Transforming LD to ST programs

Note the following if you wish to transform your LD program to an ST program:

1. Network with normal output
LD program	ST program code	Remarks
	`Y0 := X0 AND X1 OR X2 AND NOT X3;`
Also possible:	`IF X0 AND X1 OR X2 AND NOT X3 THEN Y0:=TRUE; ELSE Y0:=FALSE; END_IF;`	Same behavior, but requires more resources. NOTE A WHILE loop would cause a scan time error and lead to a watchdog error.
2. Network with a set or reset output
LD program	ST program code
	`IF X0 AND X1 THEN Y0 := TRUE; END_IF; IF X2 AND NOT X3 THEN Y0 := FALSE; END_IF;`
3. Network with pulse flag (rising/falling edge)
LD program	ST program code	Remarks
	`(* rising edge ) IF X0 AND NOT X0_Old THEN Count:=Count+1; END_IF; X0_Old:=X0; ( falling edge *) IF NOT X1 AND X1_Old THEN Count:=Count-1; END_IF; X1_Old:=X1;`	Explicit query of edge detection without function or function block.
Also possible:	`(* rising edge ) R_TRIG_X0( CLK:= X0 ); IF R_TRIG_X0.Q THEN Count:=Count+1; END_IF; ( falling edge *) F_TRIG_X1( CLK:= X1 ); IF F_TRIG_X1.Q THEN Count:=Count-1; END_IF;`	Using R_TRIG or F_TRIG function block instances from the IEC standard library.
Also possible:	`(* rising edge ) IF DF(X0) THEN Count:=Count+1; END_IF; ( falling edge *) IF DFN(X1) THEN Count:=Count-1; END_IF;`	Using the basic functions DF or DFN.