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Chapter 5 Instruction Specifications
5-34
Item number
Basic instructions-25, 26
Name
Up (CTU n) and down (CTD n) of up/down counter
(UP/DOWN COUNTER)
Ladder format Condition code
Processing time (µs)
Remark
R7F4 R7F3 R7F2 R7F1 R7F0
Average Maximum
DER ERR SD V C Upper case: CTU
CTD n
CTU n s
zzzzz 1.4
Lower case: CTD
Instruction format Number of steps
OUT CTU n s Condition Steps
OUT CTD n CTU 5 1.4
CTD 3
Bit Word Double word
Usable I/O
XY
R,
M
TD, SS,
CU, CT WX WY
WR,
WM TC DX DY
DR,
DM
Constant
Other
n Counter number { 0 to 255 (Decimal)
sSet value {{{ {1 to 65535 (Decimal)
Function
• For the UP counter, increments the progress value by 1 each time the leading edge of the startup condition is detected, while
it decrements the progress value by 1 for the DOWN counter. The coil switches on when the progress value is greater than
or equal to the set value and switches off when the progress value is less than the set value. When the counter clear CL n
switches on, the progress value is cleared to 0 and the coil switches off.
• The progress value is set in TC n, and the value will be in the range of 0 to 65535 (decimal).
• If the progress value is updated during RUN, the operation will be performed using the new progress value at that point.
• If an I/O is set for the set value, the set value can be changed during operation by changing the I/O value, since the set values
are updated during each scan.
Notes
• A maximum of 256 points can be used for the timers and counters TD, SS, CU, CTU and CTD in total.
• The timer numbers and counter numbers cannot be overlapped.
• The numbers for the UP coil and DOWN coil must be the same.
• While the counter clear CL n is on, the rise of startup condition is ignored.
• Since the startup condition of the counter is edge detection, the condition for one scan may not be detected during the first
scan after RUN starts.
• If the set value is set to “0”, it is regarded as a coil that is always on and controlled by the CL n.
OUT CTU n s
OUT CTD n