Mitsubishi Electric MELSEC FX3U Programming Manual page 115

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
• The current value increases or decreases without regard to the operation of the output contact. When a
counter executes up-count from "+2,147,483,647", the counter value becomes "−2,147,483,648". In the
same way, when a counter executes down-count from "−2,147,483,648", the counter value becomes
"+2,147,483,647". (This type of counter is called a ring counter.)
• When the reset input X011 turns ON and RST instruction is executed, the current value of the counter is
reset to "0" and the output contact is restored.
• In a latch type high speed counter, the current value, output contact operation and reset status of the
counter are latched (battery backed) by the backup battery built in the PLC.
2. 1-phase 2-count input
These counters are 32-bit binary bi-directional counters, and the operation of the output contact for the
current value is equivalent to that in 1-phase 1-count input type high speed counters described above.
X011
RST
X012
C246
X011
RST
X012
C249
3. 2-phase 2-count input
These counters are 32-bit binary bi-directional counters, and the operation of the output contact for the
current value is equivalent to that in 1-phase high speed counters described above.
X011
RST
X012
C251
C251
Y002
M8251
Y003
X011
RST
X012
C254
C254
Y004
M8254
Y005
• While X012 is ON, C246 executes up-count when the input
X000 turns from OFF to ON, and executes down-count when
C246
the input X001 turns from OFF to ON.
• The up/down-count operation of C246 to C250 can be checked
D2(D3)
with M8246 to M8250.
ON status: Down-counting
Set value is (D3,D2)
OFF status: Up-counting
• While X012 is ON, C249 immediately starts counting when the
input X006 turns ON.
C249
The up-count input is X000, and the down-count input is X001.
• A high speed counter can be reset by X011 in a sequence as
K1234
shown in the figure, but C249 is immediately reset without any
program when X002 is closed. So a program with X011 is not
necessary.
• The up/down-count operation of C246 to C250 can be checked
with M8246 to M8250.
ON status: Down-counting
OFF status: Up-counting
• While X012 is ON, C251 counts the operation of the inputs
X000 (A phase) and X001 (B phase) as interrupt.
C251
When X011 turns ON a RST instruction is executed and C251
is reset.
K1234
• When the current value becomes equivalent to or larger than
the set value, Y002 turns ON. When the current value becomes
equivalent to or smaller than the set value, Y002 turns OFF.
• Y003 turns ON (for down-count) or OFF (for up-count)
according to the counting direction.
• When X006 turns ON while X012 is ON, C254 immediately
C254 starts counting. Its counting inputs are X000 (A phase) and
X001 (B phase).
• In addition to reset by X011 in a sequence, C254 is reset
D0(D1)
immediately when X002 turns ON.
• When the current value becomes equivalent to or larger than
the set value (D1, D0), Y004 turns ON. When the current value
becomes equivalent to or smaller than the set value, Y004 turns
OFF.
• Y005 turns ON (for down-count) or OFF (for up-count)
according to the counting direction.
4.7 High Speed Counter [C] (FX3U/FX3UC PLC)
4 Devices in Detail
1
2
3
4
5
6
7
8
9
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