Scaling Overview

Scaling refers to converting the transducer feedback into meaningful units. The RMC uses the Scale and Offset parameters to convert the transducer Counts into measurement units (position, velocity, pressure, force). For example, the Voltage returned by an analog position transducer must be converted to positions in order to be useful for control. In order to correctly convert the transducer feedback to useful units, you must calculate the Scale and Offset parameters.

Position Units

The RMC uses the term Position Units (pu), Pressure Units (Pr), and Force Units (Fr) for the scaled feedback. These are whatever units you have defined with the scale and offset, whether it be inches, millimeters, kilometers, angstroms, psi, Pascals, pounds, Newtons, etc.

Calculating the Scale and Offset

RMCTools provides Scale/Offset wizards to help you calculate the Scale and Offset parameters. You can also calculate the parameters manually.

Scale/Offset Wizards

To access the Scale/Offset wizard, in Axis Tools, in the Axis Parameters pane, click the Setup tab. Expand the Tools and Wizards section. Click Launch to open the Scale/Offset Wizard.

Note:
Before using the Scale/Offset Wizard, you must define the axes and set the transducer type parameters.

Manual Calculation

The methods of calculating the scale and offset parameters depends on the axis type. See the scaling topic for your axis type:

Analog Position Scaling

Analog Velocity Scaling

Analog Acceleration Scaling

Analog Pressure/Force Scaling

MDT Scaling

SSI Scaling

Quadrature Scaling

Resolver Scaling

Rotary Scaling

Scale and Offset Parameters

The following parameters converting the transducer feedback Counts into meaningful units. Each axis, whether a control axis or reference axis, has these parameters:

• Scale
  On a linear axis, the Position, Pressure, Force, or Velocity Scale defines the number of Actual units (position, velocity, pressure or force) per count or volt returned from the transducer.

• Offset
  On a linear axis, the Position, Pressure, Force, or Velocity Offset moves the zero point of the Actual units to where the user wants it.
  On a rotary axis, the Position Offset defines the lower range of the position range.

• Count Offset
  This parameter is used for Absolute Rotary axes to determine where the zero point of the counts should be.

• Position Unwind
  On a rotary axis, the Position Unwind defines the span of the position range.

• Count Unwind
  On a rotary axis, the Count Unwind defines the range of counts over which the Position Unwind spans.

 

See Also

Scale/Offset Wizard

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