10 - 24 10 - 24
MELSEC-Q
10 DEVICES
10.2.11 Counters (C)
Counters are "up-timing" types, with the contact being switched ON when the count
value equals the set value (count-out condition).
There are two counter types: counters which count the number of input condition start-
ups (leading edges) in sequence programs, 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 programs.
(2) Count processing
(a) When and OUT C instruction is executed, the following counter
processing occurs: coil ON/OFF, current value update (count value + 1),
and contact ON/OFF.
Counter current value update and contact ON/OFF processing are not
performed at END processing.
Processing content
Coil ON/OFF
Current value update
Contact ON/OFF
X0
C0
K10
[Ladder example]
Sequence
program
END OUT C0 END
[Processing at OUT C0 Instruction (X0: OFF to ON)]
(b) The current value update (count value + 1) is performed at the leading edge
(OFF to ON) of the OUT C
instruction.
The current value is not updated in the following OUT C
instruction
statuses: OFF, ON to ON, ON to OFF
X0
C0
K10
[Ladder example]
X0
OFF
OFF
ON
ON
[Current value update timing]
END END ENDOUT C0 OUT C0 OUT C0
Current value update Current value update
Sequence
program
C0 coil
To Next Page
Loading...
