An incremental rotary encoder is a feedback device that converts rotational movement into electrical output signals. Depending on its configuration, an incremental encoder can provide information about rotational position, speed, direction, and pulse count to a control system.

Incremental rotary encoders are widely considered for industrial machinery because their output signals can be processed by controllers, PLCs, drives, and other automation equipment. Selecting the correct encoder requires more than choosing a pulse-per-revolution value. Electrical output, maximum speed, shaft dimensions, mounting, environmental conditions, and controller compatibility should also be evaluated.

For industrial applications, you can explore the Sensyor rotary encoder product range to review available rotary encoder solutions.

What Is an Incremental Rotary Encoder?

An incremental rotary encoder measures rotational movement by producing electrical pulses as its shaft rotates.

Unlike an absolute encoder, an incremental encoder generally provides relative movement information rather than a unique absolute position value for every shaft position.

The control system can use the encoder’s output to determine:

• Rotation speed
• Rotation direction
• Relative position
• Distance or movement
• Pulse count
• Motion timing

An incremental rotary encoder is normally mounted to a rotating shaft, motor, machine mechanism, or other moving component.

As the shaft rotates, the encoder generates output signals. The receiving controller interprets these signals according to the encoder’s output configuration.

This makes the incremental rotary encoder an important feedback component in many motion-control systems.

How Does an Incremental Rotary Encoder Work?

The operating principle of an incremental rotary encoder is based on generating electrical signals corresponding to shaft rotation.

As the encoder rotates, its sensing mechanism produces pulses. The number and frequency of these pulses provide information about movement.

For example:

• More pulses over a given period indicate more movement.
• Higher pulse frequency indicates higher rotational speed.
• The relationship between signal phases can indicate direction.
• An index signal, when available, can provide a reference point.

The receiving controller processes the encoder signals and uses them as feedback for the machine.

The exact sensing technology can vary between encoder designs.

A and B Phase Signals

Many incremental rotary encoders use two output channels commonly called A and B.

These signals are phase-shifted from each other.

The control system can analyze the phase relationship between A and B to determine the direction of rotation.

This configuration is often called quadrature output.

For example, when the shaft rotates in one direction, A may lead B. When it rotates in the opposite direction, B may lead A.

The controller can therefore use the signal sequence to distinguish clockwise and counterclockwise movement.

Z Index Signal

Some incremental rotary encoders also provide a Z or index signal.

The Z signal can provide a reference pulse once per revolution, depending on the encoder design.

An index signal can be useful for applications that need a repeatable reference position.

Whether an application requires A, B, Z, or another output configuration depends on the control architecture.

Incremental Rotary Encoder Resolution

Resolution is one of the most important specifications when selecting an incremental rotary encoder.

For many incremental encoders, resolution is specified in pulses per revolution (P/R).

For example, an encoder rated at 1,000 P/R generates 1,000 output pulses per revolution on the specified channel, depending on the manufacturer’s definition.

Higher P/R does not automatically mean that an encoder is better for every machine.

The appropriate resolution depends on:

• Required feedback accuracy
• Machine speed
• Controller input capability
• Required positioning performance
• Signal-processing requirements
• Mechanical transmission

Encoder Frequency Calculation

For an incremental encoder, a basic output-frequency calculation can be expressed as:

Output frequency = P/R × RPM ÷ 60

For example, at 1,000 P/R and 600 RPM:

1,000 × 600 ÷ 60 = 10,000 pulses/second

If the encoder has a much higher P/R value, the resulting signal frequency will also increase at the same RPM.

Therefore, engineers should evaluate the encoder’s resolution and the receiving controller’s input-frequency capability together.

Incremental vs Absolute Rotary Encoder

The difference between an incremental rotary encoder and an absolute encoder is important during product selection.

An incremental encoder can be a practical option when the control system is designed to count pulses and determine movement from the encoder’s signals.

An absolute encoder may be considered when the machine requires absolute position information.

The correct choice depends on the complete system rather than the encoder type alone.

Applications of Incremental Rotary Encoders

An incremental rotary encoder can be used in a wide range of industrial applications.

Industrial Automation

Automation equipment may use incremental encoder feedback for motors, conveyors, rollers, and other rotating components.

