Understanding Encoder output signals: A quick guide

When selecting an encoder for your application, one of the most important factors to consider is the output signal. It determines how position or speed data is communicated from the encoder to your control system - and choosing the right type can make a significant difference in performance and reliability.

What are encoder output signals?

Encoder output signals are the electrical signals generated by an encoder to represent motion. These signals are read by devices such as PLCs, drives, or controllers to track position, direction, or speed.

There are two main categories: incremental and absolute.

Incremental signals

Incremental encoders output pulses as the shaft rotates. The most common format is A, B, and Z channels:

• A & B channels: Provide quadrature signals used to determine direction and count movement.

• Z channel: A reference pulse that occurs once per revolution

These signals are widely used because they're simple, cost-effective, and suitable for many general automation tasks.

Absolute signals

Absolute encoders provide a unique position value at all times - even after power loss. Instead of pulses, they transmit digital data representing the exact shaft position.

Common output protocols include:

• SSI (Synchronous Serial Interface)

• BiSS

• Fieldbus or Industrial Ethernet systems

  
  

These are ideal for applications where position accuracy and system recovery are critical.

Signal types: Voltage and communication

Encoder signals can also differ in how they are electrically transmitted:

• TTL (Transistor-Transistor Logic): Fast and precise, but more sensitive to electrical noise

• HTL (High-Threshold Logic): Higher voltage, better suited for industrial environments

• Differential signals (e.g. RS-422): Improve noise immunity over longer cable runs

  
  

Choosing the right signal type helps ensure stable and accurate data transmission - especially in demanding environments.

Choosing the right output

The best encoder depends on your system requirements:

• Need simple speed feedback? Incremental may be enough

• Require exact positioning on startup? Absolute is the better choice

• Working in a high-noise environment? Consider HTL or different outputs

At Encoders UK, our expert team can help you select, supply, or repair encoders with the right output for your application - quickly and reliably.

Need Encoder support? Get in touch today!

info@encoders-uk.com

0121 378 5577