YASKAWA Sigma-V Series User Manual page 342

9 Fully-closed Loop Control
9.1.6 Precautions When Using an External Incremental Encoder by Magnescale
When Passing 1st Zero Point in Reverse Direction and Returning after Power ON
After the power is turned on, the phase-C pulse (CN1-19, CN1-20) is not output when the external encoder
moves reverse and its head first passes the phase-C detection position. The phase-C pulse is output for the first
time when the external encoder moves forward and its head passes the detection position. After the detection
head of the encoder first passes the detection position in the forward direction, the phase-C pulse is output
when the head passes the position regardless of the direction of the encoder's movement.
Scale count-up direction
Phase-C detection position
Phase-C pulse output
The phase-C pulse is not output
when passing the detection position
in reverse direction first.
9-8
Power ON
The phase-C pulse is also output when passing this point in reverse,
because the SERVOPACK has recorded the position where the phase-C pulse was
originally output when first passing the position in the forward direction.
Rotation
Time