Mitsubishi Electronics QD75D Rotary encoder, Linear encoder Appendix, For the main For the zero

APPENDICES

MELSEC-Q

DROOP PULSE

Because of inertia (GD2) in the machine, it will lag behind and not be able to track if the positioning module speed commands are issued in their normal state.

Thus, for a servomotor, a method is used in which the speed command pulses are delayed by accumulation in a deviation counter. These accumulated pulses are called the droop pulse.

The deviation counter emits all pulses and returns to 0 when the machine stops.

1,000	200 pulses	800
pulses	accumulate	pulses	D/A	Voltage
	in the
	counter

ELECTRONIC GEAR

This function electrically increases/decreases the command pulses from the pulse command module by 1/50 to 50-fold. Thus, the positioning speed and movement amount can be controlled by the electronic gear ratio magnification.

EMERGENCY STOP

Emergency stops cannot be carried out by the QD75, so a method of shutting OFF the servo side power supply from outside the PLC, etc., must be considered.

DWELL TIME

This is the time taken immediately after the positioning is completed to adjust for the droop pulses in the deviation counter. The positioning will not be accurate if this time is too short.

DYNAMIC BRAKE

When protection circuits operate due to power failures, emergency stops (EMG signal) etc., this function is used to short-circuit between servomotor terminals via a resistor, thermally consume the rotation energy, and cause a sudden stop without allowing coasting of the motor.

Braking power is generated by electromagnetic brakes only when running motors with which a large brake torque can be obtained. Because electromagnetic brakes have no holding power, they are used in combination with mechanical brakes to prevent dropping of the vertical axis.

ELECTROMAGNETIC BRAKE

This function is supplied on motors with electromagnetic brakes. Electromagnetic brakes are used to prevent slipping during power failures and faults when driving a vertical axis, or as a protective function when the machine is stopped.

These brakes are activated when not excited.

ENCODER

This device turns the input data into a binary code of 1 (ON) and 0 (OFF). A type of pulse generator.

			For the main For the zero
			signal	point signal
Ball bearing
					Code disk
		Z
Input axis
	A		B
Photoreceptor				Index	Light source
(phototransistor)				scale	(light-emitting diode)
			Rotary encoder
Light source
(LED)	Collimator lens
Main scale					b
					Photoreceptor
					(photodiode)
			a		a
Reference
			b	z
zero point
		Index

scale

Linear encoder

Appendix - 75