Absolute rotary encoders

Absolute encoders output the angular position of a shaft as a unique value and retain the position even after a power interruption. SCN supplies absolute encoders from Posital, including IXARC rotary encoders in the UCD, OCD, OCE, OCM and TCR model families. They are used for position and angle measurement in industrial automation, machine building, mobile machinery and vehicles. Our engineers help you choose the right interface, resolution, shaft or hollow-shaft design and connector for your application.

Solution areas

Product categories

Filter by attributes

Acceleration

Accuracy (°)

Accuracy (%)

Approvals

Auxiliary contact

Built-in I/O

Capacity

Circuits

Coil Voltage

Communication Interface

Switching output

Contact config

Mechanical cycles

Continuous current

Control voltage DC

Control voltage AC

CPU performance

Data logging

DIN-rail

Electrical connection

Number of poles

Coding

Connector design

Cable jacket

Expansion slots

Fieldbus/Interface

Flange size

Function

Housing

I/O slave module

IP Classification

Load Cell Type

Material

Material in contact with medium

Max current DC

Max current AC

Max operating speed

Max system voltage DC

Max system voltage AC

Measuring range (mm)

Measuring range (bar)

Measuring range (kg)

Measuring range (°C)

Measuring range (°)

Torque

Power (kW)

Digital inputs

Digital outputs

Analog inputs

Analog outputs

Measuring range (l/min)

Measuring range (kHz)

Measuring technology

Measured variable

Memory

Modules

Mounting

Nominal diameter

Number of ports

Operating system

Outer Diameter

Output Voltage

Output current

Efficiency

Phase

Photocell type

Positions

Pressure type

Pressure limit PSI

Process connection

Probe length

RAID

Rated power

Remote Access

Resolution Multiturn

Resolution Singleturn

Screen size

Shaft Diameter

Storage

Stroke length

Supply voltage DC

Supply voltage AC

Temperature range

Form Factor

Touch

Type of Switch

Voltage

dB(A)

Brands

Absolute encoders – rotary position for machines, mobile hydraulics and automation

An absolute encoder, also called an absolute rotary encoder, gives every shaft position its own unique value. The position is known as soon as the power is switched on, without a reference run, which is why absolute encoders measure angle and position in cranes, wind turbines, packaging and printing machines, mobile machinery and robotics. SCN supplies absolute encoders from Posital: magnetic IXARC encoders in the UCD family, optical encoders in the OCD, OCE and OCM families, and redundant CANopen encoders in the TCR family.

The range covers single-turn and multi-turn models with solid or hollow shaft, resolutions up to 16 bits per turn, IP69K versions for washdown and outdoor use, ATEX versions, and interfaces from SSI and analog 4–20 mA or 0.5–4.5 V to IO-Link, CANopen, PROFIBUS-DP, PROFINET and EtherCAT. If you only need speed or relative movement, incremental encoders are a simpler choice. For straight-line movement, see incremental linear position sensors. All sensor types are listed under Sensors.

How to choose: first decide between single-turn and multi-turn, and the resolution you need. Then choose the interface your controller uses, solid or hollow shaft and its diameter, flange, and connector or cable outlet. Finally check the IP rating, temperature range and any approvals the environment requires.

Frequently asked questions

What is the difference between an absolute and an incremental encoder?

An absolute encoder reports the actual position as a unique value, while an incremental encoder only sends pulses that the controller has to count from a reference point. After a power failure the absolute encoder knows its position at once; an incremental encoder needs a new homing run. Incremental encoders are simpler and well suited to measuring speed.

Single-turn or multi-turn – which do I need?

A single-turn encoder measures the angle within one revolution and starts again after 360°. A multi-turn encoder also counts the revolutions, which is needed when the shaft turns many times over the travel, for example on a winch, a spindle or a telescopic boom. Posital's IXARC multi-turn encoders count turns with a Wiegand energy-harvesting sensor, so they need neither battery nor gearbox.

Magnetic or optical absolute encoder?

A magnetic encoder is the robust choice: it tolerates shock, vibration, dust and moisture and is available up to IP69K. An optical encoder reads a coded disc and gives the highest resolution and accuracy, which suits precise positioning in machine tools and printing. For most machines, cranes and mobile equipment a magnetic encoder typically offers enough resolution at a lower cost.

SSI, CANopen, IO-Link or Ethernet – which interface should I choose?

Choose the interface your controller already uses. SSI is a simple and fast point-to-point interface common in motion control. CANopen is widespread in mobile machinery, IO-Link gives easy parameter setting over standard cables, and PROFINET, EtherCAT or PROFIBUS-DP connect the encoder directly to the PLC network. Analog 4–20 mA suits simple angle monitoring.

Not sure which model you need?

Get help choosing
Read more in our guides

Facts and advice that make the choice easier.

Absolute vs incremental encoder – how to chooseIP ratings explained – IP65, IP67, IP68 and IP69KAll guides