FUNCTION_BLOCK fb19

VAR_INPUT

FansSelection  : INT;           // HMI Fans Selections

Update_Bt      : BOOL := FALSE; // HMI Update button

FTP_Start      : BOOL;

FTP_Stop       : BOOL;

END_VAR

VAR_OUTPUT

Fan1_start : BOOL;

Fan2_start : BOOL;

Fan3_start : BOOL;

END_VAR

VAR_TEMP

index : INT;

target_fan_to_run : INT;

Update_Button :BOOL ;

END_VAR

CONST

ST_IDLE                   := 0;

ST_WAIT                   := 1;

ST_TURN_ON_TARGET_FAN     := 2;

ST_NORAML_OP_2FANS        := 3;

ST_NORAML_OP_3FANS        := 4;

ST_TURN_OFF_UNWANTED_FAN  := 5;

END_CONST

VAR

Fan_Lookuptable : ARRAY[0..3, 0..2] OF INT :=

    1, 2, 0,

    2, 3, 0,

    3, 1, 0,

    1, 2, 3;

Index_Selection : ARRAY[0..8] OF INT:= -1, 0, 1, -1, 2, -1, -1, -1, 3;


Fan_Run       : ARRAY[0..2] OF BOOL := 0, 0, 0;

old_running   : ARRAY[0..2] OF INT  := 0, 0, 0;

already_started : BOOL;

Update_Button_old : BOOL;

updated : BOOL := FALSE ;

No_TargetFans   : INT;

unused_fan      : INT;

State           : INT;  // FSM current state

TON_timer       : sfb4;

Running_fan     : INT := 0;

END_VAR

BEGIN

IF FansSelection < 1 THEN

    FansSelection := 1;

END_IF;



//index := REAL_TO_INT(LN(FansSelection) / LN(2.0));
index := Index_Selection[FansSelection];

Update_Button:= Update_Bt AND NOT Update_Button_old;

Update_Button_old:=Update_Bt;

CASE State OF



    // ----------------------

    ST_IDLE :

    // ----------------------

        No_TargetFans := 2 + BOOL_TO_INT(FansSelection=8);



        Fan1_start := FALSE;

        Fan2_start := FALSE;

        Fan3_start := FALSE;

        already_started := FALSE;

        updated:= FALSE;

        Running_fan := 0 ;

        // Reset timer

        TON_timer(IN := 0);





        IF FTP_Start THEN

            State := ST_WAIT;

        END_IF;



    // ----------------------

    ST_WAIT :

    // ----------------------

        IF NOT TON_timer.Q THEN

            TON_timer(IN := 1, PT:= T#5s);

        END_IF;



        IF TON_timer.Q THEN

            State := ST_TURN_ON_TARGET_FAN;

        END_IF;



    // ----------------------

    ST_TURN_ON_TARGET_FAN :

    // ----------------------

        IF NOT already_started THEN

            target_fan_to_run := Fan_Lookuptable[index,Running_fan];

        ELSE

            target_fan_to_run := 6 - (old_running[0] + old_running[1]);

        END_IF;



        Fan_Run[target_fan_to_run - 1] := TRUE;

        old_running[Running_fan] := target_fan_to_run;



        Running_fan := Running_fan + 1;



        // Reset timer

        TON_timer(IN := 0);



        IF Running_fan < No_TargetFans THEN

            State := ST_WAIT;

        ELSE

            already_started := TRUE;

            State := ST_NORAML_OP_2FANS + BOOL_TO_INT(Running_fan = 3);

        END_IF;



    // ----------------------

    ST_NORAML_OP_2FANS :

    // ----------------------

        IF  NOT updated THEN

            old_running[0] := Fan_Lookuptable[index,0];

            old_running[1] := Fan_Lookuptable[index,1];

            updated := TRUE;

        END_IF;

        

        IF Update_Button  THEN

            IF FansSelection = 8 THEN

                No_TargetFans := 3;

                State := ST_TURN_ON_TARGET_FAN;

            ELSE

                State := ST_TURN_OFF_UNWANTED_FAN;

            END_IF;

            updated := False;

        END_IF;



     IF FTP_Stop THEN 

        State := ST_IDLE;

     END_IF ;

    // ----------------------

    ST_NORAML_OP_3FANS :

    // ----------------------

        No_TargetFans := 3;



        IF Update_Button AND (FansSelection <> 8) THEN

            No_TargetFans := 2;

            State := ST_TURN_OFF_UNWANTED_FAN;

        END_IF;

        

       IF FTP_Stop THEN 

        State := ST_IDLE;

      END_IF ;



    // ----------------------

    ST_TURN_OFF_UNWANTED_FAN :

    // ----------------------

        unused_fan := 6 - (Fan_Lookuptable[index,0] + Fan_Lookuptable[index,1] + Fan_Lookuptable[index,2]);



        Fan_Run[unused_fan - 1] := FALSE;



        Running_fan := Running_fan - 1;



        IF Running_fan = 2 THEN

            State := ST_NORAML_OP_2FANS;

        ELSE

            State := ST_WAIT;

        END_IF;



END_CASE;

// Update_Button := FALSE ;

Fan1_start := Fan_Run[0];

Fan2_start := Fan_Run[1];

Fan3_start := Fan_Run[2];

END_FUNCTION_BLOCK