CTUD (FB)

FUNCTION_BLOCK CTUD

Increments and decrements a given value

Note

Datatype WORD, which is used for PV in CODESYS, does not match the IEC standard, which for PV defines datatype INT.

(* Example declaration *)
CTUDInst : CUTD ;

(* Example in ST *)
CTUDInst(CU := VarBOOL1, CD:= VarBOOL2, RESET := VarBOOL3, LOAD:=VarBOOL4 , PV:= VarWORD1);

VarBOOL5 := CTUDInst.QU ;
VarBOOL6 := CTUDInst.QD ;
VarWORD2 := CTUDInst.CV ;

InOut:

Scope	Name	Type	Comment
Input	CU	BOOL	Rising edge: Incrementing CV by one
	CD	BOOL	Rising edge: Decrementing CV by one
	RESET	BOOL	TRUE: Reset CV to 0
	LOAD	BOOL	TRUE: Set CV to the start value PV
	PV	WORD	Start value for decrementing / upper limit for incrementing
Output	QU	BOOL	TRUE if CV >= PV
	QD	BOOL	TRUE if CV = 0
	CV	WORD	Current counter value