Rice Lake MSI-8000 RF Remote Display - ScaleCore Configuration Management Program (ScCMP) - Manual (Page 40)

36 ScCMP Operator’s Manual
8.4 DAC Calibration vs DAC Configuration
Helicopter systems with DAC output have two aspects required for DAC output. The calibration of the DAC
hardware to match the desired voltage range, and the configuration of the DAC function that relates weight to the
voltage.
The following picture shows four example configurations D1, D2, D3, D4 for DAC outputs. Each configuration
links the concept of ‘zero scale’, and ‘full scale’ to both weight values and voltage values to create a linear scale
(i.e. two points makes a line).
Figure 8-3. Example DAC Output Calibration vs. Configuration
The voltage output is a hardware calibration that tells the software what DAC count to write when it should be at
‘zero scale’ or ‘full scale’. This sets the voltage range to within the limitations of the hardware output capabilities
(i.e. 1-5V). In ScCMP, this is referred to as the DAC Calibration and it is not saved or restored with the profile
feature. It is written to the DAC and saved in the hardware itself. Only a DAC calibration operation affects these
values.
The weight output translation defines what weight value should be used to output ‘zero scale’ or ‘full scale’. This
translates 100 lbs into ‘zero scale’ and 2500 lbs into ‘full scale’ (for example). In ScCMP, this is referred to as the
DAC configuration and it is saved and restored with the profile feature.
Typical helicopter load systems are run through an ATP (Acceptance Test Procedure) that requires the testing and
calibration of the DAC output prior to shipping. DAC calibration is typically not required to be performed by
customers. This design also allows profiles to be loaded into systems without having to recalibrate the DAC output.