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How to read the RS-232 lines?

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Contributed by Anonymous Monk on Oct 02, 2000 at 11:11 UTC
Q&A  > input and output


Description:

I am trying to read input from the serial port from a tone-decoding PIC controller, but so far have failed miserably. The incoming number is 6 digits long. Any ideas or examples I might have look at will be most welcome.

Answer: How to read the RS-232 lines?
contributed by kb2yht

I use Device::SerialPort for talking to the PIC UART:

use Device::SerialPort; my $port = Device::SerialPort->new( "/dev/ttyS0" ); $port->baudrate(9600); $port->databits(8); $port->stopbits(1); $port->parity("none"); my $string = ''; my $more = 1; while($more) { my $pass = $port->write('S$'); my $end_seen = 0; while ( not $end_seen ) { local $_ = $port->input; if ( $_ ne '' ) { if ( m/S:/ ) { # string start $string = $_; } elsif ( m/:$/ ) { # string end $string .= $_; print $string; # deal with the final string $end_seen=1; $more=0; } else { $string .= $_; } } } }
Be warned - If you are trying to get something out cleanly in one try, it will probably not work. I found that I have to interrogate the PIC over and over to keep the UART alive and talking to me.
Answer: How to read the RS-232 lines?
contributed by Anonymous Monk

There is Win32API::CommPort.
Once upon a time I used to write testbed code for hardware I designed. Generally the system control and monitoring was all done on RS-232 ports. We were using Windows, and for at least the last 5 or 6 years that I can recall we always did our testing in the lab with Perl.

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