FP_ATAN2

Convert coordinate data into radians

This FP instruction returns the angle j of the Cartesian coordinates (x,y) within the range of -p to +p.

Parameters

Input

s1_y (ANY_REAL): Cartesian y coordinate
s2_x (ANY_REAL): Cartesian x coordinate

Output

d (REAL): Result in radians

Remarks

Each position P of the two-dimensional coordinates can be defined by Cartesian coordinates P(x,y) or by polar coordinates P(r,j) (r = radius, j = angle).

Define FP_ATAN2 as follows:

ATAN2_YX(y,x)	x	y
	x > 0
	x < 0	y ³ 0
	x < 0	y < 0
	x = 0	y > 0
		y < 0
Operation error		y = 0

Error flags

sys_bIsOperationErrorHold (turns to TRUE and remains TRUE)

if the area specified using the index modifier exceeds the limit.
if a non-real number is specified for s1_y (y coordinate) or s2_x (x coordinate)
if 0.0 is specified for s1_y (y coordinate) and 0.0 for s2_x (x coordinate)

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		bStart: BOOL:=FALSE;
			(*activates the instruction*)
		rPhi1Rad: REAL:=0.0;
		rPhi1Degree: REAL:=0.0;
	END_VAR
	VAR CONSTANT
		DEGR_OF_RAD: REAL:=57.295779513082320876798154814105;
	END_VAR
	VAR
	END_VAR

LD body

When the variable bStart is set to TRUE, the function is carried out.

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 6 ;
        NETWORK_BODY
B(B_F,FP_ATAN2!,,10,1,16,6,,?DEN?Ds1_y?Ds2_x?AENO?Cd);
B(B_VARIN,,10.0,8,3,10,5,);
B(B_VARIN,,-10.0,8,4,10,6,);
B(B_VAROUT,,rPhi1Rad,16,3,18,5,);
B(B_CONTACT,,bStart,3,2,5,4,);
L(1,3,3,3);
L(5,3,10,3);
L(1,0,1,6);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 5 ;
        NETWORK_BODY
B(B_F,@MUL-2!,,11,1,16,4,,?D?D?C);
B(B_VARIN,,rPhi1Rad,9,1,11,3,);
B(B_VARIN,,DEGR_OF_RAD,9,2,11,4,);
B(B_VAROUT,,rPhi1Degree,16,1,18,3,);
L(1,0,1,5);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

rPhi1Rad:=ATAN2_YX(y := 10.0, x := -10.0); (* Result: 2.3561947 *)
rPhi1Degree := rPhi1Rad * DEGR_OF_RAD;     (* Result: 135.00002 *)