Comparison of programming editors

Possible criteria for selecting a programming editor may be to:

reduce the number of programming steps required
provide a better overview by saving space in the programming window
to save time when restructuring the program

Boolean operations: LD/FBD editor recommended

LD/FBD (recommended)	ST	IL
	`(* 2 of 3 ) Y1:=NOT X1 AND X2 AND X3 OR X1 AND NOT X2 AND X3 OR X1 AND X2 AND NOT X3; ( Handle error case ) if (Error1 OR Error2 OR Error3) then Alarm:=TRUE; Horn :=TRUE; end_if; ( Confirm alarm ) if (ConfirmAlarm) then Horn:=FALSE; end_if; ( Reset alarm *) if (ResetAlarm AND NOT Error1 AND NOT Error2 AND NOT Error3) then Alarm:=FALSE; Horn :=FALSE; end_if;`
42 steps	35 steps	35 steps

LD/FBD (recommended)

(* 2 of 3 *)
Y1:=NOT X1 AND X2 AND X3 OR
    X1 AND NOT X2 AND X3 OR
    X1 AND X2 AND NOT X3;

(* Handle error case *)
if (Error1 OR Error2 OR Error3) then
    Alarm:=TRUE;
    Horn :=TRUE;
end_if;

(* Confirm alarm *)
if (ConfirmAlarm) then
    Horn:=FALSE;
end_if;

(* Reset alarm *)
if (ResetAlarm AND NOT Error1 AND NOT Error2 AND
NOT Error3) then
    Alarm:=FALSE;
    Horn :=FALSE;
end_if;

42 steps

35 steps

Function calls: LD/FBD editor recommended

LD/FBD (recommended)	ST	IL
	`(* Calculate statistical parameters *) if (bCalculateStatistics) then StatisticalCalculations(CalculateSum := bCalcSum, CalculateMean := bCalcMean, CalculateDeviation := bCalcDeviation, Number := 3, Input1 := Integer1, Input2 := Integer2, Input3 := Integer3, Sum => Sum, Mean => Mean, Deviation => Deviation); end_if;`
32 steps	35 steps	35 steps

LD/FBD (recommended)

(* Calculate statistical parameters *)
if (bCalculateStatistics) then
   	StatisticalCalculations(CalculateSum := bCalcSum,
                            CalculateMean := bCalcMean,
                            CalculateDeviation := bCalcDeviation,
                            Number := 3,
                            Input1 := Integer1,
                            Input2 := Integer2,
                            Input3 := Integer3,
                            Sum => Sum,
                            Mean => Mean,
                            Deviation => Deviation);
end_if;

32 steps

35 steps

Unconditional calculations: ST editor recommended

LD/FBD	ST (recommended)	IL
	`(* Linear interpolation: ) y:=y1+(x-x1)(y2-y1)/(x2-x1);`
108 steps	108 steps	108 steps

Conditional calculations: ST editor recommended

LD/FBD	ST (recommended)	IL
	`(* Conditional linear interpolation ) if (NOT(XLtX1) AND NOT(XGtX2) AND NOT(X1EqualX2)) then y:=y1+(x-x1)(y2-y1)/(x2-x1); end_if;`
111 steps	109 steps	109 steps

Conditional if-else calculations: ST editor recommended

LD/FBD	ST (recommended)	IL
NOTE When changing from unconditional to conditional operation the whole network has to be redrawn!	`if (x > x1) then y:=y1; elsif (x < x2) then y:=y2; elsif (x1 = x2) then y:=(y1 + y2)/2; else (* Linear interpolation ) y:=y1+(x - x1)(y2 - y1)/(x2 - x1); end_if;`
194 steps	190 steps	194 steps

Loop operations: ST editor recommended

LD/FBD	ST (recommendation)	IL
	`Sum:=0; for i := 1 to 10 do Sum:=Sum+Array1[i]; end_for; Mean:=Sum/10;`

Conclusion:

Programs with simple or Boolean calculations and calls of functions or function blocks: LD/FBD editor recommended
Functions and function blocks, also for complex algorithms: ST editor recommended