
B–63833EN–1/02
15. PMC CONTROL FUNCTION
891
Gears
↑
Motor
Axis
Detector
(a)
(b)
Speed command
Amplifier
↑
(a) The speed command for PMC axis control requires the
specification of the servo motor speed, not the feedrate along an
axis. To specify a feedrate along the axis when gears are used to
link the servo motor and axis, the feedrate must be converted to
a rotation speed of the servo motor speed. As the motor speed
must be specified with an integer, the converted speed is subject
to a round–off error.
(b) The minimum increment for specifying the motor speed is
calculated by the following formula and rounded to the nearest
integer:
Fmin +
P 2
15
1
1000
Fmin : Minimum increment
for the motor speed
P : Number of pulses per
rotation of the detector
for velocity feedback
Specify the speed command using the value calculated by the
following formula:
F +
N P 2
15
1
1000
F : Speed command value
(integer)
N : Servo motor speed
(min
–1
)
P : Number of detector
pulses issued per rotation
for velocity feedback
NOTE
In speed command mode, the speed after
acceleration/deceleration is specified to the servo control
unit. The loop gain for position control is invalid.
(16) When a torque control command (EC0g to EC6g: 11h) is specified
Specify the maximum speed in torque control mode, in min
–1
.
A servo alarm (No. 422) is issued if there is no object for which a
torque is to be generated or if the feedrate exceeds the specified value
while torque control is being applied.