Subject:
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Get/SetCommTimeouts
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Sun, 29 Feb 2004 17:46:08 GMT
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Viewed:
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4072 times
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I am trying to write a C program (using VC++ 6.0) to talk to RCX 2.0 on my
Win XP (Home Ed) box.
Everything seems to be OK except the get/set of Communication parameters. I
cannot understand why.
I have attached the minimal C program which does _not_ work (along with the
execution listing at the end).
It generates the "The parameter is incorrect" error.
Surprisingly it doesn't seem to matter since I can send and receive mesgs
just fine, even though the calls fail.
Any help will be highly appreciated.
TIA,
-- Shashank
/*************************************************************/
#include <windows.h>
#include <stdio.h>
#define DEBUG(x) do{printf x;}while(0)
#define LEGO_USB_TOWER "\\\\.\\LEGOTOWER1"
HANDLE UsbPort; /* used for USB comm */
char msg[255]; /* to hold the error mesg */
int show_error(int error_code)
{
int ret = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM +
FORMAT_MESSAGE_ARGUMENT_ARRAY,
(LPCVOID)"",
error_code,
0,
(LPTSTR)msg,
255,
(va_list *)NULL
);
return ret;
}
int OpenUsbPort()
{
int ret;
COMMTIMEOUTS timeout;
UsbPort = CreateFile(LEGO_USB_TOWER, GENERIC_READ | GENERIC_WRITE, 0, 0,
OPEN_EXISTING, 0, NULL);
if (UsbPort == INVALID_HANDLE_VALUE)
{int e;
e = GetLastError();
show_error(e);
DEBUG(("Error = %d, %s\n",e,msg));
return 1;
}
DEBUG(("HANDLE = %d\n",UsbPort));
ret = GetCommTimeouts(UsbPort,&timeout);
DEBUG(("GetCommTimeouts returns %d \n",ret));
if(ret == 0)
{int e;
e = GetLastError();
show_error(e);
DEBUG(("Error = %d, %s\n",e,msg));
}
timeout.ReadIntervalTimeout=100;
timeout.ReadTotalTimeoutConstant=100;
timeout.ReadTotalTimeoutMultiplier=0;
timeout.WriteTotalTimeoutConstant=0;
timeout.WriteTotalTimeoutMultiplier=0;
ret = SetCommTimeouts(UsbPort,&timeout);
DEBUG(("SetCommTimeouts returns %d \n",ret));
if(ret == 0)
{int e;
e = GetLastError();
show_error(e);
DEBUG(("Error = %d, %s\n",e,msg));
}
return(0);
}
int CloseUsbPort()
{
int result;
result = CloseHandle(UsbPort);
DEBUG(("CloseHandle = %d\n",result));
return result;
}
int main(int argc, char **argv)
{
if(OpenUsbPort()==0)
CloseUsbPort();
return 0;
}
/* --------------------------------------
C:\atest\comm\Debug>comm
HANDLE = 2024
GetCommTimeouts returns 0
Error = 87, The parameter is incorrect.
SetCommTimeouts returns 0
Error = 87, The parameter is incorrect.
CloseHandle = 1
C:\atest\comm\Debug>
-----------------------------------------*/
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Message has 1 Reply:
 | | Re: Get/SetCommTimeouts
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| "Shashank Date" <sdate@everestkc.net> wrote in message news:Htuzyn.6qG@lugnet.com... (...) parameters. I (...) The "SetCommTimeout" function only applies to "COMx" serial ports. You are trying to use it on a USB port! (21 years ago, 29-Feb-04, to lugnet.robotics.rcx)
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