From: Ned Konz <ned@...>
Date: 2001-12-20T02:14:07+09:00
Subject: [ruby-talk:28964] Re: Can't  obtain data from Serial Port.

On Wednesday 19 December 2001 06:47 am, Vlad wrote:

> I try to write the simple program allowing exchanging packages through
> Serial Port with POS Terminal.

> The code "ENQ" really comes in POS and it answers in Serial Port, but I
> can not receive it. Whether I can use here for this purpose IOCTL?
> If not it is difficult, write an example of use of function IOCTL c
> FIONREAD and TIOCMGET in parameters.

Look at termios (in the RAA). Here's a program I recently wrote (note the 
need to open it and reopen it after setting the parameters):

require 'termios'

DEVICE = '/dev/ttyS1'
BAUDRATE = Termios::B19200

# first open non-blocking to set the modes
dev = File.open(DEVICE, File::RDWR | File::NONBLOCK)
# set up the modes we want
newtio = Termios::new_termios()
newtio.c_iflag = Termios::IGNPAR
newtio.c_cflag = Termios::CS8 | Termios::CREAD
newtio.c_cc[Termios::VTIME] = 0		# timeout in deciseconds
newtio.c_cc[Termios::VMIN]  = 1		# 1 char min for read (block)
newtio.c_ispeed = newtio.c_ospeed = BAUDRATE

Termios::setattr(dev, Termios::TCSANOW, newtio)

# then reopen
dev.close
dev = File.open(DEVICE, File::RDWR)
Termios::flush(dev, Termios::TCIOFLUSH)

$stdout.sync = 1

loop {
	dev.print("C\r")
	line = dev.readline
	# CS=3 CT=10 V=13.175 %=100 bl= 0 SS=1 ST=14 SD=0 or= 0
	unless line =~ /CS=(\S+) CT=(\S+) V=(\S+) %=(\S+) bl=\s*(\S+)/
		$stderr.puts("bad line: " + line)
	end
	printf("\"%s\",%s,%s,%s,%s,%s\n", Time.now.to_s, $1, $2, $3, $4, $5)
	sleep 60
}

-- 
Ned Konz
currently: Stanwood, WA
email:     ned@bike-nomad.com
homepage:  http://bike-nomad.com