Absolute Standard Rotary Encoders Now Also Available with Inductive Scanning

The ROC/ROQ 400 series standard rotary encoder program with 58 mm diameter has now been broadened by versions with inductive scanning—the RIC / RIQ 400 series. Depending on the respective applications and accuracy requirements, both inductive and optical absolute encoders are possible options. The mechanical dimensions of the encoders with inductive scanning are identical to those of the optical encoders.

In the version without incremental signals (EnDat21), the new inductive encoders with EnDat 2.1 interface feature an accuracy of ± 480'', a single-turn resolution of 13 bits or 18 bits, and a multiturn-resolution of 12 bits. Now, with the EnDat01 version, encoders are available that provide incremental signals in addition to the absolute position values. The position values are transmitted with clock frequencies up to 2 MHz. The minimum data transmission time is approx. 25 µs and is therefore sufficient for standard rotational speed control designs.

The inductive position encoders are installed in servo drives in applications in which the position resolution of resolvers is inadequate. Moreover, conventional resolvers cannot provide absolute positions over multiple revolutions, which is why optical or inductive multiturn encoders are increasingly preferred.

Servo drives with inductive rotary encoders enjoy advantages over resolvers in terms of positioning accuracy, speed stability and control dynamics. This is made possible by the greater control bandwidth and a significantly higher number of signal periods for the formation of the singleturn position value. The position value is produced by electronics already integrated in the encoder, and is transferred as purely digital information to the higher-level electronics over the fast bidirectional EnDat interface. As an option, the information can be transferred redundantly as an analog signal. An integrated readable and writable EEPROM makes user parameters available to the subsequent electronics at all times, enabling the encoder and its environment to self-configure over the synchronous serial interface.

The encoder’s real multiturn capability frees the system from the need to be “homed” after power interruptions or switch-on. Conventional battery-supported systems requiring regular maintenance are no longer needed. Alarm and diagnostic functions ensure high system availability rates.

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