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Counter instructions
CTU
The function block CTU (count up) allows you to program counting procedures.
Description
To add an enable input and enable output to the instruction, select [With EN/ENO] from the
"Instructions" pane (LD, FBD or IL editor). To reuse an instruction select "Recently used" from the
context menu or press <Ctrl>+<Shift>+<v> in the programming window.
For CTU declare the following:
CU
RESET (R)
PV
Q
CV
The names in brackets are the valid parameter names of the ST-editor.
PLC types
Availability of CTU (see page 1319)
Time chart
Data types
Data type
BOOL
INT
BOOL
INT
316
Up counter
clock generator
the value 1 is added to CV for each rising edge at CU, except when RESET is
set
reset
CV is reset to zero for each rising edge at RESET
set value
if PV (preset value) is reached, Q is set
signal output
is set if CV is greater than/equal to PV
current value
contains the addition result (CV = current value)
I/O
Function
input CU
detects rising edge, adds 1 to CV
input RESET
resets CV to 0 at rising edge
input PV
set value
output Q
set if CV >= PV
output CV
current value
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