如何在Delphi中将十六进制字符串转为TComPort可用的十六进制数据？

Got it, let's solve this. Your goal is to take a space-separated hex string like "D5 D5" and convert it into the same byte sequence as the hardcoded #$D5#$D5 that works with WriteStr. Here's how to do it step by step:

Step-by-Step Explanation #

1. Split the Input String: Break down the space-separated hex pairs into individual segments (e.g., "D5 D5" becomes ["D5", "D5"]).
2. Convert Each Hex Segment to a Byte: Turn each 2-character hex string into its corresponding byte value (e.g., "D5" becomes $D5 or 213 in decimal).
3. Build a Byte-Encoded String: Construct a string where each character represents the byte value (this matches what #$XX does natively).
4. Send the String via TComPort: Pass the built string to WriteStr to send the raw bytes.

Working Delphi Code #

Here's a complete implementation using TStringList to handle splitting the input cleanly, plus error checking for invalid hex values:

procedure TForm1.Button3Click(Sender: TObject);
var
  HexSegments: TStringList;
  I: Integer;
  HexPart: string;
  ByteValue: Integer;
  OutputBytes: AnsiString;
begin
  HexSegments := TStringList.Create;
  try
    // Configure string list to split on spaces
    HexSegments.Delimiter := ' ';
    HexSegments.StrictDelimiter := True;
    HexSegments.DelimitedText := Trim(Edit1.Text);

    OutputBytes := '';

    for I := 0 to HexSegments.Count - 1 do
    begin
      HexPart := Trim(HexSegments[I]);

      // Validate hex segment length
      if Length(HexPart) <> 2 then
      begin
        ShowMessage(Format('Invalid hex segment: "%s" (must be 2 characters)', [HexPart]));
        Exit;
      end;

      try
        // Convert hex string to integer (byte value)
        ByteValue := StrToInt('$' + HexPart);
        // Append the byte as an AnsiChar to our output string
        OutputBytes := OutputBytes + AnsiChar(ByteValue);
      except
        on E: EConvertError do
        begin
          ShowMessage(Format('Failed to convert hex segment "%s": %s', [HexPart, E.Message]));
          Exit;
        end;
      end;
    end;

    // Send the raw byte sequence via TComPort
    ComPort1.WriteStr(OutputBytes);
  finally
    HexSegments.Free;
  end;
end;

Key Notes #

• Unicode Compatibility: Using AnsiString and AnsiChar ensures that each character is treated as a single byte, which is critical in newer Delphi versions (2009+) where string defaults to UTF-16 (2 bytes per character). This matches the behavior of the hardcoded #$D5 literals.
• Error Handling: The code checks for invalid segment lengths and conversion errors, so you'll get clear feedback if the input isn't formatted correctly.
• Input Flexibility: This works with any number of space-separated hex pairs (e.g., "01 02 03" will send three bytes: $01, $02, $03).

内容的提问来源于stack exchange，提问作者Martin Ocando Corleone