Mitsubishi Electric MELSEC-L LD75D, User Manual

Page: 779 / 818

777
APPENDICES
A
Appendix
8
ME
LSE
C
E
xplanat
ion
of
Pos
itioning T
e
rm
s
SLAVE AXIS
During interpolation operation, the positioning data is partially ignored on this side. This axis is moved by the
master axis data.
TURNTABLE
A rotating table, which is turned using power. The table is used divided from one 360

rotation into the required
locations for work.
The positioning control unit is "degree".
DYNAMIC BRAKE
When protection circuits operate due to power failures, emergency stops (EMG signal) etc., this function is used
to short-circuit between servomotor terminals via a resistor, thermally consume the rotation energy, and cause a
sudden stop without allowing coasting of the motor.
Braking power is generated by electromagnetic brakes only when running motors with which a large brake torque
can be obtained. Because electromagnetic brakes have no holding power, they are used in combination with
mechanical brakes to prevent dropping of the vertical axis.
DATA NO.
To carry out positioning to 2 or more addresses, each position is assigned a sequence No. such as No. 1, No. 2,
No. 3, etc. The positioning is then carried out following this sequence. The LD75 is capable of positioning up to
No. 600.
TEACHING
When the positioning address is uncertain, or gauging is required, this function is used by the user to search for
and teach the position to the machine.
For example, complex addresses such as drawings can be taught by tracing a model, and the positioning
operation can be reproduced.
DIGITAL BUS CONNECTION
Commands are generally output from the positioning module to the servo amplifier as a pulse train. Recently,
however, devices are being digitalized. Accompanying that, a connection method has appeared in which the bus
lines of both the positioning module and the servo amplifier CPUs are connected. This has enabled the
construction of higher-accuracy, higher-speed systems.
The MELSEC A70D, AD774M, A171SCPU, A273UCPU etc., models employ this digital bus connection.
DWELL TIME
This is the time taken immediately after the positioning is completed to adjust for the droop pulses in the
deviation counter. The positioning will not be accurate if this time is too short.
DRIVE UNIT
The commands output from the positioning module are low-voltage, low-current commands with insufficient
energy to run the motor.
The drive unit increases the width of these commands so the motor can be run. It is an accessory on
servomotors and stepping motors. Also called a servo amplifier.
DRIVE UNIT READY
This signal is output when the drive unit for the motor is in a READY state.
This signal remains OFF when the drive unit power is OFF, or during faults, etc.
TRACKING FUNCTION
In this function, positioning is carried out at a speed relative to a moving target object by inputting the movement
amount from an external encoder and adding it to the servo command value.
TORQUE RIPPLE Torque width variations, deviations in the torque.
TORQUE LOOP MODE
Also called the current loop mode.
Refer to the term "POSITION LOOP MODE".
Term Description
Rotated by the motor
30
°
No.1
No.2
No.3
No.4
No.5
No.6
Positioning
module
Drive
unit
Motor
Power supply