MITSUBISHI ELECTRIC Merservo MR-J2S- B - Manual (Page 224)

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13. ABSOLUTE POSITION DETECTION SYSTEM
13. ABSOLUTE POSITION DETECTION SYSTEM
CAUTION
If an absolute position erase alarm (25) or an absolute position counter warning
(E3) has occurred, always perform home position setting again. Not doing so can
cause runaway.
13.1 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 servo system controller power is on or off.
Therefore, once home position return is made 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.
Servo system controller
Current
position
Home position data
LS0
CYC0
Servo amplifier
Position data
MR-BAT Battery
Detecting
the number
of revolutions Detecting the
position within
one revolution
P
o
sit
ion
c
ont
rol
speed cont
ro
l
High speed serial
communication
Servo motor
1 pulse/rev accumulative revolution counter
Super capacitor
Within one-revolution counter