The encoder provides movement-related signals to a PLC, controller, or drive.

You can view the Sensyor rotary encoder products for industrial encoder applications.

Servo Motor Systems

Incremental encoders may be used in certain servo and motion-control architectures.

The required encoder resolution, signal type, speed, and electrical interface must be compatible with the servo drive.

CNC Machine Tools

CNC equipment may use rotary encoders for spindle or other rotational feedback applications, depending on machine architecture.

The encoder’s mechanical mounting and signal specifications should be matched to the CNC control system.

Packaging Machinery

Packaging machines often contain rotating rollers, feeders, cutting mechanisms, and other moving components.

An incremental rotary encoder can provide feedback associated with rotational movement.

Printing Machinery

Printing systems can require synchronized movement between rotating components.

Encoder feedback can be used as part of the machine’s control architecture.

Textile Machinery

Textile equipment may include multiple rotating shafts and rollers.

An incremental rotary encoder can provide rotational feedback to the machine control system when its specifications are appropriate.

Robotics

Robotic equipment can use encoder feedback for motors and joints.

The encoder must be selected according to the motor, controller, mechanical space, speed, and feedback requirements.

9 Factors to Consider When Choosing an Incremental Encoder

1. Resolution

Determine the required P/R based on the machine’s movement and feedback requirements.

Do not select the highest available resolution without checking the controller’s signal-processing capability.

2. Output Signal

Check the required output configuration.

Depending on the encoder and control system, options may include different electrical output arrangements.

The PLC, drive, or controller input must be compatible with the encoder output.

3. Maximum Speed

The maximum operating speed of the encoder should be suitable for the application.

Calculate the expected signal frequency at the machine’s maximum RPM.

This is especially important when using a high-resolution incremental rotary encoder.

4. Supply Voltage

Confirm the encoder’s required supply voltage and make sure it matches the available power supply or interface requirements.

5. Shaft Dimensions

Check:

• Shaft diameter
• Shaft length
• Shaft type
• Coupling requirements
• Shaft loading

Even if the electrical specifications are correct, an encoder may not fit mechanically.

6. Mounting Configuration

Review the encoder’s mounting dimensions carefully.

Check:

• Flange type
• Mounting holes
• Bolt pattern
• Installation space
• Orientation
• Clearance

Mechanical drawings should be used whenever possible.

7. Environmental Conditions

Consider the machine’s operating environment.

Important conditions may include:

• Dust
• Water
• Oil
• Temperature
• Vibration
• Shock
• Humidity

The encoder’s protection and environmental specifications should be checked against actual operating conditions.

8. Connector and Cable

Cable length and connector configuration can affect installation.

For OEM equipment, the connector location and cable exit may also need to fit the machine’s mechanical design.

9. Controller Compatibility

The final step is to confirm compatibility with the receiving device.

Check the encoder against:

• PLC
• Servo drive
• Motion controller
• CNC controller
• Counter module
• Industrial control system

The controller must be capable of correctly interpreting the encoder’s output.

How to Install an Incremental Rotary Encoder

Correct installation is important for reliable encoder feedback.

Before installation, review the manufacturer’s mechanical drawing and installation instructions.

Step 1: Check Mechanical Compatibility

Confirm shaft diameter, mounting dimensions, coupling, and available clearance.

Step 2: Align the Encoder

Avoid excessive misalignment between the encoder shaft and the rotating machine shaft.

Step 3: Secure the Encoder

Use the appropriate mounting hardware without applying excessive mechanical force.

Step 4: Connect the Wiring

Follow the encoder’s wiring diagram and pin assignment.

Do not assume wire colors or pin assignments are identical between manufacturers.

Step 5: Check the Output

Rotate the shaft and verify that the expected signals are being received by the controller.

Step 6: Test at Operating Speed

After basic verification, test the encoder under the intended operating conditions.

Common Incremental Encoder Problems

Even when an incremental rotary encoder is correctly selected, installation or system integration problems can affect performance.

No Output Signal

Possible areas to investigate include:

• Power supply
• Wiring
• Connector
• Pin assignment
• Controller input
• Encoder installation

Incorrect Direction

If the detected direction is opposite to the expected direction, check the A/B channel relationship and control-system configuration.

