Mitsubishi Q00JCPU User Manual page 486

9
DEVICE EXPLANATION
9
9.2 Internal User Devices
- 35
9.2.11 Counter (C)
END
Sequence
program
ON
M0 OFF
Coil of C0
OFF
Current value update
& contact ON
RST C0 OFF
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.
Diagram 9.34 Counter resetting ladder example (recommended example)
(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
The maximum counting speed is calculated by the following expression:
Maximum counting
=
speed (Cmax)
100
* 1 : The "duty" is the count input signal's ON-OFF time ratio expressed as a percentage value.
When T1 T2, n=
When T1 T2, n=
Count input signal
OUT C0 RST C0
ON
Coil of C0 OFF
Count value cleared & contact OFF
Diagram 9.33 Current value update timing
[Modified ladder example]
M0
C0 M0
n: Duty(%)
n 1
[times/s]
T
T: Execution interval of the OUT C
T1
100%
T1+T2
T2
100%
T1+T2
T1
ON
OFF
Diagram 9.35 Duty ratio
END OUT C0 RST C0
Current value is updated
since coil of C0 turns
from OFF to ON.
K10
C0
RST C0
instruction.
*1
T2
END
instruction