YASKAWA MOTIONPACK-110 Descriptive Information page 248

12.1.4 SELECTION OF DETECTOR
D In a machine configuration as shown in Fig. 12.1, the number of PG output pulses required
(Fpc) is given by
1 P
Fp_ = 7- x _o • N ............................................................... (10)
Since the pulses from PG are multipliedby 4 internally in the case of Motionpack-ll0, itis
necessary to multiply itby a coefficient of 1/4.
For example, ifdetectionresolution_ o = 0.001[mm/pulse], ballscrew pitch
P = 6 [mm], and reductionratioI/N = I/2,the number of PG output pulses,Fpc, is given
by
1 6 - 750 (pulses/rev)
F_c = _- x 0.001x2
D As the detector, a feedback unit consisting of PG (for detecting position) and
tachometer- generator (for detecting speed) is installed at the side opposite the load of the
motor.
The number of PG output pulses available from YASKAWA is shown in Table 12.1
foryourselection.
If the number of pulses of PG determined from equation (10) is other then those shown
in Table 9.1, then it is necessary to select a PG having the number of output pulses larger
than the calculated value of FaG and then correct it by the setting of special parameter posi-
tion command unit of the Motionpack-ll0. Refer to Par. 5.4 "SPECIAL PARAMETERS".
For instance, if _ o = 0.001, P = 6 and 1/N = 5/7 in Fig. 12.1.
Fpc 1 6
= T × 0.001×7/5 - 1071.428-.-
D '
In this case, 2000 pulses may be selected as encoder of the number of output pulses
larger than 1071.4, then the following calculations may be made as parameter of position
command unit.
B Detection side (Number of encoder output pulses) × 4
A Ballscrew side Pitch of ball screw
1
Detection resolution ×
Reduction ratio
2000 × 4 28
6 15
7
0.001 x-- "
5
D Then, 3137469 of 28/15 × 16777216 = 31317469.87 and the integer portion 8987794 of
15/28 x 16777216 = 8987794.286 should be set as parameter.
As the type of PG pulse output, 5 VDC line driver method or 12 VDC transistor
output should be used. (5 VDC transistor output cannot be used.)
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