Basic function principles

The box acquires the 90° phase-shifted digital output signal of an incremental encoder on channels A and B. The zero pulse is acquired on channel C. These signals are converted into a position value with quadruple evaluation with the aid of the quadrature encoder and the 32-bit counter. The latch and reset functions enable the exact referencing and saving of the counter value, irrespective of the speed.

Incremental encoders divide a 360° rotation of the encoder axis into individual steps (increments) and mark a full revolution by means of a special mark (zero pulse).
The phase angle between the signals on channels A and B sets the counting direction.
Up: signal on channel A leads signal on channel B by 90°
Down: signal on channel A lags signal on channel B by 90°

In case of single evaluation, the positive edges on channel A are counted.
In case of quadruple evaluation, the positive and negative edges on channel A and channel B are counted.

Whereas absolute value encoders deliver an absolute and unambiguous position value over the complete travel path directly after switching on, it is necessary with incremental encoders to perform a reference run (homing) after switching on in order to be able to determine an unambiguous position.
Referencing can be carried out, for example, with the aid of reference cams or using the zero pulse of the encoder.