CHAPTER9 DEVICES
9
2
3
4
5
6
7
8
9.2 Internal User Device
9.2.11 Counter (C)
9 - 27
9.2.11 Counter (C)
(1) Definition
The counter (C) is a device that counts the number of rises for input conditions in sequence progra ms.
When the count value matches the set value, the counting stops and its contact is turned o n.
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