User`s manual

151
CHAPTER 4 FUNCTION
4
4.14 Rotation Speed Measurement Function
(4) Required pulse speed (minimum)
The rotation speed, which is calculated from the count value per a unit of time, should be the value with which the
calculated count value becomes an integer number. Therefore, with the pulse speed lower than the one in the
following table, the rotation speed cannot be measured correctly.
For measurement, input the pulse with the speed shown below or higher.
In case a unit of time is 0.01s, the number of pulses per rotation is 60, and the pulse input speed is 1234pps,
the value of the measured rotation speed becomes 1200r/min or 1300r/min.
By doing the moving average count, the fluctuation of the measured values can be lowered.
(5) Moving average count
When the rotation speed measurement function is used, the fluctuation of the measured values of the rotation
speed can be lowered by doing the moving average count.
The number of the moving average count is set to CH1 Moving average count (rotation speed measurement)
(Un\G1151).
After the specified number of counts are done, the average of the measured values of the rotation speed is stored
in CH1 Measured rotation speed value (Un\G1182, Un\G1183).
In case the number of moving average count is set to 3
A unit of time Required pulse speed (minimum)
1s 1pps
0.1s 10pps
0.01s 100pps
Setting item Setting contents Reference
CH1 Moving average count (rotation speed
measurement) (Un\G1151)
Set the number of moving average count in the
range of 1 to 100.
When 1 (default value) is set, the operation is
performed with the moving average count regarded
as not being done.
Page 82, Section 3.4.2 (48)
Ex.
Ex.
CH1 Count enable command
(Y06)
Rotation speed
10000
T
1)
2)
3) 4)
5)
T
5000
0 Time
T: Time unit
1st storage
1st storage = 1)+2)+3)/3
2nd storage = 2)+3)+4)/3
3rd storage =3)+4)+5)/3
Buffer memory
CH1 Measured rotation
speed value
(Un\G1182, Un\G1183)
2nd storage
3rd storage