CTUD / CTUDr

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Function Block - Up/down counter.

Inputs

Input	Data Type	Description
CD	BOOL	Enable counting. Counter is decreased on each call when CD is TRUE.
CU	BOOL	Enable counting. Counter is increased on each call when CU is TRUE.
LOAD	BOOL	Re-load command. Counter is set to PV when called with LOAD to TRUE.
PV	DINT	Programmed maximum value.
RESET	BOOL	Reset command. Counter is reset to 0 when called with RESET to TRUE.

Outputs

Output	Data Type	Description
CV	DINT	Current value of the counter.
QD	BOOL	TRUE when counter is empty (i.e., when CV = 0).
QU	BOOL	TRUE when counter is full (i.e., when CV = PV).

Remarks

The counter is empty (CV = 0) when the application starts.
The counter does not include a pulse detection for CU and CD inputs.
Use the f_trig or r_trig function blocks for counting pulses of CU or CD input signals.
CTDr, CTUr, and CTUDr function blocks operate exactly as other counters.
- Exception: All Boolean inputs (CU, CD, RESET, LOAD) have an implicit rising edge detection included.

FBD Language Example

FFLD Language Example

In the FFLD Language, CU is the input rung.
- The output rung is the QU output.

IL Language Example

Not available.

ST Language Example

(* MyCounter is a declared instance of CTUD function block. *)
MyCounter (CU, CD, RESET, LOAD, PV);
QU := MyCounter.QU;
QD := MyCounter.QD;
CV := MyCounter.CV;