Re: GetCommState failed with error 87.
On 14 Apr., 17:01, "Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>
wrote:
"uvbaz" <uv...@stud.uni-karlsruhe.de> wrote in message
news:ec8b47a1-6f67-48ec-acf8-384ff18188d3@a9g2000prl.googlegroups.com...
Hi,
i'm trying to set the serial port.(XP SP2, Visual Studio 2005). I use
the example code from MSDN "configuring a communications resource".
CreateFile pass through, however GetCommState return 0.With
GetLastError(), i get the error number 87, which means
"ERROR_INVALID_PARAMETER The parameter is incorrect. "
I'm sure the serial port works, because i can use another program to
read/write through it.
Error 87 usually means you have made a simple programming mistake with the
parameters. Can you show the relevant lines of the code? It is very hard
to guess what is wrong if you do not show some code.
--
Scott McPhillips [VC++ MVP]
Sorry, i forgot to paste them.
#include <windows.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
char *pcCommPort = "COM1";
hCom = CreateFile( pcCommPort,
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // no security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // not overlapped I/O
NULL // hTemplate must be NULL for comm devices
);
if (hCom == INVALID_HANDLE_VALUE)
{
// Handle the error.
printf ("CreateFile failed with error %d.\n", GetLastError());
return (1);
}
// Build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm.
fSuccess = GetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
}
// Fill in DCB: 57,600 bps, 8 data bits, no parity, and 1 stop bit.
dcb.BaudRate = CBR_57600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit
fSuccess = SetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
}
printf ("Serial port %s successfully reconfigured.\n", pcCommPort);
return (0);
}