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Internal shunt resistor scaling

Use shunt scaling for modules with a shunt resistor.

Before starting the shunt scaling task, define all pertinent parameters for the bridge configuration, and select the desired Shunt resistor where applicable and Shunt polarity (Down Scale or Up Scale) where applicable.

Note that the % Dev parameter is a read only parameter that is automatically updated after the shunt scaling task is completed. The % Dev is the calculated % deviation from the ideal shunt span based on the bridge type, bridge resistance, lead wire resistance and shunt resistance. In brief, it provides feedback to the user on the accuracy of the shunt scaling experiment.

NOTE
Shunt polarity is in terms of the electrical units of mV/V. If the sensor scaling slope is negative, the shunt polarity in physical units is in the opposite direction. For example, the Up Scale option results in a negative swing in the physical units output data.

Select the channel or channels to be scaled and click Shunt Scaling.

ClosedScreenshot

Before scaling, the system sets the scaling parameters to their shunt defaults. Note that the Physical units and Physical span values can be modified before or after the Electrical zero and Electrical span are measured.

ClosedShow defaults

NOTE
To optimize the scaling accuracy, the CX23-R automatically uses the AC Excitation mode and the largest Excitation range available during sensor scaling. If necessary, the excitation mode and range revert to the user-defined values after shunt scaling is completed or canceled and the channel typically requires zeroing.

Perform shunt scaling in three steps. Click Zero to record the unshunted values, which are used to set the zero offset. Click Install to install shunts as defined by the Shunt polarity parameter. Wait for the installed shunt readings to stabilize and then click Measure to record the shunted values. The recorded unshunted and shunted values are used to define the Electrical zero and Electrical span parameters. After scaling is complete, be sure to save the test setup.

NOTE
It is recommended to select the Use system defined sensor scaling filters option in the System preferences to minimize the effects of noise on the accuracy of scaling measurements.