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Magnetic encoders In magnetic encoders, a small permanent magnet is installed on the spinning mo- tor shaft. Sensors in the stator capture the changes in the magnetic flux. The signals are evaluated in the encoder and transmitted to the controller as pulses or as an absolute sig- nal. Magnetic encoders are typically very small and resilient to dirt. EASY, TSX and MAG encoders − Integrated circuit based on Hall sensors and interpolator − EASY incremental: Factory programmable resolution from 1 to 1024 counts per turn, with index channel and line driver − TSX incremental encoder for peripheral mounting: Programmed for specific rotor and stator; 2 channels plus commutation signals − EASY absolute: Single-turn with 4096 states (12-bit) and Biss-C or SSI interface − MAG incremental: Various resolutions available (up to 256 counts per turn); recom- mended for battery operation MR encoder (incremental) − Magneto-resistive Sensor with/without inter- polator − Various resolutions available (up to 1024 counts per turn) − With/Without index channel and/or line driver − Magnetoresistive sensor − Up to 1024 counts − With/without index channel and/or line driver GAMA and QUAD encoder (incremental) − Digital Hall sensors without interpolation − Line driver not available − GAMA: 12 or 16 counts per turn − QUAD: 1 count per turn (4 states) − Please note: For operation with maxon controllers, at least 16 counts per turn are required.
DC tacho In principle, any maxon DC motor can be used as a DC tacho. For motor-tacho combinations, we offer a DC tacho that has the tacho rotor mounted directly on the motor shaft. Characteristics − Output DC voltage proportional to the speed due to precious metal brushes − AlNiCo magnet for high signal stability even with temperature fluctuations − Without additional tacho bearing; no added friction torque − No couplings, high mechanical resonant frequency Resolver The resolver is attached to the continuous shaft of the motor and aligned perfectly with the rotor's magnetic field. A high-frequency alternating voltage (10 kHz) is transmitted to the rotor via a transformer. During retransformation on two stator coils, the signal is modulated with the sine/cosine of the rotation angle. This makes it possible to derive the position of the rotor. Characteristics − Robust, for industrial use − Long service life − No mechanical wear − Interference-free signal transmission over long distances − No sensitive electronics − Special signal evaluation required − Only one encoder for position and speed information − EC motors with resolvers are delivered without Hall sensors
EMT (absolute) − Multi-turn absolute encoder − Resolution: 16-bit multi-turn, up to 17-bit single-turn − BiSS-C or SSI interface − Equipped with Wiegand wire technology, thus no batteries required. Optical encoders In optical encoders, an LED emits light through a finely structured code wheel (HEDL, HEDS) or directed at a structured reflector (RIO) attached to the motor shaft. The receiver converts the light/dark signals into electrical currents, which are amplified and turned into electrical pulses by the respective electronics. Optical encoders typically have a high resolu- tion and high accuracy. RIO encoder − Reflective interpolated optical encoder − Very high resolution (typically 4096 to 16 384 counts per turn), programmable at the factory − With index channel and RS422 line driver − Very small size
Encoder attachment HEDL, HEDS − Transmissive optical encoders − With line driver RS422 (HEDL) − Relatively large size Inductive encoder
With inductive MILE encoders, a high-frequen- cy alternating field is transmitted via transform- er while being modulated angle-dependently using a structured copper disk. Characteristics − Highly resistant to magnetic and electrical fields as well as soiling. − High speeds possible − High accuracy − Line driver (can be acc. to RS422)
Technology – short and to the point 75
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