Counters (C) - Mitsubishi Electric MELSEC-Q Series User Manual

10 DEVICES

10.2.11 Counters (C)

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Counters are "up counter" types, with the contact being switched ON when the count
value equals the setting value (count-out condition).
There are two counter types: counters which count the number of input condition start-
ups (leading edges) in sequence program, and counters which count the number of
interrupt factor occurrences.
Counters
(1) Definition
A counter is a device which counts the number of input condition leading edges
in sequence program.
(2) Count processing
A counter is a device which counts the number of input condition leading edges
in sequence program.
(a) When and OUT C
processing occurs: coil ON/OFF, present value update (count value + 1),
and contact ON/OFF.
Counter present value update and contact ON/OFF processing do not
occur at END processing.
[Ladder example]
X0
[Processing at OUT C0 Instruction (X0: OFF to ON)]
END
Sequence
program
(b) The present value update (count value + 1) occurs at the leading edge
(OFF to ON) of the OUT C
The present value is not updated in the following OUT C
statuses: OFF, ON to ON, ON to OFF
[Ladder example]
X0
[Present value update timing]
Sequence
program
OFF
X0
C0 coil OFF
instruction is executed, the following counter
K10
C0
OUT C0
instruction.
K10
C0
END OUT C0 END
ON
ON
Present value update
MELSEC-Q
END
Processing content
Coil ON/OFF
Present value update
Contact ON/OFF
instruction
OUT C0 END OUT C0
Present value update
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