Watchdog restarts the board despite feeding

Hi all,
I have a weird problem. I will feed hardware watchdog every 10s for many
hours (5-26 hours) without a problem and then the board will reset. The
code to feed the watchdog will execute just fine, but watchdog will reset
anyway.

This is the c# code that feeds watchdog:
FileStream _stream = new FileStream("WDT1:", FileMode.Open);
_stream.WriteByte(1);
_stream.Close();
_log.Debug("Fed Watchdog");

And this is the code that gets called in wdt.dll (slightly changed from
original WDT driver):
DWORD WDT_Write(DWORD hOpenContext, LPCVOID pSourceBytes, DWORD
NumberOfBytes)
{
  RETAILMSG(1,(TEXT("WDT: Write\r\n")));
  unsigned char * pBytes = (unsigned char *) pSourceBytes;

  if (pSourceBytes == NULL)
  {
    DisableReset();
    RETAILMSG(1,(TEXT("WDT: pSourceBytes == NULL\r\n")));

  }
  else if (pBytes[0] == 0)
  {
    DisableReset();
    RETAILMSG(1,(TEXT("WDT: pBytes[0] == 0\r\n")));

  }
  else
  {
    FeedIt();
    RETAILMSG(1,(TEXT("WDT: pBytes[0] != 0\r\n")));
  }

  return TRUE;
}

Any ideas what is happening here?

Thank you,
Andreja

Hi Andreja,

doing exactly the same thing (same C# code) and feeding it every 10 sec.
I have no problem over days and months...
So there must be problem somerwhere else in your code or your hardware?

Is your code really feeding the watchdog at the time the restart happens?

Regards
Carsten