Thus, I need to open a port without using a module like Device::SerialPort.

What OS does the "device" run?

I don't really know :P how can I find out? By the way, the ports are RS232 serial ports, if that's of any importance.

Edit: It's a Linux operating system, kernel version 2.6.

From your OP and subsequent reply to BrowserUk, I get the impression that you are dealing with an embedded system of some kind, one that runs Linux and already has Perl installed. If so, is there any 'native' way to transfer a file onto this system? (How do you 'talk' to this board?) If a file or files can be transferred to the system, cannot the file or files that comprise Device::SerialPort be transferred in this way and installed by hand? See Yes, even you can use CPAN.

I have been able to use Device::SerialPort to communicate with an X11 home automation system. However, I ended up using a usb to serial converter as my netbook did not have a serial port connection. I run Ubuntu on my netbook, so I cannot comment on a windows system. Have a look at the article on doing this PDF from linux magazine

Best regards
Ty

I suppose your "complicated reason" for not using Device::SerialPort is that you would need to cross-compile the XS part to ARM. I'm not sure why XS is used here but I suspect it may be about signal handling or some timing issue. I haven't tried this in Perl but it looks fairly straightforward.

Yeah that sounds exactly like it :P one of the employees explained it to me, but due to my lack of expertise in programming I didn't fully understand it.

Thanks also for your link. I tried it, but that program crashes for me (when running that piece of code the program freezes). Now, I came across another piece of code which seems to connect just fine (no error) but which does not properly send or receive any messages. Good thing to know is that when the boards receive a message they reply to it, even when the message sent is completely random. So it's likely that the sending part isn't properly functioning... Here is the code to set up the port:

my $PORT = "/dev/ttyS0";
system ("baud=19200 stop=1 data=8 parity=n");
open DEV,"+<$PORT" or die "Failed to open port\n";
my $ofh = select(DEV); $| = 0; $/='>'; select($ofh);
[download]

And here to send one of the 4 byte package and receive the output (and since there is no output, the program freezes there). This message is directed at the first board (that's why @data1 = 1).

my @data = (3, 1, 255, 253);                
my $packeddata = pack("C*", @data);

print DEV $packeddata;

my $output = <DEV>;
#print "Output: $output ";
[download]

Thanks for all the replies so far! Let's hope we can solve this!

You can check if the write succeeded by testing the return value of print. e.g. die $! unless print DEV $packeddata;