Delphi TCPClient Issue - delphi

Question

I am new to Delphi and trying to convert vb.net apps to learn. The issue I am having is reading from a TCP/IP host. Currently I can connect via telnet to the device, send a command, and the device will send data non-stop until all data is sent. This could be simply two characters followed by CR/LF, or it could be several rows of varing length data. Each row is end is CR/LF. Prior to writing code, we were able to telnet via Hyperterminal to the device. Send a command, and, with the capture text enabled save to a text file.
Below is the code I have so far. I have not coded for saving to text file (one step at a time). The data is pipe delimited. I have no control on the format or operatation of the device aside from sending commands and receiving data. It works most of the time however there are times when not all of the data (65 records for testing) are received. I will greatly appreciate guidence and feel free to comment on my code, good or bad.
function Parse(Char, S: string; Count: Integer): string;
var
I: Integer;
T: string;
begin
if S[Length(S)] <> Char then
S := S + Char;
for I := 1 to Count do
begin
T := Copy(S, 0, Pos(Char, S) - 1);
S := Copy(S, Pos(Char, S) + 1, Length(S));
end;
Result := T;
end;
procedure TForm2.btnEXITClick(Sender: TObject);
begin
if idTcpClient1.connected then
begin
idTcpClient1.IOHandler.InputBuffer.clear;
idTcpClient1.Disconnect;
end;
Close;
end;
procedure TForm2.btnSendDataClick(Sender: TObject);
var
mTXDataString : String;
RXString : String;
begin
IdTCPClient1.Host := IPAddress.Text;
IdTCPClient1.Port := StrToInt(IPPort.Text);
mTXDataString := mTXData.Text + #13#10;
IdTCPClient1.Connect;
If IdTCPClient1.Connected then
begin
IdTCPClient1.IOHandler.Write(mTXDataString);
mTXDataString := mTXData.Lines.Text;
if MTXDataString.Contains('SCHEMA') then
begin
mRXData.Lines.Add(IdTCPClient1.IOHandler.ReadLn);
while not (IdTCPClient1.IOHandler.InputBufferIsEmpty) do
begin
RXString := IdTCPClient1.IOHandler.ReadLn;
If (RXString <> '') and (RXString <> '??') then
begin
//Add received data to RXmemo
mRXData.Lines.Add(RXString);
//Determine number of records to received based on schema data
lblRecords.Caption := Parse(',', RXString, 2);
end;
end; //while not
end // if
else
if mTXDataString.Contains('DATA') then
begin
mRXData.Lines.Add(IdTCPClient1.IOHandler.ReadLn);
while not (IdTCPClient1.IOHandler.InputBufferIsEmpty) do
begin
RXString := IdTCPClient1.IOHandler.ReadLn;
If (RXString <> '') and (RXString <> '??') then
begin
mRXData.Lines.Add(RXString);
end; // if
end; //while not
end; // if Schema or not
end; // if Connected
IdTCPClient1.Disconnect;
end; //Procedure

Answer 1

HyperTerminal and Telnet apps display whatever data they receive, in real-time. TIdTCPClient is not a real-time component. You control when and how it reads. If you are expecting data to arrive asynchronously, especially if you don't know how many rows are going to be received, then you need to perform the reading in a timer or worker thread, eg:
procedure TForm2.TimerElapsed(Sender: TObject);
var
S: String;
begin
if IdTCPClient1.IOHandler = nil then Exit;
if IdTCPClient1.IOHandler.InputBufferIsEmpty then
begin
IdTCPClient1.IOHandler.CheckForDataOnSource(50);
if IdTCPClient1.IOHandler.InputBufferIsEmpty then Exit;
end;
S := IdTCPClient1.IOHandler.ReadLn;
// use S as needed ...
end;
Or:
type
TMyThread = class(TThread)
protected
fClient: TIdTCPClient;
procedure Execute; override;
public
constructor Create(aClient: TIdTCPClient);
end;
constructor TMyThread.Create(aClient: TIdTCPClient);
begin
inherited Create(False);
fClient := aClient;
end;
procedure TMyThread.Execute;
var
S: String;
begin
while not Terminated do
begin
S := fClient.IOHandler.ReadLn;
// use S as needed ...
end;
end;
Or, if the server supports the actual Telnet protocol, have a look at using Indy's TIdTelnet component instead.