10
DEVICE EXPLANATION
10
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10.2 Internal User Devices
10.2.11 Counter (C)
To prevent the above, it is recommended to insert the N/C contact of the OUT
C0 instruction as the execution condition of the RST C0 instruction so that the
coil of C0 does not turn OFF while the execution condition (M0) of the OUT C0
instruction is ON.
(d) Maximum counting speed
The counter can count only when the input condition ON/OFF time is longer than
the execution interval of the corresponding OUT C instruction.
The maximum counting speed is calculated by the following expression:
* 1 : The "duty" is the count input signal's ON-OFF time ratio expressed as a percentage value.
Figure 10.33 Current value update timing
Figure 10.34 Counter resetting ladder example (recommended example)
n: Duty(%)
*1
T: Execution interval of the OUT C instruction (sec)
Figure 10.35 Duty ratio
M0
OFF
OFF
ON
RST C0
OUT C0
END
RST C0
OFF
RST C0
OUT C0
END
END
ON
Sequence
program
Coil of C0
Current value update
& contact ON
Coil of C0 OFF
Current value is updated
since coil of C0 turns
from OFF to ON.
Count value cleared & contact OFF
C0
RST
C0
M0
C0
K10
M0
[Modified ladder example]
n
100
T
Maximum counting
speed (Cmax)
[times/s]
1
=
OFF
ON
T1
T2
T2
T1
When T1 T2, n=
100%
100%
When T1 T2, n=
T1+T2
T1+T2
Count input signal
