Motion Feedback Resource

Encoder &
Linear-Scale Calculator.

Calculate encoder PPR, quadrature counts, travel resolution, expected pulse counts, actual movement and axis correction from measured travel.

‹ Back to Resources

Rotary Encoder Resolution

Convert PPR Into Machine Travel.

Enter the encoder's published PPR or CPR, the controller's edge-count multiplier and the machine travel produced by one encoder revolution.

Encoder Resolution

Calculate final counts per revolution, pulses per inch or millimeter and travel per count.

Encoder PPR / CPRUse the manufacturer's single-channel pulse or quadrature-cycle rating.Quadrature MultiplierHow the controller or interface counts A/B edges.Travel per Encoder RevolutionTravel UnitMaximum Encoder Speed (RPM)Interface Count-Rate LimitCounts per second. Verify against the input-device specification.

Final Counts per Revolution—

Counts per Inch—

Counts per Millimeter—

Travel per Count—

Count Frequency—

Input Capacity Check—

Final counts/rev = PPR × multiplier
Travel/count = travel per revolution ÷ final counts/rev

Move & Count Calculator

Predict the count change for a commanded move or convert an observed count change into actual travel.

Counts per UnitMay be entered directly or populated from the encoder calculator.UnitTarget MoveObserved Count Change

Expected Count Change—

Travel From Observed Counts—

Required Encoder PPR

Calculate the encoder PPR required to reach a desired number of counts per unit.

Desired Counts per UnitTravel per RevolutionQuadrature Multiplier

Calculated PPR—

Nearest Whole PPR—

PPR and Quadrature TerminologyQuadrature describes the 90-degree relationship between channels A and B. The ×2 or ×4 multiplication occurs in the controller or encoder interface when it counts additional signal edges. Confirm whether the encoder datasheet specifies lines, pulses, cycles, PPR, CPR or final counts before entering the value.

Linear Scale Resolution

Convert Published Scale Resolution Into Counts.

Use this section for incremental linear scales, draw-wire encoders and other feedback devices whose specification is expressed as distance per pulse or count.

Linear-Scale Resolution

Account for whether the published resolution is a raw quadrature cycle or already represents the final controller count.

Published ResolutionResolution UnitPublished Resolution MeansQuadrature MultiplierTarget MoveTarget-Move UnitObserved Count Change

Final Travel per Count—

Counts per Millimeter—

Counts per Inch—

Expected Counts for Move—

Travel From Observed Counts—

If resolution is per raw cycle: final travel/count = published resolution ÷ multiplier
If resolution is already per final count: no additional multiplier is applied

Scale Resolution CheckSome scale manufacturers publish resolution after internal interpolation, while others describe the raw signal period. Do not automatically multiply a published 5 µm resolution by four. Verify the exact definition in the scale and controller documentation.

Axis Calibration Check

Compare Displayed Travel With Measured Travel.

Record the control position and independent measurement at the beginning and end of a move. The calculator uses the change in each reading, so the starting values do not need to be zero.

Displayed vs. Measured Travel

Calculate position error, correction percentage and a corrected pulses-per-unit or travel-per-count setting.

Displayed Start PositionDisplayed End PositionMeasured Start PositionMeasured End PositionPosition UnitExisting Parameter TypeExisting Parameter Value (Optional)

Displayed Travel—

Measured Travel—

Position Error—

Travel Error—

Parameter Correction—

Corrected Parameter Value—

For Counts or Pulses per Unit

Correction factor: Displayed ÷ Measured
New parameter: Old × correction factor

For Travel per Count

Correction factor: Measured ÷ Displayed
New parameter: Old × correction factor

Position error = measured travel − displayed travel
Travel error % = position error ÷ displayed travel × 100

Calibration ProcedureUse a calibrated independent measuring device, remove backlash by approaching both readings from the same direction, and use the longest practical move. Repeat the test in both directions and at several positions before changing a machine parameter. Confirm the control manufacturer's definition of the parameter before entering the corrected value.

Encoder &Linear-Scale Calculator.