转载：http://www.cnblogs.com/Bung/archive/2011/05/20/2051636.html
通过comport获取计算机中的所有串口号：
procedure TForm1.FormCreate(Sender: TObject); //获取计算机中的串口号
var
Cnumber:TStrings;
i:Integer;
begin
cbb2.Items.Clear;
Cnumber:=TStringList.Create;
EnumComPorts(Cnumber); //获取串口号函数：EnumComPorts
for i:=0 to Cnumber.Count-1 do
begin
cbb2.Items.Add(Cnumber.Strings[i])
end;
cbb2.ItemIndex:=0;
Cnumber.Free;
end;
procedure TForm1.btn7Click(Sender: TObject); //打开串口
begin
ComPort1.Port:=cbb2.Text;
if ComPort1.Connected then
begin
ComPort1.Close;
ComPort1.Open;
end
else
ComPort1.Open;
end;
我开始用comport时发现它每次14个字符触发一次接收事件，而我要接收的一帧完整数据是82个字符，因此我在每帧的前后个加了开始码和结束码，共84个字符，当Count值大于84我才处理，程序片断如下：
procedure TFCOMM.ComPortRxChar(Sender: TObject; Count: Integer);
var
ReceiveData:TDateRec;
p:Pbyte;
Block : array[0..85] of Char;
begin
if (not Ready) then
begin
ComPort.Read(p,1); //开始码为$7FFE,接收时先收的是$FE
move(p, SecondByte,1);
if SecondByte = $FE then //如果收到的字节是$FE，那就看看下一个是不是$7F
begin
FirstByte := SecondByte;
ComPort.Read(p,1);;
move(p, SecondByte,1);
end;
end;
if (FirstByte = $FE) and (SecondByte = $7F) then
Ready := True;
if Ready and (count>=84) then
begin
。。。。
end;
end;
Spcomm有的是定时查询的方式读COM口；而ComPort用Overlapped机制进行COM读写，只要COM有数据接收到，ComPort就能够从Event响应，并通知应用程序接收，所以，某种ComPort的实时性更好。但是，Overlapped的Event被触发，并不是COM接入一段完整的信息才触发，是Windows自己决定的，我在多个计算机和不同的Windows版本上试过，其触发后接收到的字符数并不一样。因此，需要自己建一个缓冲区来处理数据。
procedure TCustomComPort.CreateHandle;
begin
FHandle := CreateFile(
PChar('\\.\' + FPort),
GENERIC_READ or GENERIC_WRITE,
0,
nil,
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED, // 以Overlapped方式打开COM口
0);
if FHandle = INVALID_HANDLE_VALUE then
raise EComPort.Create(CError_OpenFailed, GetLastError);
end;
procedure TComThread.Execute;
var
EventHandles: array[0..1] of THandle;
Overlapped: TOverlapped;
Signaled, BytesTrans, Mask: DWORD;
begin
FillChar(Overlapped, SizeOf(Overlapped), 0);
Overlapped.hEvent := CreateEvent(nil, True, True, nil);
EventHandles[0] := FStopEvent;
EventHandles[1] := Overlapped.hEvent; // COM口上的Overlapped事件
repeat
// 等待COM上的事件
// wait for event to occur on serial port
WaitCommEvent(FComPort.Handle, Mask, @Overlapped);
Signaled := WaitForMultipleObjects(2, @EventHandles, False, INFINITE);
// if event occurs, dispatch it
if (Signaled = WAIT_OBJECT_0 + 1)
and GetOverlappedResult(FComPort.Handle, Overlapped, BytesTrans, False)
then
begin
// 通知应用程序接收数据
FEvents := IntToEvents(Mask);
DispatchComMsg;
end;
until Signaled <> (WAIT_OBJECT_0 + 1);
// clear buffers
SetCommMask(FComPort.Handle, 0);
PurgeComm(FComPort.Handle, PURGE_TXCLEAR or PURGE_RXCLEAR);
CloseHandle(Overlapped.hEvent);
