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CTU Count Up Counter |
  
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CTU Count Up Counter |
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Block for gradual count of input pulses.
Ladder Representation
Block Structure
Variable Type |
Name |
Data Type |
Description |
VAR_INPUT |
CU |
BOOL |
Pulse identifier |
R |
BOOL |
Loads the zero value in CV |
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PV |
WORD UINT |
Maximum count value |
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VAR_OUTPUT |
Q |
BOOL |
Counter overrun flag |
CV |
WORD UINT |
Current count value |
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VAR |
CTU_INST_0 |
CTU |
Instance of access to block structure |
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NOTE!
Some devices allow you to configure user parameters, but these need to be configured for use in the fields PV and CV, where it is necessary to select a compatible data type (WORD or UINT). For more information refer to the corresponding topic. |
Operation
When this block identifies a leading edge in CD, it increments the CV variable until it is equal to PV. While CV equals PV, the output Q remains at TRUE level. By detecting high-level R, the block loads the zero value in CV.
Block Flowchart
Operation Diagram
Example in Ladder
The above example shows the initial conditions of routine. Since CV has a lower value than of PV, the Q output is disabled.
At each leading edge identified in CU, the value of CV is incremented until it reaches the PV value, when the Q output is enabled.
By identifying TRUE level in R, the block loads the zero value to CV. Since this value is lower than of PV, the Q output is disabled.
Example in ST
The example below displays the instructions for applying the example above in the ST language.
VAR PRESET : UINT := 30; COUNT : UINT; CTU_INST_0 : FB_CTU; END_VAR
CTU_INST_0.CU := DI1; CTU_INST_0(R:=DI2, PV:=PRESET); COUNT := CTU_INST_0.CV; DO1 := CTU_INST_0.Q;
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