Mitsubishi Electronics QD75P, QD75D user manual Near-point dog of the OPR, Receiver

APPENDICES

MELSEC-Q

DECELERATION TIME

The parameter deceleration time is the same value as the acceleration time. Deceleration time refers to the time from the speed limit value to a stopped state, so it becomes proportionally shorter as the setting speed decreases.

Speed limit value

Setting speed

Speed 0 Time

Deceleration time

DEVIATION COUNTER

Deviation counters have the following two functions.

1)To count the command pulses issued from the QD75, and transmit the count value to the D/A converter.

2)To subtract the feedback pulses from the command pulses, and run the motor by the deviation value (droop pulse) of the command pulses and feedback pulses until the command pulses reaches 0.

Command
pulses	Deviation	D/A	Motor
	counter	convertor
		Feedback pulses	PLG Encoder

DIFFERENTIAL OUTPUT TYPE

This is one type of encoder feedback pulse output. When one signal is output with this method, a companion signal having the reverse polarity is simultaneously output. This method enables high-frequency transfer, and is resistant to noise, etc., so it is also used in high-speed signal transfer such as inputting and outputting of pulse trains. In general, the transmission side is called the driver, the reception side is called the receiver, and a dedicated IC is used.

Command	Servo amplifier
device

Driver Receiver

DIGITAL BUS CONNECTION

Commands are generally output from the positioning module to the servo amplifier as a pulse train. Recently, however, devices are being digitalized. Accompanying that, a connection method has appeared in which the bus lines of both the positioning module and the servo amplifier CPUs are connected. This has enabled the construction of higher- accuracy, higher-speed systems.

The MELSEC A70D, AD774M, A171SCPU, A273UCPU etc., models employ this digital bus connection.

DOG SIGNAL

The near-point dog of the OPR.

DRIVE UNIT

The commands output from the positioning module are low-voltage, low-current commands with insufficient energy to run the motor.

The drive unit increases the width of these commands so the motor can be run. It is an accessory on servomotors and stepping motors. Also called a servo amplifier.

Positioning	Drive	Motor
module	unit

Power supply

DRIVE UNIT READY

This signal is output when the drive unit for the motor is in a READY state.

This signal remains OFF when the drive unit power is OFF, or during faults, etc.

Appendix - 74