Measurement Computing DBK70 - Manual (Page 107)

Appendix B 937696 Scale & Offset in Summary View B-3
Calculating Output Scale and Offset Values for Analog Output Signals
Example 1
Calculate Output Scale and Offset for an analog output signal with a signal range 0 to 5 VDC being
equivalent to an RPM range of 0 to 10,000 RPM, where the resolution of the received data is 0.25 RPM/bit
and has a range of 0 to 16082 RPM. (i.e., V
H
= 5,000,000 µVDC, V
L
= 0, D
H
= 10,000, RPM, D
L
= 0 RPM,
R = 0.25 RPM/bit, S
L
=0, and S
H
=16082):
Output Scale = [(V
H
- V
L
) / (D
H
– D
L
)] * R
= [(5,000,000 – 0) / (10,000 – 0)] * 0.25
= [5,000,000 / 10,000] * 0.25
= 500 * 0.25
= 125
Output Offset = [(S
L
-D
L
) / R] * Output Scale
= (0 - 0 / 0.25) * 125
= 0
Example 2
Create a full range analog output signal (i.e., 0 to 5 VDC) equivalent to a temperature range of
-50
°F to +250 °F, where the data received from the vehicle data bus has a resolution of 0.125 °F /bit and
has a range of -300 °F to 300 °F (i.e., V
H
= 5,000,000 µVDC, V
L
= 0, D
H
= +300 °F, D
L
= -300 °F,
and R = 0.125 °F/bit
Output Scale = [(V
H
- V
L
) / (D
H
– D
L
)] * R
= [(5,000,000 – 0) / (+250 – (-50))] * 0.125
= [5,000,000/300] * 0.125
= 16666.6667 * 0.125
= 2083.3333
Output Offset = [(S
L
-D
L
) / R] * Output Scale
= [(-300)-(-50)]/(0.125)] * 2083.3333
= -250/.125 * 2083.3333
= -2000 * 2083.3333
= -4166667