4 DEVICES
4.2 User Devices
63
4
Counter reset
Current value of counters is not cleared even if its coil input is turned OFF. To clear (reset) the current value of the counter and
turn the contact OFF, use the RST C instruction/RST LC instruction. The counter value is cleared and the contact is
turned OFF as soon as the RST C instruction is executed.
Precautions when performing counter reset
• When a counter is reset by the RST instruction, it cannot count until the RST instruction is set to OFF.
• When the counter is set as a latch device, the current value of a counter, output contact operation, and the reset image are
latched.
• If the ZRST instruction is used, the RST image of a counter is reset.
Execution
OFF
X0
ON
END RST C0 END RST C0 END RST C0
OFF
X0
Program
[Counter reset timing]
[Ladder example]
RST C0
Count value cleared,
the contact turned OFF
Count value cleared,
the contact turned OFF
RST C0
instruction
ON
OFF
Reset image
X0
Current value
of C0
1
2
3
The current value does not change
even if pulses are input because the
C0 reset instruction is valid.
C0 remains reset
"RST C0" is set to ON
because the contact turns ON.
X10
RST
C0
1
2
3
"RST C0" is set to OFF
because the contact turns OFF.
[Timing chart]
[Program example]
X10
RST C0
C0 is reset while X10 turns ON.
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