Number Of Pulses/Travel Value Per Rotation - Mitsubishi Electric MELSEC Q Series Programming Manual

4 PARAMETERS FOR POSITIONING CONTROL

4.2.1 Number of pulses/travel value per rotation

The "Electronic gear function" adjusts the actual machine movement amount and
number of pulse output to servo amplifier according to the parameter set in the Motion
CPU.
It is defined by the "Number of pulses per rotation" and "Travel value per revolution".
POINTS
(1) The mechanical system error of the command travel value and real travel
value is rectified by adjustment the "electronic gear".
(2) The value of less than 1 pulse that cannot be execute an output when the
machine travels is incremented in the Motion CPU, and a total incremented
output is performed when the total incremented value becomes more than 1
pulse.
(3) The total incremented value of less than 1 pulse that cannot be execute an
output is cleared and it is referred to as "0" at the home position return
completion, current value change completion, speed-switching control start
(except the feed current value update) and fixed-pitch feed control start. (When
the total incremented value is cleared, the error occurs to the feed machine
value only a part to have been cleared.)
(4) Set the electronic gear within the following range.
0.001 
(1) Number of pulses/travel value per rotation
Number of pulses (AP)/travel value (AL) per rotation is an item which determines
how many rotations (number of pulses per rotation) of the servo motor in order to
make it a machine as the travel value ordered by the program.
The position control toward the servo motor is controlled with the number of
feedback pulses of the encoder connected to the servo motor in the servo
amplifier.
The control content of the Motion CPU is shown below.
Motion CPU
Command Control AP
value units AL
Fig. 4.1 Control content of the Motion CPU
For example, suppose that the servo motor was connected to the ball screw.
Because the travel value ( S) of machine per motor rotation is [mm] / [inch] unit,
the travel value (positioning address) set in the program is commanded in [mm] /
[inch] unit. However, the servo motor is positioning controlled by the servo
amplifier in pulse unit.
Number of pulses per rotation (AP)
Travel value per rotation (AL)
pulse
pulse Servo amplifier
pulse
Feedback pulse
4 - 3
 20000
Machine
Reduction gear
M
ENC