From your description, it seems like the smart panel is a device that operates at a pretty low level, and doesn't understand HTTP or another common net protocol.
It may be easier for you to write the "connect to smart panel" piece in a different language if you have a better grasp of it (e.g. C, asm) than perl.
However, for the manipulating and processing part, perl's your man :-)

If you're (or wanting to be) writing files containing the panel's data, perl can easily read those in and manipulate them to your heart's content. Depending on the type of file, you could use DBI and DBD::CSV for comma delimited files, or split on some simple string or pattern.
As for graphing options, I'd recommend sitting down with the book "Programming Web Graphics with Perl and GNU Software". Despite its title, it's a good review of many of perl's graphics modules in general, and has a chapter devoted to programming graphs using gifgraph.