in reply to
I need Hex conversion, not!
Here's a cut-down example of a pack approach to building a socket message. I leave you to fiddle with the checksum until it comes out right; I can never seem to get this sort of thing first-try.
>perl -wMstrict -le
"my $SM = 0xfe;
my @ADRDSTN = (0x00, 0x09, 0x01, 0x00);
my $MID = 0x01;
my $MDLH = 0x00;
my $MDLL = 0x18;
my $EM = 0xFD;
my @message = (@ADRDSTN, $MID, $MDLH, $MDLL);
my $packed_message = pack 'C*', @message;
my $checksum = 256 - unpack '%8C*', $packed_message;
my $msg_for_socket = pack 'C a* C C', $SM, $packed_message, $checksum
my $msg_for_debug = unpack 'H*', $msg_for_socket;