Mitsubishi Electric FATEC MELSEC iQ-R Training Manual page 12

Simple transfer control can be achieved with programmable controllers using timers and limit
switches where high accuracy is not required as shown in previous page.
For positioning control or transfer control where high accuracy is required, the positioning
function of programmable controllers can be used to stop workpiece accurately at target
position with high repeatability and high reliability.
The stopping accuracy of the function can be controlled in the order of μm depending on the
equipment mechanism.
• For positioning control using the positioning function of programmable controllers, devices
appropriate to the control are required. The outline and functions of the devices are shown
below.
(1) Positioning controller (CPU module or positioning module)
(2) Driving amplifier or driver for transmitting commands from programmable controllers to
motor
(3) Servo motor or stepping motor capable of precisely detecting rotation angle
(1) Positioning controller
The CPU module or module serves as the positioning controller and
gives necessary information for positioning to the servo amplifier or
the stepping motor driver.
(2) Servo amplifier or the stepping motor driver
Based on the commands given by programmable controllers like
the rotation direction, rotating speed, rotation amount are transmitted
to the motor.
In which direction, forward or reverse... Rotation direction command
At what speed
To where
(3) Servo motor or stepping motor
The motor rotates in the specified direction at the specified speed and
stops at the specified position according to the command given by the
servo amplifier or stepping motor driver.
... Speed command
... Position command
1-2