Hi,
I've posted earlier a question regarding the call to GetCommState.
Here is the code for the function.
The problem is that GetCommState always returns false!!
Why?
void Open()
{
// the DCB and COMMTIMEOUTS structure are declare a __value struct
DCB *dcbCommPort = __nogc new DCB();
COMMTIMEOUTS *ctoCommPort = __nogc new COMMTIMEOUTS();
// OPEN THE COMM PORT.
hComm = CreateFile("LPT1",GENERIC_READ | GENERIC_WRITE,0, 0,OPEN_EXISTING,0,0);
// IF THE PORT CANNOT BE OPENED, BAIL OUT.
if(hComm == INVALID_HANDLE_VALUE)
{
throw(new ApplicationException("Comm Port Can Not Be Opened"));
}
// SET THE COMM TIMEOUTS.
GetCommTimeouts(hComm,ctoCommPort);
ctoCommPort->ReadTotalTimeoutConstant = ReadTimeout;
ctoCommPort->ReadTotalTimeoutMultiplier = 0;
ctoCommPort->WriteTotalTimeoutMultiplier = 0;
ctoCommPort->WriteTotalTimeoutConstant = 0;
SetCommTimeouts(hComm,ctoCommPort);
// SET BAUD RATE, PARITY, WORD SIZE, AND STOP BITS.
GetCommState(hComm, dcbCommPort);
dcbCommPort->BaudRate=BaudRate;
dcbCommPort->flags=0;
//dcb.fBinary=1;
dcbCommPort->flags|=1;
if (Parity>0)
{
dcbCommPort->flags|=2;
}
dcbCommPort->Parity=Parity;
dcbCommPort->ByteSize=ByteSize;
dcbCommPort->StopBits=StopBits;
if (!SetCommState(hComm, dcbCommPort)) // always returns false
{
throw(new ApplicationException("Comm Port Can Not Be Opened"));
}
Opened = true;
}
Thanks! 5 5825
"CeZaR" <pa****@go.ro> wrote in message
news:fc**************************@posting.google.c om... I've posted earlier a question regarding the call to GetCommState. Here is the code for the function. The problem is that GetCommState always returns false!!
You shouldn't have to guess. _Immediately_ after the function returns, call
GetLastError().
Now, I haven't researched it, but if IJW is trampling on the thread's last
Win32 error by making some intervening Win32 API call, take a look at this: http://blogs.msdn.com/adam_nathan/ar.../25/56643.aspx
Just by the way, is the LPT port in question controlled by a printer driver?
Regards,
Will
I've stopped the spooler service before running the program.
Then i call CreateFile with "\\\\.\\NONSPOOLED_LPT1".
BTW GetLastError returns 2 -> Invalid function.
"William DePalo [MVP VC++]" <wi***********@mvps.org> wrote in message news:<OG**************@TK2MSFTNGP12.phx.gbl>... "CeZaR" <pa****@go.ro> wrote in message news:fc**************************@posting.google.c om... I've posted earlier a question regarding the call to GetCommState. Here is the code for the function. The problem is that GetCommState always returns false!!
You shouldn't have to guess. _Immediately_ after the function returns, call GetLastError().
Now, I haven't researched it, but if IJW is trampling on the thread's last Win32 error by making some intervening Win32 API call, take a look at this:
http://blogs.msdn.com/adam_nathan/ar.../25/56643.aspx
Just by the way, is the LPT port in question controlled by a printer driver?
Regards, Will
And, finally i've fixed it!
The LPT port doesn't support all of the function in this code.
They all work for COM ports.
For LPT use just CreateFile, WriteFile.
"William DePalo [MVP VC++]" <wi***********@mvps.org> wrote in message news:<OG**************@TK2MSFTNGP12.phx.gbl>... "CeZaR" <pa****@go.ro> wrote in message news:fc**************************@posting.google.c om... I've posted earlier a question regarding the call to GetCommState. Here is the code for the function. The problem is that GetCommState always returns false!!
You shouldn't have to guess. _Immediately_ after the function returns, call GetLastError().
Now, I haven't researched it, but if IJW is trampling on the thread's last Win32 error by making some intervening Win32 API call, take a look at this:
http://blogs.msdn.com/adam_nathan/ar.../25/56643.aspx
Just by the way, is the LPT port in question controlled by a printer driver?
Regards, Will
I've stopped the spooler service before running the program.
Then i call CreateFile with "\\\\.\\NONSPOOLED_LPT1".
BTW GetLastError returns 2 -> Invalid function.
"William DePalo [MVP VC++]" <wi***********@mvps.org> wrote in message news:<OG**************@TK2MSFTNGP12.phx.gbl>... "CeZaR" <pa****@go.ro> wrote in message news:fc**************************@posting.google.c om... I've posted earlier a question regarding the call to GetCommState. Here is the code for the function. The problem is that GetCommState always returns false!!
You shouldn't have to guess. _Immediately_ after the function returns, call GetLastError().
Now, I haven't researched it, but if IJW is trampling on the thread's last Win32 error by making some intervening Win32 API call, take a look at this:
http://blogs.msdn.com/adam_nathan/ar.../25/56643.aspx
Just by the way, is the LPT port in question controlled by a printer driver?
Regards, Will
And, finally i've fixed it!
The LPT port doesn't support all of the function in this code.
They all work for COM ports.
For LPT use just CreateFile, WriteFile.
"William DePalo [MVP VC++]" <wi***********@mvps.org> wrote in message news:<OG**************@TK2MSFTNGP12.phx.gbl>... "CeZaR" <pa****@go.ro> wrote in message news:fc**************************@posting.google.c om... I've posted earlier a question regarding the call to GetCommState. Here is the code for the function. The problem is that GetCommState always returns false!!
You shouldn't have to guess. _Immediately_ after the function returns, call GetLastError().
Now, I haven't researched it, but if IJW is trampling on the thread's last Win32 error by making some intervening Win32 API call, take a look at this:
http://blogs.msdn.com/adam_nathan/ar.../25/56643.aspx
Just by the way, is the LPT port in question controlled by a printer driver?
Regards, Will This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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