
4.SERVO FUNCTION DETAILS B-65270EN/05
- 344 -
4.18.7 Position Feedback Switching Function
When the full preload function is enabled, low servo rigidity can result
in vibration, as shown in Fig. 4.18.7 (a), only in the case of driving by
the sub-axis. In such a case, stable operation can be achieved by using
the position feedback switching function.
01 2 3 4
−10
0
−80
−60
−40
−20
0
20
sec
Motor speed (− command)
01 2 3 4
−
20
0
20
40
60
80
100
sec
Motor speed (+ command)
Drive by the main motor Drive by the sub-motor
Fig. 4.18.7 (a) Motor speeds with plus-direction and minus-direction commands
#7 #6 #5 #4 #3 #2 #1 #0
1952 (FS15i)
PFBSW
2008 (FS30i, 16i)
PFBSW (#6) 1: Switches position feedback according to the direction of a torque
command.
0: Always uses main axis position feedback.
(Set this parameter for the main axis only.)
CAUTION
Always set this bit while the system is in the
emergency stop state. After rewriting this bit,
always turn the power to the NC off, then back on.
1737 (FS15i)
Position feedback switching time constant τ (JITEI)
2126 (FS30i, 16i)
Set this parameter for the main axis only. Set 0 for this parameter for
the sub-axis.
[Valid data range] 0 to 4096
[Method of setting] {1 - exp (-1 ms/τ)} × 4096
[Standard setting] 0
When τ = ∞ : Parameter = 0
When τ = 50 ms: Parameter = 81
When τ = 0: Parameter = 4096
NOTE
This parameter is valid only when PFBSWC = 1.