Strange Serial Port Problem

[buggex]

Hey!
I have runned into a strange problem, when trying to setup a serial port. The code I use to open the port:

// Opening the Port "COM1"
hComm = CreateFile( "COM1", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
 
// DCB Settings (Baudrate, parity, numBits, stopBit)
FillMemory(&dcb, sizeof(dcb), 0);
dcb.DCBlength = sizeof(dcb);
BuildCommDCB("57600,n,8,1", &dcb);
 
// Communications time-outs
timeouts.ReadIntervalTimeout = MAXDWORD; 
timeouts.ReadTotalTimeoutMultiplier = 0;
timeouts.ReadTotalTimeoutConstant = 0;
timeouts.WriteTotalTimeoutMultiplier = 0;
timeouts.WriteTotalTimeoutConstant = 0;
SetCommTimeouts(hComm, &timeouts);

When I execute my program i can not read or write data to the port. Then I open the serial port with PUTTY and close PUTTY. Then I execute my prpgram again, and now I can both read and write to the port. Any one that can tell me whats going on???

[weaknessforcats]

Is your file handle hComm valid??

You don't check it after CreateFile.

[buggex]

yes the handle is valid.

[arthurshen]

yes the handle is valid.

Hi!buggex. When I looking your code.I only find that you just opened

your COM1 port ,set up DCB structure and Timeout . I guess that you

you need another function "readfile()" and "writefile()".Then,operate

hComm handle for read or write COM port.

[buggex]

Hi!buggex. When I looking your code.I only find that you just opened

your COM1 port ,set up DCB structure and Timeout . I guess that you

you need another function "readfile()" and "writefile()".Then,operate

hComm handle for read or write COM port.

Yes i have them to.

The write command

WriteFile(hComm, (LPVOID)&lpBuf, 1, &dwWritten, NULL);

The read command

ReadFile(hComm, lpBuf, 1, &dwRead, NULL);

[arthurshen]

Yes i have them to.

The write command

WriteFile(hComm, (LPVOID)&lpBuf, 1, &dwWritten, NULL);

The read command

ReadFile(hComm, lpBuf, 1, &dwRead, NULL);

Dear:BUGGEX

I have no ideal that your problem was already solved or not.Basically,I thought on the matter was two strange points.

First,you excused your program and it had not error?? It's just not work for I/O.

Second ,you excused your program after used PUTTY.But your program It's work??

About your first strange point,As result of your codes information are not complete enough.So I can't help you.

As for second ,I got some information from MSDN document below this URL
http://msdn2.microsoft.com/en-us/library/aa363423(VS.85).aspx

Maybe,the first paragraph is what you wanna know.