What does a “two-phase” encoder do?
• A “two-phase” encoder provides a second signal to the system it is feeding that allows the direction of rotation to be determined. This is done by offsetting one signal from the other by 90. One signal is usually referred to as Phase A the other is Phase B. In one direction, Phase A will lead by 90 and in the other Phase B will lead. This is often called quadrature or A Quad B. This scheme is typically used with: regenerative drives, reversing drives, position controls, and length measurements. • What does “direction sensing” mean? • Direction sensing refers to the ability of an instrument or controller to determine the direction of rotation of a shaft/motor by looking at the pulses coming from the encoder. The encoder output must be a two-phase type, quadrature with one phase 90 out of phase with the other. • How many pulses per revolution (PPR) should I specify? • That is very much dependent upon the application. • When interfacing an encoder to a drive for speed feedback, the driv
