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CHAPTER9 DEVICES
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9.2 Internal User Device
9.2.11 Counter (C)
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9.2.11 Counter (C)
(1) Definition
The counter (C) is a device that counts the number of rises for input conditions in sequence programs.
When the count value matches the set value, the counting stops and its contact is turned on.
The counter is of an incremental type.
(2) Counter types
Counters are mainly classified into the following two types.
• Counter that counts the number of rises for input conditions in sequence programs
• Interrupt counter that counts the number of interrupts occurred
(3) Counting
(a) When the OUT C instruction is executed
The coil of the counter is turned on/off, the current value is updated (the count value + 1), and the contact is
turned on.
In the END processing, the current counter value is not updated and the contact is not turned on.
(b) Current value update (count value + 1)
The current value is updated (count value + 1) at the leading edge (
OFF ON) of the OUT C
instruction.
The current value is not updated while the coil is off, or when it remains on or turns off from on by the OUT C
instruction.
Figure 9.30 Execution and processing of the OUT C instruction
Figure 9.31 Current value update timing
X0
C0
K10
END OUT C0 END
[Ladder example]
Sequence
program
[Processing at OUT C0 Instruction (X0: OFF to ON)]
Coil ON/OFF
Current value update
Contact ON
Processing
X0
C0
K10
X0
OFF
OFF
ON
ON
END END ENDOUT C0 OUT C0 OUT C0
[Ladder example]
[Current value update timing]
Sequence
program
Coil C0
Current value
update
Current value
update