How to increase the number of sequential data assigned to a variable?

Question

I downloaded and installed the comport library. I have a simulator sending data through a serial RS232 to a Selphi program. This is the next piece of code.

procedure TMainForm.ComPortRxChar(Sender: TObject; Count: Integer);
begin
  ComPort.ReadStr(CPort.Str, Count);
  Memo.Text := Memo.Text + CPort.Str;
end; 

As for the part of the CPort library, I added:

var
  Str: String;

here is the problem.

The example data that passes is roughly similar to

$HEHDT,288.45,T*1D
$HEHDT,288.46,T*18
$HEHDT,288.47,T*1A

etc. Each line is sent per second. Thus, using the above code, all this data will be displayed in a note.

However, if I changed the code to:

procedure TMainForm.ComPortRxChar(Sender: TObject; Count: Integer);
begin
  ComPort.ReadStr(CPort.Str, Count);
  Memo.Text := Memo.Text + CPort.Str + 'haha';
end;

This is what appears in the note:

$HEHDT,2haha88.45,T*haha1Dhaha
$HEHDT,2haha88.46,T*haha18haha
$HEHDT,2haha88.47,T*haha1Ahaha

Haha appears after 8 ASCII characters. so this means in the CPort.pas library, in the asynchronous / synchronous part, only 8ASCII characters max is assigned to the variable Str?

, , , Str 8 .

** , CPort . - , ? , . !

// split buffer in packets
procedure TComDataPacket.HandleBuffer;

procedure DiscardPacketToPos(Pos: Integer);
var
Str: string;
begin
FInPacket := True;
if Pos > 1 then
begin
  Str := Copy(Buffer, 1, Pos - 1); // some discarded data
  Buffer := Copy(Buffer, Pos, Length(Buffer) - Pos + 1);
  DoDiscard(Str);
end;
end;

procedure FormPacket(CutSize: Integer);
var
Str: string;
begin
Str := Copy(Buffer, 1, CutSize);
Buffer := Copy(Buffer, CutSize + 1, Length(Buffer) - CutSize);
CheckIncludeStrings(Str);
DoPacket(Str);
end;

procedure StartPacket;
var
Found: Integer;
begin
// check for custom start condition
Found := -1;
DoCustomStart(Buffer, Found);
if Found > 0 then
  DiscardPacketToPos(Found);
if Found = -1 then
begin
  if Length(FStartString) > 0 then // start string valid
  begin
    Found := Pos(Upper(FStartString), Upper(Buffer));
    if Found > 0 then
      DiscardPacketToPos(Found);
  end
  else
    FInPacket := True;
end;
end;

procedure EndPacket;
var
Found, CutSize, Len: Integer;
begin
// check for custom stop condition
Found := -1;
DoCustomStop(Buffer, Found);
if Found > 0 then
begin
  // custom stop condition detected
  CutSize := Found;
  FInPacket := False;
end
else
  if Found = -1 then
  begin
    Len := Length(Buffer);
    if (FSize > 0) and (Len >= FSize) then
    begin
      // size stop condition detected
      FInPacket := False;
      CutSize := FSize;
    end
    else
    begin
      Len := Length(FStartString);
      Found := Pos(Upper(FStopString),
        Upper(Copy(Buffer, Len + 1, Length(Buffer) - Len)));
      if Found > 0 then
      begin
        // stop string stop condition detected
        CutSize := Found + Length(FStopString) + Len - 1;
        FInPacket := False;
      end;
    end;
  end;
if not FInPacket then
  FormPacket(CutSize); // create packet
end;

Answer 1

A :

:

(, CRLF, . NMEA 0183)

var
  finalBuf: AnsiString;

// Example packet: $HEHDT,10.17,T*28 + CRLF
// This is a NMEA 0183 protocol (Marine and GPS standard)
// Subset for reading the heading.
// HDT Heading – True
//       1   2 3
//       |   | |
//$--HDT,x.x,T*hh
//1) Heading Degrees, true
//2) T = True
//3) Checksum
// HE stands for: Heading – North Seeking Gyro

