Mitsubishi Electric MELSEC-L LD75P User Manual page 790

Term
EMERGENCY STOP
LOAD INERTIA RATIO
DEVIATION COUNTER
INTERPOLATION OPERATION
DROOP PULSE
ZERO SIGNAL
788
Emergency stops cannot be carried out by the LD75, so a method of shutting OFF the servo side power supply
from outside the programmable controller, etc., must be considered.
2 2
GDL /GDM
2
Refer to the term "GD ".
Deviation counters have the following two functions.
• To count the command pulses issued from the LD75, and transmit the count value to the D/A converter.
• To subtract the feedback pulses from the command pulses, and run the motor by the deviation value (droop
pulse) of the command pulses and feedback pulses until the command pulses reaches 0.
Command
pulses
Deviation
counter
Feedback pulses
The simultaneous operation of multiple motors to carry out a composite operation. Each motor can be freely set
with the positioning distance, acceleration/deceleration time, speed, and other factors, which are combined to
move a target in a straight line, circle, etc. Linear interpolation and circular interpolation are available. (The
circular interpolation uses two motors.)
Because of inertia (GD2) in the machine, it will lag behind and not be able to track if the positioning module
speed commands are issued in their normal state.
Thus, for a servomotor, a method is used in which the speed command pulses are delayed by accumulation in a
deviation counter. These accumulated pulses are called the droop pulse.
The deviation counter emits all pulses and returns to 0 when the machine stops.
1,000 800
200 pulses
pulses pulses
accumulate
in the
counter
This refers to PG0 of the pulse generator (encoder) (one detection per shaft rotation). It also called "Z phase".
Refer to the term "PULSE GENERATOR".
Description
D/A
Motor
convertor
PLG Encoder
D/A Voltage