How to select a magnetic encoder for your system?

Thriving automation is the future of businesses. Innovative solutions, controllers or sensors affect the quality, repeatability and safety of production processes and more.

Measuring devices are increasingly taking advantage of natural magnetic phenomena, as exemplified by encoders. Discover how a magnetic encoder works and what to consider when choosing one.

What are magnetic encoders?

A magnetic encoder is a type of sensor that controls motion. Its installation enables you get feedback information in relation to rotation or linear position, which is transmitted to the main control system.

The operation of the component, depending on its type, is to convert the rotary or linear motion of machines into an electrical signal. The resulting signal is then routed to the control system, where it is read. A magnetic encoder makes it possible for us to read:

• the position of machines with high accuracy,

• the angle and number of revolutions of the shaft in the motor,

• rotational speed and the direction of its generation.

It is worth noting that the magnetic encoder does not require the sensor to be in direct contact with the rotating axis. Thanks to this solution, the device is characterised by much greater durability and robustness. The minimum number of moving parts eliminates the risk of accidental malfunctions due to mechanical damage.

Depending on the demand, two types of encoders can be distinguished. Their division is related to the construction and technical parameters. In conditions where it is necessary to provide protection against dust or water ingress of the device, they are placed in a special housing - they have a degree of protection IP67.

In cases where there is no need for environmental protection from external factors, devices are used where the integrated cover is dispensed with.

What is the principle of operation of the magnetic encoder?

The operation of the magnetic encoder is crucial for the automation of various processes in manufacturing. Its presence is the absolute basis for various types of measurements.

In a magnetic device, each measured position is determined by a magnetic field vector. This is made possible by a magnetic disc mounted on the device's shaft. It is responsible for generating the magnetic field.

It is also worth noting that the magnetic encoder is additionally equipped with a Hall effect sensor, which usually comes in the form of an integrated circuit. A plate of semiconducting material is used as the base in this case, which is then placed in a magnetic field.

When a voltage is applied to the plate, it causes electrons to flow in the correct direction, that is perpendicular to the magnetic field lines. By measuring the voltage at individual electrodes, it is possible to determine very accurately the intensity of the magnetic field in which the sensor is placed.

The magnetic field itself on the other hand, produces a Hall voltage, which is then converted into a digital output signal.

The operation of the component also depends on whether one chooses an incremental encoder or an absolute encoder. In the case of incremental encoders, it is necessary to establish a reference base for their measurement system, i.e. the so-called zeroing. In the case of absolute encoders, this is not required. Encoder types are also distinguished by other interfaces. The most common are BiSS and SSI.

What are the key factors in selecting a magnetic encoder?

The choice of a magnetic encoder should not be random. One of the key elements to consider when matching it is resolution. The resolution of an encoder relates to the number of pulses that are generated during one full revolution, which translates into the accuracy of the readings.

It is necessary to match the resolution of the device to meet all the requirements of the application.

Other parameters of a magnetic encoder that are worth paying attention to are the size of the housing, if equipped with one, the diameter of the shaft or bore, as well as the mounting method.

The widespread market use of this type of solution has led to the development of a large range of devices that can easily be tailored to the specifics requirements of a given application.

When selecting a suitable magnetic encoder important factors to take into account are supply voltage, output signal or the communication interface.

In addition, encoders can also be matched with additional accessories to facilitate their operation. These include various types of displays, magnetic tape terminations or cable protection accessories.