CTUD

Counts (integers) from 0 up to a given value in increments of 1 or from a given value down to 0 in increments of 1.

IMPORTANT: The CTUD block does not detect the rising edges and falling edges of the counting inputs (CU and CD). The block must be associated with an R_TRIG or F_TRIG block to create a pulse counter.

Arguments
CU	BOOL	Up-counting (when CU is TRUE)
CD	BOOL	Down-counting (when CD is TRUE)
RESET	BOOL	Reset command (dominant) (CV = 0 when RESET is TRUE)
LOAD	BOOL	Load command (CV = PV when LOAD is TRUE)
PV	DINT	Programmed maximum value
QU	BOOL	Overflow: TRUE when CV >= PV
QD	BOOL	Underflow: TRUE when CV <= 0
CV	DINT	Counter result

Example

(* FBD program using the CTUD block *)

(* ST Equivalence: We suppose R_TRIG1 and R_TRIG2 are two instances of R_TRIG block and CTUD1 is an instance of CTUD block*)

R_TRIG1(add_elt);

R_TRIG2(sub_elt);

CTUD1(R_TRIG1.Q, R_TRIG2.Q, reset_cmd, load_cmd,100);

full := CTUD1.QU;

empty := CTUD1.QD;

nb_elt := CTUD1.CV;

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