Specifications

App - 36
Appendix 8 Glossary of MELSEC Positioning Related Terms
A
ABSOLUTE ENCODER
A detector that enables the angle data within 1
motor rotation to be output to an external
destination. Absolute encoders are generally able
to output 360° in 8 to 12 bits.
Incremental encoders have a disadvantage in tha
t
the axis position is lost when a power failure
occurs. On the other hand, with absolute encoders,
the axis position is not lost even when a powe
r
failure occurs.
Various codes such as a binary code and BCD
code can be output.
A
bsolute encoders are more
expensive, more accurate, and larger than
incremental encoders. Refer to "ENCODER".
Slit disk
Phototransistor
Fixed sli
t
Light-emitting diode
Rotating axis
Binary code
2
2
2
2
0
1
3
4
2
4
2
3
2
2
2
1
2
0
ABSOLUTE POSITION DETECTION SYSTEM
In the absolute position detection system, once
OPR is carried out at the system startup, the
system stores the machine position in the memor
y
and retains the current position even when the
power is turned OFF. Mechanical deviation will be
compensated, so that OPR is not required after the
power is turned ON next time. This system mus
t
have a motor with an absolute position detecto
r
and a servo amplifier and positioning module
compatible with the absolute position detection
system.
ABSOLUTE SYSTEM
One of systems for expressing a positioning
address.
Absolute address system.
This system uses 0 as a reference, and expresses
the address as the distance from 0. The direction
is automatically determined, even when it is no
t
designated. The other address system is the
increment system.
No.10 No.2 No.3
AUTOMATIC TRAPEZOIDAL
ACCELERATION/DECELERATION
An operation in which a graph of the time and
speed takes a trapezoidal shape.
Speed
Acceleration
Time
Deceleration
C
COMPOSITE SPEED
Movement speed of the control target during
interpolation operations.
Composite speed
Y axis speed
X axis speed
CREEP SPEED
Very slow speed at which a machine moves.
It is difficult for the machine to stop suddenly when
running at high speed, so the movement must firs
t
be changed to the creep speed before stopping.
CURRENT FEED VALUE
The OP address at completion of machine OPR is
stored.
The position currently being executed is stored.
This value changes when the current value is
changed.