The incremental encoders are constructed according to optical or magnetic principles as well as in a single-chip version. Available at the encoder outlets are two 90°e phase-shifted square wave signals with up to 10,000 pulses as well as one index pulse per motor revolution in the 3-channel version.
Incremental encoders transmit a specific number of uniformly distributed lines per revolution. All FAULHABER Incremental encoders have at least two channels: A and B. Both channels supply a square wave signal, shifted by 90°e with respect to one another, i.e., one quarter cycle C. Through this shift of the pulses, the motor’s direction of rotation can be determined.
Functionality of incremental encoders
An incremental encoder does not measure absolute positions, but rather relative positions. So incremental encoders determine a position relative to another reference position. For this purpose, the signal edges must be counted forward or backward by the motor control using a quadrature counter according to their edge sequence.
This position value of an incremental encoder, however, will be lost if the power supply is interrupted. A positioning system must therefore move to a defined reference position during commissioning or after a power interruption to initialise the position counter. This process of an incremental encoder is referred to as homing. For the determination of the reference position in incremental encoders, an additional, external sensor, such as a reference switch or limit switch, is usually used.