Omron CJ1M-CPU21, Operation Manual

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Built-in Inputs Section 6-1
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.
Procedure
1,2,3... 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
Restrictions • The frequency measurement function can be used with high-speed
counter 0 only.
Specifications
Pulse Frequency Conversion
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.
Item Specifications
Number of frequency
measurement inputs 1 input (high-speed counter 0 only)
Frequency measurement
range 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.
Measurement method Execution of the PRV(881) instruction
Output data range Units: Hz
Range:
Differential phase input: 0000 0000 to 0003 0D40 hex
All other input modes: 0000 0000 to 0001 86A0 hex