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Full Discussion: Writing to a Serial Port
Top Forums Web Development Writing to a Serial Port Post 302924586 by Meow613 on Monday 10th of November 2014 11:31:49 PM
Old 11-11-2014
I think I have solved two of the problems...

1]that the code was not consistent in its behaviour. I noticed it would only run when minicom was running; ie the COM port was not consistently configured.. This code fixed the problem
Code:
system("stty 9600 cs7 -parodd -cstopb < /dev/ttyS0");

2] The PHP script and C program were not communicating properly. The C program was being called from within a PHP script. The C program wrote to the port and read the output. The PHP script formatted and displayed the output. So... called the PHP script as the last line in the C program.

One problem remains..

I am still, regretably, having problems in writing to the scale.

Code:
setvbuf(fp1, NULL, _IONBF, 0);
fprintf(fp1, "%s","W\r\n");
memset(buf, 0, sizeof(buf));

No matter what I do, if the weight on the scale is changed, the C program has to run twice before it outputs the change of weight.
 

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EXIT(3) 								 1								   EXIT(3)

exit - Output a message and terminate the current script

SYNOPSIS
void exit ([string $status]) DESCRIPTION
void exit (int $status) Terminates execution of the script. Shutdown functions and object destructors will always be executed even if exit is called. exit is a language construct and it can be called without parentheses if no $status is passed. PARAMETERS
o $status - If $status is a string, this function prints the $status just before exiting. If $status is an integer, that value will be used as the exit status and not printed. Exit statuses should be in the range 0 to 254, the exit status 255 is reserved by PHP and shall not be used. The status 0 is used to terminate the program successfully. Note PHP >= 4.2.0 does NOT print the $status if it is an integer. RETURN VALUES
No value is returned. EXAMPLES
Example #1 exit example <?php $filename = '/path/to/data-file'; $file = fopen($filename, 'r') or exit("unable to open file ($filename)"); ?> Example #2 exit status example <?php //exit program normally exit; exit(); exit(0); //exit with an error code exit(1); exit(0376); //octal ?> Example #3 Shutdown functions and destructors run regardless <?php class Foo { public function __destruct() { echo 'Destruct: ' . __METHOD__ . '()' . PHP_EOL; } } function shutdown() { echo 'Shutdown: ' . __FUNCTION__ . '()' . PHP_EOL; } $foo = new Foo(); register_shutdown_function('shutdown'); exit(); echo 'This will not be output.'; ?> The above example will output: Shutdown: shutdown() Destruct: Foo::__destruct() NOTES
Note Because this is a language construct and not a function, it cannot be called using variable functions. Note This language construct is equivalent to die(3). SEE ALSO
register_shutdown_function(3). PHP Documentation Group EXIT(3)
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