MITSUBISHI ELECTRIC Mitsubishi Programmable Logic Controller QD75D - Manual (Page 720)

Appendix - 78
MELSEC-Q
APPENDICES
INCREMENTAL ENCODER
A device that simply outputs ON/OFF pulses
by the rotation of the axis. 1-phase types
output only A pulses, and do not indicate the
axis rotation direction. 2-phase types output
both A and B pulse trains, and can judge the
rotation direction. The direction is judged to be
forward if the B pulse train turns ON when A is
ON, and judged to be reverse if A turns ON
when B is ON. There is also another type of
incremental encoder with a zero signal. The
most commonly used incremental encoders
output between 100 and 10,000 pulses per
axis rotation. Refer to "ENCODER".
A
B
A
Z
B
1
4
A signal slit
B signal slit
Slit disk
Light-emitting diode
Phototransistor Zero signal slit
Rotating axis 1 pitch
pitch
Zero signal
1 pulse per axis rotation
Output waveform 2-phase + OP output
INCREMENTAL SYSTEM
The current value is 0 in this system. Positions
are expressed by the designated direction and
distance of travel. Also called the relative
address system. This system is used in fixed-
feed, etc. Compare ABSOLUTE SYSTEM.
No.1 No.2 No.3
0
0 0
Stop
Left
Right Right No. 2 is several millimeters
to the right of No. 1.
INERTIA
The property of an object, when not being
affected by external forces, where it tries to
maintain its current condition. The inertia
moment.