High-resolution absolute rotary Eltra encoders


High-resolution absolute encoders are sensors that are capable of measuring with good accuracy and repeatability of results.


  1. High-resolution absolute multiturn encoders
  2. High-resolution absolute eltra encoders with solid shaft
  3. High-resolution absolute eltra encoders with hollow shaft

High-resolution absolute multiturn encoders

Sensors of such type can indicate the absolute position of its own shaft. This means that even when it just turned on, the device can immediately accurately indicate shaft displacement.

Absolute encoders can be single-turn and multi-turn. In the first case, they calculate the parameters only during one revolution, and then main data is reset. Multi-turn devices allow counting over several rotations.

Therefore, multi-turn sensors have two resolutions:Multiturn encoder design

  1. Single turn
  2. Multi turn

Single-turn resolution is displayed in pulses per revolution (ppr), and multi-turn resolution in the number of turns. These indicators also can be measured in bits.

For example, a single-turn resolution of 13 bit will be equal to 8192ppr (2 ^ 13), and a multi-turn resolution of 14 bit will be equal to 16384 turns (2 ^ 14). Sometimes the resolution of the multiturn encoder may be indicated in the total sum of both bytes’ resolutions. Hence, the main resolution in the current example will be 27 bits.

Eltra s.p.a company has released several models of absolute encoders with a high level of accuracy.

High-resolution absolute eltra encoders with solid shaft

Shaft type is one of the most important encoder’s characteristics. High-precision encoders from Eltra with a solid shaft include the following series:

  • EAM 58B
  • EAM58C
  • EAM63A
  • EAM 63D
  • EAM 63E
  • EAM 90
  • EAM 115 A

Models of the same series have almost identical characteristics and differ only in the type of coupling.

EAM58 B / C is a series of encoders for using in standard applications. They have a 13-bit single-turn resolution (8192ppr) and a 14-bit multi-turn (16384 turns) resolution.

EAM58 B has a synchronous flange with a diameter of 50mm. It can be installed axially or radially. Such sensors can work with both SSI and Bit Parallel. The shaft diameter in 58B is equal to 6mm.

EAM58C is fixed using clamping flange Ø36mm and is intended for general industrial use. The diameter of the shaft in this model is 10 mm.

EAM 63A / D are also standard absolute encoder models designed for general industrial use. Both models have a shaft diameter of 9.52 mm. Their total resolution is equal to 27bit (13 bits singleturn and 14 multiturn).Absolute eltra encoders with high resolution photo

EAM 63A is a model that is mounted using a synchronous flange with a diameter of 31.75 mm. There are several types of outputs for connection. The EAM 63 D is identical to the previous model; however, it is fixed by 50mm centering square flange.

EAM 63D is mounted on centering square flange Ø31,75mm and can operate with an electrical SSI or Bit Prallel interfaces. OptoASIC technology for optical encoders is used to work here.

EAM 90-115A is a series of sensors which working with the Profibus protocol. Their main resolution is 25 bit (13 bit singleturn / 8192ppr and 12 bit multiturn / 4096 turns). For quick setup, the device can be supplied with terminal box or M12 connector.

EAM 90A is a model with Ø40mm synchronous flange. It has two available versions for single-turn resolution of 4096 and 8192 ppr. The shaft diameter also has two options and can be 9.52 or 10mm.

EAM 115A is an encoder model with a REO444 flange. The sensor has a stainless steel solid shaft with a diameter of 11mm. Its electrical interface is PROFIBUS DP class 2. For data transfer, the converter uses a binary code.

EAMX 80 is also may be included in this category. It is a special sensor with installed explosion protection. This sensor is a multiturn encoder and has a total resolution of 27 bits.

Its feature is a high level of enclosure protection (IP65), as well as compliance with the requirements of the EC-TYPE Examination Certificate Certificate CESI 04 ATEX 082.

High-resolution absolute eltra encoders with hollow shaft

The second type of high-resolution multi-turn sensors is hollow-shaft encoders. This category includes the following series of encoders by Eltra:

  • EAM 58FEAM 63F eltra encoder scheme
  • EAM 63 F
  • EAM 63 G

EAM 58F is an encoder model for use in standard factory applications with a blind hollow shaft. The sensor uses optical technology OptoAsic + gears for operation. Such encoder has a resolution of 27bit. 

The device is connected using stator coupling. It has push-pull as an electrical interface.

EAM 63F / G is a series for general industrial purpose encoders with a hollow blind shaft. Its bore diameter is in the range of 8 to 15mm.

The device has a resolution of 13bit (8192ppr) singleturn and 14 bit (8192 turns) multiturn. Device accuracy is ±1 / 2 LSB.

EAM 63F has a blind hollow shaft with spring. The device works with both binary and gray code.

EAM 63G is mounted using a blind hollow shaft with a torque pin. Such sensor can work with negative and positive logic.

As a conclusion, it can be said that Eltra s.p.a. created several types of absolute sensors with a different coupling that are suitable for most common industrial cases.

On our website Eltra-encoder.eu you can find all presented models.




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