MITSUBISHI ELECTRIC Mitsubishi Programmable Logic Controller QD75D - Manual (Page 714)

Appendix - 72
MELSEC-Q
APPENDICES
BIPOLAR DRIVE CONSTANT-CURRENT
SYSTEM
This is one system for driving a stepping
motor. In this method, the orientation of the
excitation current flowing to the stator coil is
reversed, and the excitation current direction is
in both the positive and negative direction.
This enables the motor coil to be used
effectively, and a large output torque can be
obtained at low speeds.
Bipolar drive basic circuit (bridge method)
A phase
BUFFER MEMORY
Memory used to temporarily store data. Before
writing external data to the PLC CPU data
memory, it is first temporarily stored in the
buffer memory to be used for operation by the
program. The buffer memory is used by the
positioning module because the latest data
can be read and written.
PLC CPU
Data
memory
Bus
Positioning module
Buffer
memory
External
data
Data is written/read
using the following
commands:
Write : TO
Read : FROM
BUSY
The device is doing some other work. It is in a
positioning operation or in dwell time.
CCW (Counterclockwise)
Rotation in the counterclockwise direction. In
the motor, this is determined looking from the
shaft end side. Also refer to "CW".
CHANGE signal
The CHANGE signal is an external signal used
to switch the speed-position control from the
speed control being executed to position
control.
CIRCULAR INTERPOLATION
Automatic operation in which the machine path
makes a circle when positioning is carried out
by simultaneously operating both the
longitudinal feed and latitudinal feed motors.
The normal unit is 90ø. Round shapes can be
created with this type of interpolation, and
obstacles in the machine path can also be
avoided. Refer to the terms "INTERPOLATION
OPERATION" and "LINEAR
INTERPOLATION"
A B C D
Collision
Obstacle
COMMAND PULSE
Refer to term "FEEDBACK PULSE".
COMPOSITE SPEED
The movement speed for the target control
during interpolation operations.
Y axis
speed
Composite speed
X axis speed
CONTROL UNIT
This is one type of positioning reference data.
The unit to be used is designated as mm, inch,
degree, or pulse.