Loadstar Sensors DQ-1000A Frequency to Analog Interface - Manual (Page 2)

Pre-Calibrated DQ-1000A
If you have received a DQ-1000A pre-calibrated to a load cell, please refer to the
calibration sheet indicating the lb/volt (or kg/volt) on how to compute the load from the
measured voltage. For example, in the graph shown below for a 2000 lb load cell, if the
voltage measured between pins 6 and 7 is 3.0 V, then
Load, L = (3.0 * 509.81) – 223.96 = 1305.47 lb.
Depending on your setup, the voltage at zero load may be different from the one when
the load cell was calibrated – for example, if you are calibrating in tension, your preload
from fixtures etc may be different. If you have a preload that needs to be zeroed out,
simply take the difference in voltages, and multiply by the slope (in this case 509.81).
For example, with a preload (to be zeroed out), if the measured voltage is 0.8 V, and
with an unknown load L1, the measured voltage is 2.0 V, then
L1 = (2.0-0.8)*509.81 = 1.2*509.81 = 611.78 lb.
Sample DQ-1000A calibration graph for a 2000 lb load cell