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14. ABSOLUTE POSITION DETECTION SYSTEM
14. ABSOLUTE POSITION DETECTION SYSTEM
CAUTION
If an absolute position erase (AL.25) or absolute position counter warning (AL.E3)
has occurred, always perform home position setting again. Not doing so can cause
runaway. Not doing so may cause unexpected operation.
POINT
If the encoder cable is disconnected, absolute position data will be lost in the
following servo motor series. HF-MP, HF-KP, HF-SP, HC-RP, HC-UP, HC-LP,
and HA-LP. After disconnecting the encoder cable, always execute home
position setting and then positioning operation.
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).
14.1 Outline
14.1.1 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.
Current
position
data
LSO
1XO
EEP-ROM memory
Backed up in the
case of power failure
Pulse train
(command)
Input
Output
I/O module
Positioning module
General purpose programmable
controller
CPU
Current
position
data
Changing the
current position
data
Servo motor
1 pulse/rev Accumulative
Within-one-revolution counter
Home position date
LS
Detecting the
number of
revolutions
1X
Detecting the
position within
one revolution
Battery
Position control
Speed control
High speed serial
communication
Position detector
MR-J3BAT
Servo amplifier
