Echelon i.LON SmartServer 2.0 - Manual (Page 242)

228 Appendix A - Programmer’s Reference
int nBytesRead = ReadBytes(RS232_fd, rxBuf, MAX_RX_BYTE_SIZE);
//check whether something has been read
if (nBytesRead >= 1)
{
printf ("Read %c from RS232\n", Line1);
//if something has been read, write it to display device
rs232_write(RS232_fd, (Byte *)rxBuf, nBytesRead);
}
}
}
int CRs232Driver::ReadBytes(HANDLE handle, Byte* buffer,
int bytesToRead) const
{
fd_set readFds;
FD_ZERO(&readFds);
FD_SET(handle, &readFds);
Timeval readTimeout;
readTimeout.tv_sec = 0;
readTimeout.tv_usec = 0; //return immediately if no data is
//available
int nResult = select(handle+1, &readFds, NULL, NULL,
&readTimeout);
if(!nResult || nResult == ERROR)
return nResult;
if(!BytesReadyForRead(handle))
return ERROR;
return rs232_read(handle, buffer, bytesToRead );
}
int CRs232Driver::BytesReadyForRead(HANDLE handle)const
{
int bytesAvailable;
ioctl(handle, FIONREAD, (int) &bytesAvailable );
return bytesAvailable;
}
rs232_write()
You can use the rs232_write()method in the OnTimer()routine to write data to the RS-232
interface.
SYNTAX
int rs232_write(int fd, unsigned char * buf, int length);
The fd parameter specifies the file handle returned when the RS-232 interface was opened with
the rs232_open() method.