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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
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.
[Ladder example]
[Processing at OUT C0 Instruction (X0: OFF to ON)]
(b) Current value update (count value + 1)
The current value is updated (count value + 1) at the leading edge (
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.
[Ladder example]
X0
[Current value update timing]
Sequence
program
X0
Coil C0
instruction is executed
X0
END
Sequence
program
Figure 9.29 Execution and processing of the OUT C
K10
CO
END
OUT C0
ON
OFF
ON
OFF
Current value
update
Figure 9.30 Current value update timing
K10
C0
OUT C0
END
Processing
Coil ON/OFF
Current value update
Contact ON
instruction
END
OUT C0
END
CHAPTER9 DEVICES
of the
OFFŮON)
OUT C
OUT C0
Current value
update
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