Unregistered

Below I have pasted my program. The purpose of the program is to read data from a serial port (in this case COM2) and print it out to the screen. I can't seem to get it to print to the screen. I don't know if the port is really configured properly. Can someone out there take a look at my code and run it to see what the problem is? Thnx in advance! Rachael

#include <windows.h>
#include <string.h>
#include <memory.h>
#include <commdlg.h>
#include <io.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX 130

// Flow control flaags
#define FC_DTRDSR 0x01
#define FC_RTSCTS 0x02
#define FC_XONXOFF 0x04

char port[5] = "COM2:" ; /* Comm port name. */
char msg[MAX] ; /* Message received from port. */
int n_msg = 0 ; /* Counts bytes to read. */
int n_in ; /* Counts bytes read. */
int ok ; /* Return code from function calls. */
HANDLE hPort ; /* Handle to IO port object. */
DCB dcb ;
COMMTIMEOUTS CommTimeOuts ;
BYTE bSet ;


int main(void) {

// Open comm port
hPort = CreateFile(port,
GENERIC_READ,
0,
NULL,
OPEN_EXISTING,
0,
NULL) ;

if (hPort == INVALID_HANDLE_VALUE) {
printf("Cannot open IO port (error %d)\n", GetLastError()) ;
return 1 ;
}

// Setup comm port connection
dcb.DCBlength = sizeof(dcb) ;

GetCommState(hPort, &dcb) ;

dcb.BaudRate = 9600 ;
dcb.ByteSize = 8 ;
dcb.Parity = 0 ;
dcb.StopBits = 1 ;

// setup hardware flow control

bSet = (BYTE) ((FC_XONXOFF & FC_DTRDSR) != 0) ;
dcb.fOutxDsrFlow = bSet ;
if (bSet)
dcb.fDtrControl = DTR_CONTROL_HANDSHAKE ;
else
dcb.fDtrControl = DTR_CONTROL_ENABLE ;

bSet = (BYTE) ((FC_XONXOFF & FC_RTSCTS) != 0) ;
dcb.fOutxCtsFlow = bSet ;
if (bSet)
dcb.fRtsControl = RTS_CONTROL_HANDSHAKE ;
else
dcb.fRtsControl = RTS_CONTROL_ENABLE ;

// setup software flow control

bSet = (BYTE) ((FC_XONXOFF & FC_XONXOFF) != 0) ;

dcb.fInX = dcb.fOutX = bSet ;

dcb.XonChar = 0x11 ;
dcb.XoffChar = 0x13 ;
dcb.XonLim = 100 ;
dcb.XoffLim = 100 ;
dcb.fBinary = TRUE ;
dcb.fParity = TRUE ;

SetCommState(hPort, &dcb) ;

// read data from port
do {
n_msg = (n_msg <= MAX ? n_msg : MAX) ;
ok = ReadFile(hPort, msg, n_msg, &n_in, NULL) ;
printf("%s", msg) ;
} while(ok) ;

if (!ok) {
printf("Cannot read message (error %d)\n", GetLastError()) ;
return 1 ;
}

// Cleanup
ok = CloseHandle(hPort) ;
if (!ok) {
printf("Cannot close port handle (error %d)\n", GetLastError()) ;
}

return 0 ;
}

Unregistered

Is this code so specialized that there are no C and win32 experts out there...if you're out there please look at my code to see why I can't seem to read data from a serial port. Thanks!
Rachael

Fordy

It's not that the problem is difficult............personally I have no way to test your code as the com port on my computer is redundant.......I think there's a small spider living in there at the moment and he's welcome to it! Go USB!!!!


Oh...and by the way....didnt you post this question a few days ago but under the name "Fred"?

__________________
"If A is success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut."
Albert Einstein (1879 - 1955)

Board Rules

Unregistered

No, but I did use your link to develop this program. Anyway, I rewrote the code based off of information from the MSDN website and fixed the problem. Rachael