CloseHandle(FStopEvent);
end;
Cport - 应用集合
通过comport获取计算机中的所有串口号：
procedure TForm1.FormCreate(Sender: TObject); //获取计算机中的串口号
var
Cnumber:TStrings;
i:Integer;
begin
cbb2.Items.Clear;
Cnumber:=TStringList.Create;
EnumComPorts(Cnumber); //获取串口号函数：EnumComPorts
for i:=0 to Cnumber.Count-1 do
begin
cbb2.Items.Add(Cnumber.Strings[i])
end;
cbb2.ItemIndex:=0;
Cnumber.Free;
end;
procedure TForm1.btn7Click(Sender: TObject); //打开串口
begin
ComPort1.Port:=cbb2.Text;
if ComPort1.Connected then
begin
ComPort1.Close;
ComPort1.Open;
end
else
ComPort1.Open;
end;
我开始用comport时发现它每次14个字符触发一次接收事件，而我要接收的一帧完整数据是82个字符，因此我在每帧的前后个加了开始码和结束码，共84个字符，当Count值大于84我才处理，程序片断如下：
procedure TFCOMM.ComPortRxChar(Sender: TObject; Count: Integer);
var
ReceiveData:TDateRec;
p:Pbyte;
Block : array[0..85] of Char;
begin
if (not Ready) then
begin
ComPort.Read(p,1); //开始码为$7FFE,接收时先收的是$FE
move(p, SecondByte,1);
if SecondByte = $FE then //如果收到的字节是$FE，那就看看下一个是不是$7F
begin
FirstByte := SecondByte;
ComPort.Read(p,1);;
move(p, SecondByte,1);
end;
end;
if (FirstByte = $FE) and (SecondByte = $7F) then
Ready := True;
if Ready and (count>=84) then
begin
。。。。
end;
end;
Spcomm有的是定时查询的方式读COM口；而ComPort用Overlapped机制进行COM读写，只要COM有数据接收到，ComPort就能够从Event响应，并通知应用程序接收，所以，某种ComPort的实时性更好。但是，Overlapped的Event被触发，并不是COM接入一段完整的信息才触发，是Windows自己决定的，我在多个计算机和不同的Windows版本上试过，其触发后接收到的字符数并不一样。因此，需要自己建一个缓冲区来处理数据。
procedure TCustomComPort.CreateHandle;
begin
FHandle := CreateFile(
PChar('\\.\' + FPort),
GENERIC_READ or GENERIC_WRITE,
0,
nil,
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED, // 以Overlapped方式打开COM口
0);
if FHandle = INVALID_HANDLE_VALUE then
raise EComPort.Create(CError_OpenFailed, GetLastError);
end;
procedure TComThread.Execute;
var
EventHandles: array[0..1] of THandle;
Overlapped: TOverlapped;
Signaled, BytesTrans, Mask: DWORD;
begin
FillChar(Overlapped, SizeOf(Overlapped), 0);
Overlapped.hEvent := CreateEvent(nil, True, True, nil);
EventHandles[0] := FStopEvent;
EventHandles[1] := Overlapped.hEvent; // COM口上的Overlapped事件
repeat
// 等待COM上的事件
// wait for event to occur on serial port
WaitCommEvent(FComPort.Handle, Mask, @Overlapped);
Signaled := WaitForMultipleObjects(2, @EventHandles, False, INFINITE);
// if event occurs, dispatch it
if (Signaled = WAIT_OBJECT_0 + 1)
and GetOverlappedResult(FComPort.Handle, Overlapped, BytesTrans, False)
then
begin
// 通知应用程序接收数据
FEvents := IntToEvents(Mask);
DispatchComMsg;
end;
until Signaled <> (WAIT_OBJECT_0 + 1);
// clear buffers
SetCommMask(FComPort.Handle, 0);
PurgeComm(FComPort.Handle, PURGE_TXCLEAR or PURGE_RXCLEAR);
CloseHandle(Overlapped.hEvent);
CloseHandle(FStopEvent);
end;