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Built-in Inputs
Procedure
1,2,3...
Restrictions
Specifications
Pulse Frequency Conversion
The frequency can be measured while a high-speed counter 0 comparison
operation is in progress. Frequency measurement can be performed at the
same time as functions such as the high-speed counter and pulse output with-
out affecting the performance of those functions.
1. High-speed Counter Enable/Disable Setting (Required)
Set the High-speed Counter 0 Enable/Disable setting to 1 or 2 (use high-
speed counter) in the PLC Setup.
2. Pulse Input Mode Setting (Required)
Set the High-speed Counter 0 Pulse Input Mode in the PLC Setup.
3. Counting Mode Setting (Required)
Set the High-speed Counter 0 Counting Mode in the PLC Setup.
If ring mode counting is selected, set the High-speed Counter 0 Ring
Counter Maximum Value (max. ring count) in the PLC Setup.
4. Reset Method Setting (Required)
Set the High-speed Counter 0 Reset Method in the PLC Setup.
5. PRV(881) Instruction Execution (Required)
N: Specify the high-speed counter number. (High-speed counter 0: #0010)
C: #0003 (Read frequency)
D: Destination word for frequency data
• The frequency measurement function can be used with high-speed
counter 0 only.
Item
Number of frequency
measurement inputs
Frequency measurement
range
Measurement method
Output data range
The pulse frequency input to high-speed counter 0 can be converted to a rota-
tional speed (r/min) or the PV of the counter can be converted to the total
number of rotations. The converted value is output as 8-digit hexadecimal.
This function is supported only for high-speed counter 0.
Frequency − Rotational Speed Conversion
The rotational speed in r/min is calculated from the pulse frequency input to
high-speed counter 0 and the number of pulses per rotation.
Counter PV − Total Number of Rotations Conversion
The total number of rotations is calculated from the present value of the
counter and the number of pulses per rotation.
Specifications
1 input (high-speed counter 0 only)
Differential phase inputs: 0 to 50 kHz
All other input modes: 0 to 100 kHz
Note If the frequency exceeds the maximum value, the maxi-
mum value will be stored.
Execution of the PRV(881) instruction
Units: Hz
Range:
Differential phase input: 0000 0000 to 0003 0D40 hex
All other input modes: 0000 0000 to 0001 86A0 hex
Section 6-1
139
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