Mitsubishi QD75P1N - Page 561

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MELSEC-Q
12 CONTROL SUB FUNCTIONS
[2] Outline of absolute position detection data communication
As shown in Fig. 12.35 System block diagram, the detector comprises an
encoder for detecting its position in one rotation in addition to the A, B, Z phase
signal for position control in normal operation and a cumulative rotation counter
for detecting the number of rotations.
The absolute position detection system detects the absolute position of the
machine constantly and stores it with the backup of the battery irrespective of
whether the programmable controller system power is turned ON/OFF. Thus,
once the OP initial setting is carried out at the time of installation of the machine,
the OPR is not required even when the power is later turned ON. The restoration
can be carried out easily when an instantaneous power interruption or
emergency stop occurs.
In addition, because the absolute position data is backed up by a super
condenser built in the detector, the absolute position data will be stored for a
specified time even if the cable is disconnected or broken.
I/O module
Programmable controller system
Current feed value
Current
position
change
QD75QCPU
Output
Input
Servo amplifier
Position
control/
speed
control
Pulse train
command
OP data
Backup at
power OFF
LS0
1X0
1X
Detection of
position in one
rotation
LS
detection of
number of
rotations
Servomotor
Counter in one rotation
A.B.Z phase signal
Detector
1 pulse/rev cumulative rotation
counter
Super condenser
High-speed serial
communication
Battery
Current
position
Machine feed value
E PROM memory
2
Fig. 12.37 System block diagram