Power-Programmierung/CD1.mdf/pascal/library/dos/ootp/chap02/list2_3.pas

Pascal/Delphi Source File | 1990-03-08 | 6.6 KB | 262 lines

program Listing2_3;

uses Crt; { for KeyPressed }

const

ON  = true;
OFF = false;
MinR = 0;       { Minimum number of counts in an analog input }
MaxR = 4095;    { Maximum number of counts in an analog input }

var
    f : text;  {predefined file type}


type

Resolution = 0..4095;  { Range for analog input }
String12 = string[12];

Tag = object
      TagNumber : String12;
      procedure Init( ATag : String12 );
      end;

Digital = object(Tag)
          Status : boolean;
          procedure Init( ATag : String12; AStatus : boolean );
          procedure PutStatus( AStatus : boolean );
          function GetStatus : boolean;
          end;

Analog = object(Tag)
         Value : Resolution;
         ZeroVal : real;
         MaxVal : real;
         Slope  : real;
         procedure Init( ATag : String12; AValue : Resolution;
                         Min, Max : real );
         procedure PutValue( AValue : real );
         function GetValue : real;
         end;

DOutput = object(Digital)
          end;

Pump = object(DOutput)
       FlowRate : real;
       procedure Init( ATag : String12; AStatus : boolean; AFlow : real );
       function Flow : real;
       end;


DInput = object(Digital)
            Setpoint  : real;
            Reading   : real;
            procedure PutSetpoint( NewSetpoint : real );
            end;

HiSwitch = object(DInput)
           procedure Init( ATag : string;
                         ASetpoint : real;
                         AReading : real);
           procedure PutReading( NewReading : real );
           end;

LoSwitch = object(DInput)
           procedure Init( ATag : string;
                         ASetpoint : real;
                         AReading : real);
           procedure PutReading( NewReading : real );
           end;

procedure Tag.Init( ATag : String12 );
begin
     TagNumber := ATag;
end;

procedure Digital.Init( ATag : String12; AStatus : boolean );
begin
     Tag.Init( ATag );
     Status := AStatus;
end;
procedure Digital.PutStatus( AStatus : boolean );
begin
     Status := AStatus;
end;
function Digital.GetStatus : boolean;
begin
     if Status = on then
        writeln( f, TagNumber, ' is ON.' )
     else
        writeln( f, TagNumber, ' is OFF.' );
     GetStatus := Status;
end;

procedure Pump.Init( ATag : String12; AStatus : boolean; AFlow : real );
begin
     Digital.Init( ATag, AStatus );
     FlowRate := AFlow;
end;

function Pump.Flow : real;
begin
     Flow := FlowRate;
end;

procedure Analog.Init( ATag : String12;
                       AValue : Resolution;
                       Min, Max : real );
begin
     Tag.Init( ATag );
     Value := AValue;
     MaxVal := Max;
     ZeroVal := Min;
     Slope := (Max-Min)/(MaxR-MinR);
end;

procedure Analog.PutValue( AValue : real );
begin
     if AValue > MaxVal then
        AVAlue := MaxVal
     else
        if AValue < ZeroVal then
           AValue := ZeroVal;
     Value := Round((AValue - ZeroVal)/Slope);
end;

function Analog.GetValue : real;
begin
     GetValue := Slope*Value + ZeroVal;
end;

procedure DInput.PutSetpoint( NewSetpoint : real );
begin
     Setpoint := NewSetpoint;
end;

procedure LoSwitch.Init( ATag : string;
                         ASetpoint : real;
                         AReading : real);
begin
     Tag.Init( ATag );
     DInput.PutSetpoint( ASetpoint );
     PutReading( AReading );
end;

procedure LoSwitch.PutReading( NewReading : real );
begin
     Reading := NewReading;
     if Reading <= Setpoint then
        Status := true
     else
        Status := false;
end;

procedure HiSwitch.Init( ATag : string;
                         ASetpoint : real;
                         AReading : real);
begin
     Tag.Init( ATag );
     DInput.PutSetpoint( ASetpoint );
     PutReading( AReading );
end;

procedure HiSwitch.PutReading( NewReading : real );
begin
     Reading := NewReading;
     if Reading >= Setpoint then
        Status := true
     else
        Status := false;
end;

{ HtToPSI converts a height (of a column of water) into a pressure.
  The math is pretty simple:  A column of water 2.31 feet high exerts
  a force of one pound per square inch at the bottom. }

function HtToPSI( Height : real ) : real;
begin
     HtToPSI := Height/2.31;
end;

{ FlowToDeltaHt converts a flow into (or out of) our system into a
  change in height in the tank.
  The math is as follows:  Divide the flow, in gpm, by 7.48 gal/cu.ft.
  to get the number of cubic feet pumped per minute.  Divide this
  number by the volume of 1 vertical foot of the tank, which is
  the radius squared times 'pi' (15*15*3.1416). }

function FlowToDeltaHt( Flow : real ) : real;
begin
     FlowToDeltaHt := Flow/(7.48 * 706) ;
end;

var
   LT100,
   FT100  : Analog;
   PSL100 : LoSwitch;
   PSH100 : HiSwitch;
   EY100  : Pump;
   time   : integer;

begin

     { If no file name is passed to the program, then ParamStr(1)
       will be the null string, which will cause Assign to output
       to the standard output (the screen).  If a file name is
       passed, the output will be saved in the file for later
       reference. }

     Assign( f, ParamStr(1) );
     Rewrite( f );

     LT100.Init( 'LT100', 512, 50, 250 );
     FT100.Init( 'FT100', 2048, 0, 10000 );
     PSL100.Init( 'PSL100', 60, HtToPSI(LT100.GetValue) );
     PSH100.Init( 'PSH100', 75, HtToPSI(LT100.GetValue) );
     EY100.Init( 'EY100', off, 8000);
     time := 0;

     repeat

     Inc( time );  { increment the time }
     { First, adjust the reading in LT-100 by reducing the level in
       LT100.Value by an amount corresponding to the flow out of the
       system.  We do this by fetching the value of FT100, converting
       it to a height in the tank, and subtracting from the actual
       height... }
     LT100.PutValue( LT100.GetValue - FlowToDeltaHt(FT100.GetValue) );

     { We take the result and update the switches }
     PSL100.PutReading( HtToPSI(LT100.GetValue) );
     PSH100.PutReading( HtToPSI(LT100.GetValue) );

     {Let's publish the level in the tank...}
     writeln( f, 'Level in tank is ', LT100.GetValue:2:2, ' feet at minute ', time );

     { If the pressure is too low, turn on the pump }
     if PSL100.GetStatus = on then
        EY100.PutStatus( ON );
     { If the pressure is too high, turn off the pump }
     if PSH100.GetStatus = on then
        EY100.PutStatus( OFF );

     LT100.PutValue( LT100.GetValue + FlowToDeltaHt( EY100.Flow ));

     until KeyPressed;
     Close ( f );
end.