ETMR ring encoders

ETMR encoder series is incremental ring sensors which operation is based on the principle of magnetic fields.

Main specifications

Ring encoders are sensors that use a special ring as a scale. In magnetic devices magnetic poles are marked on this tape. The sensor records direction and rotation speed of each mark through a certain point.

Presented encoder belongs to incremental type, so starting point must be entered before work. After completion of work and shutdown, the specified parameters are disappear and therefore they must be re-entered in other cycles.

The device has two channels of output signal: A and B. They allow determining the speed and rotation direction. Channel A determines the number of marks per revolution, and channel B monitors the direction, clockwise or counterclockwise.

The outgoing signal has the form of square waves. In general, series models can have resolutions up to 4096 ppr. ETMR incremental sensors are available with following resolutions:

  • 64ppr;
  • 128 ppr;
  • 256 ppr;
  • 512 ppr;
  • 1024 ppr;
  • 2048 ppr;
  • 4096 ppr;

Resolution 64 pulses per revolution is available only when used with a shaft ø24-28mm. Manufacturer is also can make a model with special resolution on request.
The device is able to rotate with speed up to 8000 revolutions per minute. One of the main advantage of magnetic method is the fact that both parts do not have physical touch during operation.

Electrical specifications

There are several versions of the presented sensors. They have common characteristics and features in the design and are divided by three types of electrical interfaces:

  1. Push-pull.
  2. Line driver.
  3. RS-422.

They are specified in the order code. The letter (P) indicate push pull, (L) - line driver, and (RS) - RS-422.

Power supply will depend on the type of selected interface. Line driver interface encoders work with 5V DC, push-pull and Rs-422 - with 5 ... 28V DC. It is important to pay attention to this when choosing a model. Devices can work with outgoing frequency up to 350 kHz.

Mechanical specifications

The sensor body is made of anodized aluminum and has an IP67 protection level. That is, it is completely protected from dust and can withstand even short-term dive under water.
Magnet actuator is made of stainless steel 1.4305 / AISI 303. It is important to note that there are tight tolerances for its installation (1mm axial and 0.1mm radial).
Such level of resistance allows sensor to be used even in the harshest conditions in production.
There are available several sizes of rings diameters. The outer diameter ranges from 41.2 to 48 mm.
The internal holes of the ETMR encoders can be following:

  •  9 mm;
  •  9,52 mm;
  •  10 mm;
  •  11 mm;
  •  14 mm;
  •  19 mm;
  •  24 mm;
  •  28 mm.

Reliable design also has ability to resist shock and vibration. Encoder can withstand mechanical shocks up to 50G and vibration up to 20G with a frequency of 10 ... 2000Hz.

Magnetic sensors also can work in wide range of temperatures. They can operate at temperatures from -20 to + 85 ° C or -4 to + 185 ° F. Storage conditions are similar.

One of the main advantages of the sensor is its miniature size. The width of the device is only 11 mm. Such dimensions can significantly reduce the space for the installation.
To sum up can say that ELTRA's ETMR series has a number of advantages and it is a miniature, accurate and reliable device. It perfect for conditions when a magnetic ring encoder is needed. You can find it on our website

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