
ZENO
®
-3200 USER MANUAL
Coastal Environmental Systems (206) 682-6048
Page 172
If your sensor output is linear
192
, then coefficient A is always zero.
In the case of linear sensor, to calculate B and C, you need to know the following values:
The output voltage range of the sensor, v
min
to v
max
.
The corresponding range in engineering units, x
min
to x
max
.
The slope B is given by the equation:
The offset C is given by the equation:
As an example, a sensor voltage range is 0 to 2.5 VDC and it represents the linear range of 0 to 355
degrees in engineering units. To determine the coefficients B and C, you will obtain the following:
The above example gives B=142 and C=0, and the A/D converter input range is -0.512 VDC to +0.512
VDC.
If your sensor output is nonlinear, coefficient A will not be zero.
Nonlinear sensor outputs are not necessarily parabolic
193
, but the quadratic
equation may approximate the desired, scaled readings within a limited
range.
If your nonlinear sensor output cannot be accurately scaled using the
quadratic equation, then use one or more Processes (refer to Section 10.4) to
create the scaled value.
192
Linear means that for any sensor voltage change, the equivalent value in engineering units changes
proportionally the same amount.
193
Parabolic means that as the sensor voltage changes, the change in scaled units changes proportionally to the
square of the sensor voltage.
0
05.2
03555.20
142
05.2
0355
3550
5.20
maxmin
maxmin
C
B
xx
vv
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