Unstable Signals

Possible causes can include:

• Wiring problems
• Electrical interference
• Incorrect grounding
• Connector problems
• Mechanical vibration
• Signal compatibility issues

The exact cause should be diagnosed using the encoder documentation and the machine’s electrical design.

Incorrect Pulse Count

Check the encoder’s specified resolution and how the controller processes the signal.

Also verify whether the controller is using rising edges, falling edges, or multiple-edge counting.

How to Select an Incremental Rotary Encoder Supplier

Choosing an incremental rotary encoder supplier requires more than comparing prices.

Consider whether the supplier can provide:

• Complete technical specifications
• Mechanical drawings
• Wiring diagrams
• Samples
• Product customization
• Quality-control information
• Production capacity
• Technical support
• Consistent supply
• Appropriate packaging and documentation

For OEM applications, customization may be especially important.

A supplier should be able to understand your mechanical and electrical requirements before recommending an encoder.

Why Consider Sensyor Rotary Encoder Products?

When selecting an incremental rotary encoder, the most important consideration is whether the product matches the machine’s technical requirements.

Sensyor provides rotary encoder products for industrial applications.

Visit the Sensyor rotary encoder page to explore the available product range.

For an OEM or industrial purchasing inquiry, provide information such as:

• Application
• Encoder type
• Required P/R
• Maximum RPM
• Output type
• Supply voltage
• Shaft dimensions
• Mounting dimensions
• Connector requirements
• Environmental conditions
• Required quantity

Providing these details can make technical evaluation more efficient.

FAQs About Incremental Rotary Encoders

What is an incremental rotary encoder?

An incremental rotary encoder is a feedback device that converts rotational movement into electrical pulses or signals. A control system can use these signals to determine relative position, speed, direction, or movement.

How does an incremental rotary encoder work?

As its shaft rotates, an incremental encoder generates electrical output signals. The number and frequency of the signals provide movement information, while multiple signal channels can be used to determine rotational direction.

What does P/R mean on an incremental encoder?

P/R generally means pulses per revolution. It describes the number of pulses generated for each revolution according to the manufacturer’s specified measurement method.

What is the difference between an incremental and absolute encoder?

An incremental encoder generally provides relative movement information through output pulses, while an absolute encoder provides position information associated with the shaft’s absolute position. The appropriate type depends on the control system and application.

Can an incremental rotary encoder measure speed?

Yes. A control system can determine rotational speed by measuring the frequency of encoder pulses over time.

Can an incremental rotary encoder detect direction?

Many incremental encoders use two phase-shifted channels, commonly A and B, allowing the controller to determine rotational direction from their phase relationship.

What is the Z signal on an incremental encoder?

The Z or index signal can provide a reference pulse associated with a particular shaft position, commonly once per revolution depending on the encoder design.

How do I choose the resolution of an incremental rotary encoder?

Choose the resolution based on the machine’s feedback requirements, rotational speed, required movement resolution, and controller input capability. Higher P/R is not automatically better for every application.

Can incremental rotary encoders be used with PLCs?

Yes, when the encoder’s electrical output is compatible with the PLC input and the PLC can process the encoder’s signal frequency.

Can incremental rotary encoders be used for servo motors?

They can be used in servo-related applications when the encoder’s feedback specifications and electrical interface are compatible with the servo motor and drive system.

Where can I find industrial rotary encoder products?

You can visit the Sensyor rotary encoder product page to explore available rotary encoder products.

Conclusion

An incremental rotary encoder converts rotational movement into electrical feedback signals that can be processed by industrial control systems.

When properly selected, an incremental encoder can provide useful information about speed, direction, relative position, and movement. However, choosing the right model requires a complete evaluation of resolution, output signal, supply voltage, maximum speed, mechanical dimensions, environmental conditions, and controller compatibility.

For OEMs and machine builders, supplier capabilities should also be considered. Technical documentation, sample support, customization, production capacity, and technical communication can all affect the encoder selection process.

Before purchasing an incremental rotary encoder, define the machine’s requirements and compare the encoder’s specifications with the actual control system.

For industrial rotary encoder solutions, visit the Sensyor rotary encoder product range.