Mitsubishi Electronics QD75P, QD75D user manual Incremental Encoder

APPENDICES

MELSEC-Q

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 signal slit	B signal slit
		Light-emitting diode
Slit disk	A
	Z	B
Phototransistor		Zero signal slit
Rotating axis		1 pitch

A

14 pitch

B

1 pulse per axis rotation

Zero signal

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.

Stop	No.1	No.2	No.3
			0
			Left
0	0
	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.

Appendix - 78