{- Checking packet and checksum, calculating heading }
Function ParseAndCheckNMEA_HDT(const parseS: AnsiString;
  var heading: Double): Integer;
// Example packet: $HEHDT,10.17,T*28 + CRLF
var
  i, p, err: Integer;
  xorSum: Byte;
  xorStr: AnsiString;
  headingStr: AnsiString;
begin
  Result := 0; // Assume ok
  if (Pos('$HEHDT', parseS) = 1) then // Start header ok ?
  begin
    p := Pos('*', parseS);
    if (p <> 0) and (Length(parseS) >= p + 2) then
    // Assumes a checksum in packet
    begin
      xorSum := Ord(parseS[2]);
      for i := 3 to p - 1 do // Calculate checksum
        xorSum := xorSum xor Ord(parseS[i]);
      xorStr := IntToHex(xorSum, 2);
      if (UpperCase(xorStr) = Copy(parseS, p + 1, 2)) then // Checksum ok ?
      begin
        // Validate heading
        headingStr := Copy(parseS, 8, p - 10);
        Val(headingStr, heading, err);
        if (err <> 0) then
          Result := 4; // Not a valid float
      end
      else
        Result := 3; // Wrong checksum
    end
    else
      Result := 2; // No checksum
  end
  else
    Result := 1; // Wrong header
end;


procedure TMainForm.ComPortRxChar(Sender: TObject; Count: Integer);
var
  i,err: Integer;
  strBuf: AnsiString;
  heading: Double;
begin
  ComPort.ReadStr(CPort.Str, Count);
  strBuf := CPort.str;
  for i := 1 to Length(strBuf) do
    case strBuf[i] of
      '$' : 
        finalBuf := '$';  // Start of package
      #10 :
        begin
          if (finalBuf <> '') and (finalBuf[1] = '$') then  // Simple validate check 
            begin
              SetLength( finalBuf, Length(finalBuf) - 1); // Strips CR
              err := ParseAndCheckNMEA_HDT(finalBuf, heading);
              if (err = 0) then 
                Memo.Lines.Add(finalBuf); // Add validated string
              //else
              //  Memo.Lines.Add('Error:' + IntToStr(err)); 
            end;
          finalBuf := '';
        end; 
    else
      finalBuf := finalBuf + strBuf[i];  
    end;
end;

, . # 13 # 10 (CR LF), , , . .

2

, "haha" :

comport , , . , . , , . TComPort .

, NMEA 0183. ( , $).

ParseAndCheckNMEA_HDT :

Function ParseAndCheckNMEA(const parseS: AnsiString): Integer;
// Example packet: $HEHDT,10.17,T*28 + CRLF
var
  i, p: Integer;
  xorSum: Byte;
  xorStr: AnsiString;
begin
  Result := 0; // Assume ok
  if (Pos('$', parseS) = 1) then // Start header ok ?
  begin
    p := Pos('*', parseS);
    if (p <> 0) and (Length(parseS) >= p + 2) then
    // Assumes a checksum in packet
    begin
      xorSum := Ord(parseS[2]);
      for i := 3 to p - 1 do // Calculate checksum
        xorSum := xorSum xor Ord(parseS[i]);
      xorStr := IntToHex(xorSum, 2);
      if (UpperCase(xorStr) <> Copy(parseS, p + 1, 2)) then // Checksum ok ?
        Result := 3; // Wrong checksum
    end
    else
      Result := 2; // No checksum
  end
  else
    Result := 1; // Wrong header
end;

Answer 2

. , . , (# 13), :

var Buf: string;

procedure DoSomething(const Str: String);
begin
  Memo.Text := Memo.Text + Str;
end;

procedure TMainForm.ComPortRxChar(Sender: TObject; Count: Integer);
var I: Integer;
begin
  ComPort.ReadStr(CPort.Str, Count);
  Buf := Buf + CPort.Str;        
  for i := 1 to Length(Buf) do
    if Buf[i] = #13 then
    begin
      DoSomething(Copy(Buf, 1, i)); 
      Delete(Buf, 1, i+1);
      Break;
    end;
end;

Answer 3

ComPort Dejan Crnila, TComDataPacket, OnPacket OnCustomStop.

Update: . , , ', T *', (, CRC). , .

procedure TForm136.ComDataPacketCustomStop(Sender: TObject; const Str: string;
    var Pos: Integer);
begin
  Pos := System.Pos(',T*', Str);
  if (Pos > 0) then begin
    Inc(Pos, 4);
    if Pos <= Length(Str) then Exit;
  end;
  Pos := -1;
end;

procedure TForm136.FormCreate(Sender: TObject);
begin
  ComDataPacket.ComPort := ComPort;
  ComDataPacket.StartString := '$HEHDT,';
  ComDataPacket.OnCustomStop := ComDataPacketCustomStop;
end;