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Magnetic multi-turn

An alternative to optical encoders

ASM Sensors (Germany) has introduced its latest Posihall magnetic multi-turn encoders. These absolute sensors come with CANopen and J1939.

The sensors support CANopen and J1939 (Photo: ASM)

The Posihall magnetic encoders measure absolute angular position of a shaft over multiple revolutions by utilizing a gear coupled multi-hall sensor system that uses a magnetic nonius (vernier) principle. In contrast to current magnetic encoder technologies, it is a true-absolute technology ensuring reliable and correct positioning even after disturbances such as a power failure, said the company. There are three versions of Posihall sensors available.

The measurement range for the PH36 is up to 31° revolutions x 360° revolutions and for the PH58/PH68 up to 255° revolutions x 360° revolutions. The sensors are available with digital (CANopen, J1939, and SSI) and analog outputs. The CANopen outputs support the CiA 301 application layer (version 4.0.2) as well as the CiA 406 encoder profile (version 3.2). The single-turn linearity is 0,3 %. The sensors reach a resolution of 14 bit.

The products can be mounted directly onto the machine’s rotation axis. The sensor electronics are completely enclosed and protected by a rugged housing. The devices are available in protection class up to IP69. The non-contact magnetic multi-hall technology is able to detect measuring data even if the machine housing is filled with water or oil. The sensor body has an integral shielding against magnetic fields. It works in environments with magnetic field strengths up to 0,5 T. For safety applications the sensors are also available with redundant outputs. The angle measuring sensors operate with levels of shock and vibration and in a temperature range of -40 °C to +85 °C.

The sensors are suited for applications such as packaging machines, food processing machines, mobile working machines, offshore applications, or wind and solar energy plants.


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