Absolute Position Detection System; Outline; Features; Restrictions - Mitsubishi Electric MR-J2S-A 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 programmable 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
Current
position
data
I/O module
Servo motor

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/position).
(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) or an absolute position counter warning
(AL.E3) has occurred, always perform home position setting again. Not doing so
may cause unexpected operation.
POINT
When configuring an absolute position detection system using the QD75P/D
PLC, refer to the Type QD75P/QD75D Positioning Module User's Manual
(SH (NA) 080058).
Pulse train
(command)
Home position data
EEPROM memory
Backed up in the
case of power failure
Input
Output
Battery
1 pulse/rev Accumulative
revolution counter
Super capacitor
Within-one-revolution counter
(Position detector)
15 - 1
WWW.NNC.IR
Servo amplifier
Current
LSO
position
data
1XO
LS
Detecting the Detecting the
number of position within
revolutions one revolution
MR-BAT
1X
High speed serial
communication