6-8
Section
Z-phase Margin
154
6-8
Z-phase Margin
6-8-1 Description
Although there will be some variations for different settings, the PCU origin
search basically works by stopping pulse output with the first encoder Z-phase
after confirming ON/OFF for the origin proximity signal, outputting error counter
reset, and determining that position as the origin.
In cases where the time (distance) from when the origin proximity signal chan-
ges from OFF to ON until the first Z-phase is detected is extremely short or is
almost the same as the time taken for one rotation, the position at which the
Z-phase is detected may be displaced by one phase due to discrepancies in the
ON response of the origin proximity sensor or the servo drive speed.
This displacement is avoided by confirming the “Z-phase margin.” The Z-phase
margin indicates in pulses the amount by which the motor rotated during the time
from when the origin proximity signal changed from ON to OFF until the Z-phase
was detected. If this value is close to 0 or close to one motor rotation, there is a
possibility of origin displacement during origin search. A simple way of reducing
the probability of this is to adjust the motor’s mounting angle and the origin prox-
imity sensor’s mounting position so that this value is approximately half a rota-
tion.
Origin Search Operation
Motor rotation
Origin proximity signal
Z-phase
Time
This distance is the Z-phase margin.
6-8-2 Calculating the Z-phase Margin (Example)
One way of obtaining the Z-phase margin is to, after origin search, perform jog-
ging in the opposite direction to origin search, stop operation at the point where
the origin proximity signal changes from OFF to ON, and read the value of the
present position at that point. The value of this present position will be equal to
the Z-phase margin. If the speed at the point where the origin proximity signal
changes from OFF to ON is fast, there will be some inaccuracy in the value read
for the Z-phase margin. Try to reduce the speed of the jog feeding in the neigh-
borhood of the point where the origin proximity signal changes from OFF to ON.
By adjusting mounting positions and angles so that this position corresponds to
approximately half the distance moved for one rotation of the motor.
Summary of Contents for CS1W-NC113 - REV 02-2008
Page 1: ...CS1W NC113 213 413 133 233 433 Position Control Units ...
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