incremental scale encoder by Eltra

Linear encoder is a device that can determine the movement of an object along single axis.


  1. Incremental linear encoder principle
  2. ER Series
  3. Series Features
  4. Mechanical specifications

Incremental linear encoder principle

By the principle of measurement, such sensors are divided into optical and magnetic. Both types have their own scale and analyze its shift from the start point. The user sets zero point, before starting work.

Optical devices operate using a light beam that passes through its scale. On such strip, there are special marks through which light passes to the transducer.

Magnetic devices tracks movement by calculating of changing magnetic fields. Special poles are placed on the strip and with their movement, the magnetic parameters are changing. The most popular analysis tools in such systems are Hall sensors.

The optical method determines measuring parameters more accurately, but the magnetic method is more reliable and less susceptible to environmental conditions.

ER Series

Eltra ER encoders are produced with optical or magnetic operation principle. The device is mounted on the system using joint heads.

 Eltra s.p.a. produces following series of incremental linear encoders:

  • ERA (0.2mm)
  • ERB (0.1mm)
  • ERC (0.04 mm)
  • ERD (1 mm)
  • ERE (0.5mm)
  • ERF (0.2mm)

The resolution for each type is indicated in brackets. In linear sensors, the accuracy indicator is determined by the distance between each mark on the scale. Closer located marks provide results that are more accurate.

ERA model uses optical principle of operation; other series work with magnetic sensors. Presented devices also differ in the direction of reference. In the ER(A), channel A leads channel B, in other types B leads A.

Total length of the scale in models is from 100 to 500 mm.

Series Features

Company produces assemblies with different location of the zero point.

The following ER linear encoder options are available:

  • Without zero pulse
  • Zero index on the right
  • Zero index on the left
  • Zero index in the center

Such feature allows customer to choose the most suitable unit.

Device has a very fast piston stroke of 1 m / s. This means that it can move along its entire length during 0.5 seconds.

The encoder is connected to the system using a radial cable. Its standard length in basic compilation is 1.5 m. The following lengths are also available:

  • 2m
  • 3m
  • 5m
  • 10m

In addition to the main sizes, the manufacturer can supply cables of the required length at special order.

Company releases equipment with electrical interfaces: NPN open collector, push-pull and line driver. The maximum output frequency parameter can reach up to 100 kHz.

Load current in the NPN open interface can reach up to 50mA per channel and in push-pull or liner driver it is equal up to 29mA per channel. The power supply of the system is carried out using 5 V DC or in the range from 8 to 24 V DC.

Mechanical specifications

ER Series devices are created with a sturdy housing made of painted aluminum. Piston is made of stainless steel. Due to such materials, company increased the protection rating of the device to IP 64. The total weight of the encoder is in the range from 400 to 1000 g.

Sensor is mounted using 2 joint heads and hole Ø6 mm. The instructions indicate where to connect each color wire. Device may operate at temperatures from -10 to 60 ° C (+ 14 ... 140 F) and can be stored at -25 ... + 70 ° C (-13 ... + 158 F).

All models in the series are fully certified and tested in accordance with the requirements of directives 2011/65 / EU and 2914/30 / EU.

In general, Eltra has released a six universal series of linear incremental encoders. Due to their variability, they may perform a wide range of linear measurements.

On website you can find all the presented series of ER.

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