IOCTL

This program opens a tty (serial port) and then calls ioctl with the fd of the serial port, the command TIOCMGET (listed as get the status of modem bits) and a pointer to an integer into which the result is returned.

Reference:

http://www.linuxjournal.com/article/6908

http://www.kernel.org/doc/man-pages/online/pages/man2/ioctl.2.html

chines: http://www.vr.ncue.edu.tw/esa/EmbeddedSystemProgramming2010/ch06.htm

Uart intro: http://digital.ni.com/public.nsf/allkb/4CFF7C3555A421F78625705D002AFCF4