Threading with CPort - multithreading

Question

I'm trying to write a simple CPort application in delphi.
I want it to listen to a port, upon receiving a message, it will wait 4 seconds then send a string in response.
unit Tests.Mocks.Refractometer;
interface
uses
CPort,
Classes
;
type
TRefractometerMock = class
strict private
MockRunThread : TThread;
ComPort : TComPort;
ComDataPacket: TComDataPacket;
public
procedure Open;
procedure HandlePacket(Sender : TObject; const Str : String);
constructor Create; overload;
constructor Create(BaudRate : TBaudRate; Port : String); overload;
destructor Destroy; override;
end;
implementation
uses
SysUtils,
StrUtils
;
procedure TRefractometerMock.HandlePacket(Sender : TObject; const Str : String);
begin
MockRunThread.Start;
end;
procedure TRefractometerMock.Open;
begin
ComPort.Open;
end;
constructor TRefractometerMock.Create(BaudRate : TBaudRate; Port : String);
begin
Self.Create;
Self.ComPort.Port := Port;
Self.ComPort.BaudRate := BaudRate;
end;
constructor TRefractometerMock.Create;
begin
inherited;
ComPort := TComPort.Create(nil);
ComDataPacket := TComDataPacket.Create(nil);
ComDataPacket.ComPort := ComPort;
ComDataPacket.OnPacket := HandlePacket;
MockRunThread := TThread.CreateAnonymousThread
(
procedure
begin
Sleep(4000);
Self.ComPort.WriteStr('nD=1.33308;');
end
);
end;
destructor TRefractometerMock.Destroy;
begin
if Assigned(Self.ComPort) then FreeAndNil(Self.ComPort);
if Assigned(ComDataPacket) then FreeAndNil(ComDataPacket);
if Assigned(MockRunThread) then FreeAndNil(MockRunThread);
inherited;
end;
end.
using this unit I can use the following code to
Start listening
RefractometerMock := TRefractometerMock.Create(TBaudRate.br9600, 'COM7');
try
RefractometerMock.Open;
Sleep(8000);
finally
FreeAndNil(RefractometerMock);
end;
Also note that I'm using com0com to create a bridge between ports COM6 and COM7.
I'm sending a putty message on port COM6
The problem is that even though I have sent a message with putty, the HandlePacket method does not get called until the TRefractometerMock object is freed.
First
Then
Then
Finally
I'm not even sure how this is possible since I thought this object had been destroyed.

Answer 1

You are blocking the main thread by Sleep(8000). This means that the com port driver is not able to call the HandlePacket method.
When the sleep is over, it is too late to handle anything, since everything is freed.
Since you are handling the life time of the anonymous thread, you should set the FreeOnTerminate property to false. And free the com port after the anonymous thread.
Use a timer instead of the Sleep() call.

Answer 2

I don't see any settings for ComDataPacket. From help: Packet ends when one of stop conditions occurs. Did you define these stop conditions?
Have you checked data receiving using ComDataPacket in simple standalone application, without intermediate class?
BTW, it seems that TTimer could do the work, thread is not necessary here.

Answer 3

Since Brian Frost wants the code here it is, this is too big to fit in a comment.
Create a simple form
type
TFrmMockRefrac = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
{ Private declarations }
public
RefractometerMock : TRefractometerMock;
{ Public declarations }
end;
var
FrmMockRefrac: TFrmMockRefrac;
Handle creating and destruction without the Sleep function
procedure TFrmMockRefrac.FormCreate(Sender: TObject);
begin
RefractometerMock := TRefractometerMock.Create(TBaudRate.br9600, 'COM7');
RefractometerMock.Open;
end;
procedure TFrmMockRefrac.FormDestroy(Sender: TObject);
begin
FreeAndNil(RefractometerMock);
end;