Absolute Position Detection System; Outline; Features; Restrictions - Mitsubishi Electric MR-J2S-*A series Instruction Manual

15. ABSOLUTE POSITION DETECTION SYSTEM

15. ABSOLUTE POSITION DETECTION SYSTEM
CAUTION

15.1 Outline

15.1.1 Features

For normal operation, as shown below, the encoder consists of a detector designed to detect a position
within one revolution and a cumulative revolution counter designed to detect the number of revolutions.
The absolute position detection system always detects the absolute position of the machine and keeps it
battery-backed, independently of whether the general-purpose programming controller power is on or off.
Therefore, once the home position is defined at the time of machine installation, home position return is
not needed when power is switched on thereafter.
If a power failure or a fault occurs, restoration is easy.
Also, the absolute position data, which is battery-backed by the super capacitor in the encoder, can be
retained within the specified period (cumulative revolution counter value retaining time) if the cable is
unplugged or broken.
General purpose programmable
controller
CPU Positioning module
I/O module

15.1.2 Restrictions

The absolute position detection system cannot be configured under the following conditions. Test
operation cannot be performed in the absolute position detection system, either. To perform test
operation, choose incremental in parameter No.1.
(1) Speed control mode, torque control mode.
(2) Control switch-over mode (position/speed, speed/torque, torque/speed).
(3) Stroke-less coordinate system, e.g. rotary shaft, infinitely long positioning.
(4) Changing of electronic gear after home position setting.
(5) Use of alarm code output.
If an absolute position erase alarm (AL.25) has occurred, always perform home
position setting again. Not doing so can cause runaway.
Pulse train
(command)
Current
position
data
Input
Output
Servo motor
1 pulse/rev Accumulative
revolution counter
Within-one-revolution counter
A, B, Z phase signals
(Position detector)
Servo amplifier
Home position data
EEPROM memory
LSO
1XO
Backed up in the
case of power failure
Detecting the
number of
revolutions
Battery MR-BAT
Super capacitor
15 - 1
Current
position
data
LS 1X
Detecting the
position within
one revolution
High speed serial
communication