PLATINUM Series Controllers User’s Guide
30
Reference Section: Initialization Mode (INIt)
6.1.4.3
Bridge (Ratiometric) Input Scaling
To calibrate to a specific bridge device, the user must provide two known loads and enter the
corresponding values. This allows the device to calculate a straight line correction:
Weight = Input Reading X Gain + Offset
Scaling operations allow translating source (input) signals to scaled output signal using a linear
translation defined by a SLOPE (or gain) and an OFFSET. As shown below, (X1, Y1) and (X2, Y2) define
two points on a line that has a certain SLOPE and OFFSET. Knowing the SLOPE and OFFSET allows
determining the OUTPUT value for any given INPUT value using the equation:
Output = Input X SLOPE + OFFSET, where
GAIN = (Y2 - Y1) / (X2 - X1)
OFFSET = Y1 - (GAIN * X1).
The Input reading is expressed in terms of full scale, which is directly dependent on the applied
reference voltage which is in turn derived from the excitation voltage. Due to the ratiometric design the
absolute value of the Excitation voltage and exact resistor values do not enter into the weight
calculation.
If (X2 - X1) == 0, the GAIN is set to 1 and the OFFSET is set to 0.
X
X
