Custom Scaling

You can use a custom linear scale to scale values using the equation y = mx + b, where x is a pre-scaled value and y is a scaled value.

When you select a range for a channel, the FieldPoint software automatically scales I/O data to the engineering units you select. Custom scaling enables you to apply a second level of scaling that conforms to a simple, linear slope-intercept equation. Although range selection is a form of scaling, in this discussion of custom scaling we refer to the input and output values as they appear in software as pre-scaled values.

For example, suppose you want to relate pre-scaled values to scaled values according to the following linear scale:

y = 2x + 0

where x is a pre-scaled value, and y is a scaled value.

For input operations, if the device acquires a pre-scaled value of 2, the scaled value that is read is 4. For output operations, if you write a scaled value of 2, the device generates a value of 1.

• Enable Scaling—Check this box to apply the custom linear scale to data on the selected channel.
• Slope—The slope m in the equation y = mx + b.
• Y-Intercept—The y-intercept b in the equation y = mx + b.
• Equation—Displays the linear equation for the scale.
• Pre-Scaled Range—The range in engineering units that the FieldPoint software is configured to apply to channel data automatically, without custom scaling.
• Scaled Units—The engineering units that the FieldPoint software displays for the channel in MAX.