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MELSEC-Q
12 CONTROL SUB FUNCTIONS
[1] Movement amount per pulse
"
Pr.2
No. of pulses per rotation (Ap)", "
Pr.3
Movement amount per rotation
(Al)", and "
Pr.4
Unit magnification (Am)" are the items for determining how
many rotations (equivalent to how many pulses) a motor should operate to move
a machine for movement amount set in a program.
The drive unit controls the motor with the pulse number.
The following shows the details of control of the QD75.
Command
value
Ap
Al Am
*2
Drive unit
QD75
Command
pulses
*1
Motor
Machine
Lead
Reduction gear
Worm gear
CPU module,
GX Configurator-QP
Electronic
gear
Rotating motor depending
on the number of pulses
Fig. 12.10 System using a ball screw
1: The upper limits of the command pulse frequency are as follows
• QD75D
N : 4Mpulse/s
• QD75D : 1Mpulse/s
• QD75P N/QD75P : 200kpulse/s
2: For a drive unit without electronic gear function, or when not using electronic gear
function, this value is 1 (single).
Consider a system with the motor connected to a ball screw, such as the figure
above.
1 is set to the electronic gear of the drive unit.
The movement amount of the machine is in mm or inch unit. Set the command
value in mm or inch units to the QD75 for the CPU module program.
The motor is controlled by the drive unit in pulse number units.
Consequently, since the command value in mm or inch units is converted to
pulse units, set Ap, Al, and Am so that the following relational expressions are
satisfied.
Number of pulses per rotation of motor = Ap
Movement amount per rotation of motor = Al
Am
In this case, the machine movement amount for the command 1 pulse output
from the QD75 is calculated by the following expression.
Al
Am
Movement amount per pulse (A) =
Ap
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