4 PARAMETERS FOR POSITIONING CONTROL

4.2.1 Number of pulses/travel value per rotation

The "Electronic gear function" adjusts the pulse calculated and output by the parameter set in the Q173HCPU/Q172HCPU and the real travel value of machine.

It is defined by the "Number of pulses per rotation" and "Travel value per revolution".

POINTS

(1)The mechanical system error of the command travel value and real travel value is rectified by adjustment the "electronic gear".

(2)The value of less than 1 pulse that cannot be execute a pulse output when the machine travels is incremented in the Q173HCPU/Q172HCPU, and a total incremented pulse output is performed when the total incremented value becomes more than 1 pulse.

(3)The total incremented value of less than 1 pulse that cannot be execute a pulse output is cleared and it is referred to as "0" at the home position return completion, current value change completion, speed-switching control start (except the feed current value update) and fixed-pitch feed control start. (When the total incremented value is cleared, the error occurs to the feed machine value only a part to have been cleared.)

"Number of pulses/travel value per rotation" are shown below.

(1) Number of pulses/travel value per rotation

Number of pulses(AP)/travel value(AL) per rotation is an item which determines how many rotations (number of pulses per rotation) of the servomotor in order to make it a machine as the travel value ordered by the program.

The position control toward the servomotor is controlled with the number of feedback pulses of the encoder connected to the servomotor in the servo amplifier.

The control content of the Motion CPU is shown below.

Q173HCPU/Q172HCPU

 

 

 

 

 

 

 

PLS

Reduction gear

Machine

 

 

 

 

 

 

 

 

 

 

 

Command

 

Control

AP

 

 

Servo amplifier

 

 

 

 

 

PLS

M

 

 

 

 

 

 

 

 

 

 

 

 

value

 

units

AL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ENC

PLS

Feedback pulse

Fig. 4.1 Control content of the Motion CPU

For example, suppose that the servomotor was connected to the ball screw. Because the travel value (S) of machine per motor rotation is [mm] / [inch] unit, the travel value (positioning address) set in the program is commanded in [mm] / [inch] unit. However, the servomotor is positioning controlled by the servo amplifier in pulse unit.

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