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Operating Systems Linux Debian Reading data from a serial port Post 302919881 by wisecracker on Sunday 5th of October 2014 09:26:20 AM
Old 10-05-2014
Sometimes a serial transfer can be a RPITA...
There is usually a buffer of _at_least_ 256 bytes to fill first, so........
........try this sequence of events as a starter test mode from root TO assume a 3 wire system only:-
(RTS and CTS should be ignored using the below.)
Code:
1) Close down your terminal completely and do a reboot of your machine.
2) In root mode open up a new terminal then...
3) Number 4) below is optional...
4) chmod 666 /dev/ttyS0
5) Check the status of your /dev/ttyS0
6) Note that your stty might need -f instead of -F and may already be at 9600bps...
7) stty -F /dev/ttyS0
8) Set up the on board serial I/O to 9600bps and RAW data transfer, in my case, for PCLinuxOS and Debian.
9) Again note that your stty might need -f instead of -F ...
10) stty -F /dev/ttyS0 9600
11) stty -F /dev/ttyS0 raw
12) Finally, again check the status of your /dev/ttyS0
13) And again, note that your stty might need -f instead of -F ...
14) stty -F /dev/ttyS0
15) Now start printing, (blocks of?), characters to the terminal window...
16) cat < /dev/ttyS0
17) It might take a second or so to fill your default serial buffer and may display a 256 byte  burst on each access so be aware.

Hope this works for you...
 

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DIO_TCSETATTR(3)							 1							  DIO_TCSETATTR(3)

dio_tcsetattr - Sets terminal attributes and baud rate for a serial port

SYNOPSIS
bool dio_tcsetattr (resource $fd, array $options) DESCRIPTION
dio_tcsetattr(3) sets the terminal attributes and baud rate of the open $fd. PARAMETERS
o $fd - The file descriptor returned by dio_open(3). o $options - The currently available options are: o 'baud' - baud rate of the port - can be 38400,19200,9600,4800,2400,1800, 1200,600,300,200,150,134,110,75 or 50, default value is 9600. o 'bits' - data bits - can be 8,7,6 or 5. Default value is 8. o 'stop' - stop bits - can be 1 or 2. Default value is 1. o 'parity' - can be 0,1 or 2. Default value is 0. RETURN VALUES
No value is returned. EXAMPLES
Example #1 Setting the baud rate on a serial port <?php $fd = dio_open('/dev/ttyS0', O_RDWR | O_NOCTTY | O_NONBLOCK); dio_fcntl($fd, F_SETFL, O_SYNC); dio_tcsetattr($fd, array( 'baud' => 9600, 'bits' => 8, 'stop' => 1, 'parity' => 0 )); while (1) { $data = dio_read($fd, 256); if ($data) { echo $data; } } ?> NOTES
Note This function is not implemented on Windows platforms. PHP Documentation Group DIO_TCSETATTR(3)
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