## Additional Information

## Types of Custom Scale:

**Slope** and the **Y-intercept** define the new values, where the **Slope** converts from Volts to the scaled units and the **Y-intercept** adjusts for any offset in the scaled units. As mentioned, the NI 9237 reads input in mV (notice the default **Pre-Scaled **units below are Volts). There is not a mV setting; Therefore, remember to convert the reading from mV to Volts.

Slope can be determined by the maximum value of the transducer divided by the transducer's rated output (R.O).

Ex: 100 lb tension/compression load cell with 2 mV/V R.O., an offset of 5 lbs, where compression displays a negative value.

**Note: **The linear scale is the only scaling option that enables the use of a negative slope.

*slope = 100 lbs /.002 V/V = 50000 lbs/(V/V)*

The equation for this situation would be *y = -50000 * X + 5*

Since the maximum/minimum values for X, the measured value, are +/- .002 V/V, the new **Signal Input Range** is:

*maximum = 50000 lbs/(V/V )* .002 V/V + 5 lbs = 105 lbs*

minimum = 50000 lbs/(V/V) * -.002 V/V + 5 lbs = -95 lbs

Remember that there will not be a symmetric **Signal Input Range **anymore, shown below in red, when using an intercept.

**Note**: Verify the custom scale is applied and the new **Scaled Units** are displayed correctly, shown above in blue.

This scale is convenient for directly assigning **Pre-Scaled Values** to their corresponding **Scaled Values**, where the maximum and minimum **Pre-Scaled Values **are +/- the transducer's Rated Output (R.O.) in Volts.

Ex: A 100 lb tension/compression load cell with a 2 mV/V R.O.

**Note: **Remember to verify a custom scale is selected and the new units appear as expected in the DAQmx task as shown in blue in the task configuration.

A Table Scale can be used similar to a Map Ranges Scale by directly assigning the **Scaled Values**. However it can also be used to input the calibration values from the Certificate of Calibration provided with the transducer.

Ex: The Certificate of Calibration for a load cell lists the load as -100 lbs and the mV/V as -1.95, as well as, 100 lbs and 1.98 mV/V.

Select **Add** and enter - 0.00195 for **Pre-Scaled** and -100 for **Scaled**. Repeat for the next set of values with .00198 for **Pre-Scaled** and 100 for** Scaled**.

**Note:** Remember to verify a custom scale is selected and the new units appear as expected in the DAQmx task as shown in blue in the task configuration.