Hi, Grant, I have written a simple program based on the POXIS programming guide, however, it seems that ioctl() function doesn't have a command of 'TIOCMGET'and 'TIOCMSET'. I am currently using Centos system. Do you know any other function which could control the serial port pin status? Error: serialIO.c:195: error: `TIOCMGET' undeclared (first use in this function) serialIO.c:195: error: (Each undeclared identifier is reported only once serialIO.c:195: error: for each function it appears in.) serialIO.c:207: error: `TIOCM_CD' undeclared (first use in this function) serialIO.c:208: error: `TIOCM_CTS' undeclared (first use in this function) serialIO.c:209: error: `TIOCM_DSR' undeclared (first use in this function) serialIO.c:210: error: `TIOCM_RI' undeclared (first use in this function) serialIO.c:212: error: `TIOCM_DTR' undeclared (first use in this function) serialIO.c:215: error: `TIOCM_RTS' undeclared (first use in this function) serialIO.c:223: error: `TIOCMSET' undeclared (first use in this function) -----Original Message----- From: linux-serial-owner@xxxxxxxxxxxxxxx [mailto:linux-serial-owner@xxxxxxxxxxxxxxx] On Behalf Of Grant Edwards Sent: 2008年10月3日 22:27 To: linux-serial@xxxxxxxxxxxxxxx Subject: Re: Help:Serial / Parallel Port Control Under Linux On 2008-10-03, johnny <johnny@xxxxxxxxxxxxxxx> wrote: > Right Now I need to write a simple C code to control the > serial / parallel port under linux working like this: Detect > there is an input signal / voltage change and send some output > signal / voltage accordingly, eg: if DSR is detected to be > high, I want to set RTS to be high as well; if RI is detected > to be high, I want DTR set to be low etc. > > I have read the Serial-How to and Serial programming-How to, > however I am still not so clear regarding to this simple > programming. Ignore the serial programming howto. It's out-of-date, incomplete, unmaintained and just plain wrong in many areas. I needs to be gotten rid of, but that doesn't seem to be possible. A far better source of information is the Serial Programming Guide for Posix Operating Systems: http://www.easysw.com/~mike/serial/serial.html Specifically, the information about modem control and status lines is in chapter 5.1: http://www.easysw.com/~mike/serial/serial.html#5_1 -- Grant Edwards grante Yow! Inside, I'm already at SOBBING! visi.com -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html