx100 minimum speeds"
0 0 0 0 0 0 0 0 "unused"
Basically a negative backlash size number means to scan from low to high, while a positive backlash size parameter means to scan from high to low.
Note that some very early Cameca SX100 instruments can *only* scan ftrom low to high, so those instruments *must* specify negative "backlash size" parameters for the spectrometers in the MOTORS.DAT file as seen above.
We've only run across one instrument so far with this scan direction limitation and that is the instrument formally at Sandia National Labs and now at the University of Oklahoma.
See the scan direction poll at the top of this topic...