Mitsubishi Electric MELSEC-L02SCPU User Manual page 230

(4) Measurement example
In this example, rotation speed is measured under the following conditions.
• Actual rotation speed: 1234r/min
• Rotation speed measurement unit time: 0.01s
• Rotation speed movement averaging processing count: 1 (The moving average processing is not
performed.)
• Number of pulses per rotation (pulse): 60pulses
(a) Count value per time unit
Count value per time unit for the actual rotation speed is calculated as follows using the formula in  Page
227, Section 8.6 (1) (b).
The count value should be an integer. For this reason, the count value in this example is 12 or 13 because the
numbers after the decimal point is accumulated within the module. When this count value is used in the formula
above, the following result can be acquired.
(b) Calculating frequency error (maximum)
Error (maximum) (r/min) = 1234(r/min)
228
1234(r/min)
=
Count value per unit time
Rotation speed measurement value (r/min) =
Rotation speed measurement value (r/min) = 1200(r/min) or 1300(r/min)
= 0.07404(r/min) + 100(r/min)
= 100.07404(r/min)
60 Count value per unit time
0.01(s) 60(pulse)
=
12.34
60 (12 or 13)
60(ppm)
+
1000000 0.01(s)
60
1 60(pulse)