Split up serial data in delphi - delphi

Question

I am a newbie in Delphi programming and I need some help. I have a problem with spliting my serial data. This is my code:
procedure TForm1.ComPort1RxChar(Sender: TObject; Count: Integer);
var
DataByte : string;
x, i: integer;
save_data : TStringList;
begin
save_data := TStringList.create;
for x := 0 to Count-1 do begin
ComPort1.ReadStr(DataByte,1);
if DataByte = 'n' then
begin
memo1.Text := '';
end
else
begin
memo1.Text := memo1.Text + DataByte;
Split(' ', DataByte, save_data);
end;
end;
save_gyroX := save_data[0];
save_gyroY := save_data[1];
save_gyroZ := save_data[2];
save_accelX := save_data[3];
save_accelY := save_data[4];
save_accelZ := save_data[5];
SerialProcess();
save_data.Free;
end;
My Split(' ', DataByte, save_data); doesn't work. I don't understand because I just split String data which is taken from the serial port. This is my Split() procedure:
procedure TForm1.Split(const Delimiter: Char; Input: string; const Strings: TStrings) ;
begin
Assert(Assigned(Strings));
Strings.Clear;
Strings.Delimiter := Delimiter;
Strings.DelimitedText := Input;
end;
I do not know why my program is giving me a EStringListError error.

Answer 1

You are calling ReadStr() to read individual bytes, and calling Split() on every byte (except for 'n'). So the TStringList will only ever hold 1 string at a time. Like MBo said, you need to fix your loop to avoid that, eg:
procedure TForm1.ComPort1RxChar(Sender: TObject; Count: Integer);
var
DataByte : string;
x: integer;
save_data : TStringList;
begin
ComPort1.ReadStr(DataByte, Count);
for x := 1 to Length(DataByte) do
begin
if DataByte[x] = 'n' then
begin
Memo1.Text := '';
end
else
begin
Memo1.Text := Memo1.Text + DataByte[x];
end;
end;
save_data := TStringList.create;
try
Split(' ', DataByte, save_data);
save_gyroX := save_data[0];
save_gyroY := save_data[1];
save_gyroZ := save_data[2];
save_accelX := save_data[3];
save_accelY := save_data[4];
save_accelZ := save_data[5];
SerialProcess();
finally
save_data.Free;
end;
end;
That being said, you are not taking into account that the number of bytes you receive for any given OnRxChar event call is arbitrary. It is whatever raw bytes have been read at that exact moment. You are assuming a full string with at least 6 delimited substrings, and that is simply not guaranteed. You need to buffer the raw data as you receive it, and then parse and remove only completed strings from the buffer as needed.
Try something more like this:
var
DataBuffer: string;
// consider using the OnRxBuf event instead...
procedure TForm1.ComPort1RxChar(Sender: TObject; Count: Integer);
var
DataByte : string;
x: integer;
save_data : TStringList;
begin
ComPort1.ReadStr(DataByte, Count);
DataBuffer := DataBuffer + DataByte;
x := Pos('n', DataBuffer);
if x = 0 then Exit;
save_data := TStringList.Create;
try
repeat
DataByte := Copy(DataBuffer, 1, x-1);
Delete(DataBuffer, 1, x);
Memo1.Text := DataByte;
Split(' ', DataByte, save_data);
if save_data.Count >= 6 then
begin
save_gyroX := save_data[0];
save_gyroY := save_data[1];
save_gyroZ := save_data[2];
save_accelX := save_data[3];
save_accelY := save_data[4];
save_accelZ := save_data[5];
SerialProcess();
end;
x := Pos('n', DataBuffer);
until x = 0;
finally
save_data.Free;
end;
end;

Answer 2

if Comport is Dejan Crnila CPort class, then this line
ComPort1.ReadStr(DataByte,1);
replaces Databyte contents every time, and this string always is 1-byte length.
Just read all bytes from buffer with single call
ComPort1.ReadStr(DataByte, Count);
and do work with string