Configuring a Communications Resource

The following example opens a handle to COM1 and fills in a DCB structure with the current configuration. The DCB structure is then modified and used to reconfigure the device.

DCB dcb;
HANDLE hCom;
DWORD dwError;
BOOL fSuccess;

hCom = CreateFile("COM1",
GENERIC_READ | GENERIC_WRITE,
0, /* comm devices must be opened w/exclusive-access */
NULL, /* no security attrs */
OPEN_EXISTING, /* comm devices must use OPEN_EXISTING */
0, /* not overlapped I/O */
NULL /* hTemplate must be NULL for comm devices */
);

if (hCom == INVALID_HANDLE_VALUE) {
dwError = GetLastError();

/* handle error */
}

/*
* Omit the call to SetupComm to use the default queue sizes.
* Get the current configuration.
*/

fSuccess = GetCommState(hCom, &dcb);

if (!fSuccess) {
/* Handle the error. *
}

/* Fill in the DCB: baud=9600, 8 data bits, no parity, 1 stop bit. */

dcb.BaudRate = 9600;
dcb.ByteSize = 8;
dcb.Parity = NOPARITY;
dcb.StopBits = ONESTOPBIT;

fSuccess = SetCommState(hCom, &dcb);

if (!fSuccess) {
/* Handle the error. *
}

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