Picking up on the "Any help appreciated" comment:

• Always use strictures (use strict; use warnings;)
• Use lexical file handles
• You only need to call binmode once
• Use Perl for loops to advantage - avoid indexing where it's not needed

so your code could look like:

use strict;
use warnings;

my $fn = "delme.bin";
my $bName = 'eps_cm_0_pblk1';
my %gBuf = (eps_cm_0_pblk1 => ['0x00000019', '0x0000001b']);

open my $binOut, '>', $fn or die "Couldn't open '$fn' for writing: $!n
+";
binmode $binOut;

foreach my $element (@{$gBuf{$bName}}) {
    print $binOut pack ('C', hex $element);
}

close $binOut;
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