use strict and warnings:

use diagnostics;

my $Address = 'A7:F0';
#takes the first two characters and stores them for later
$AddressOriginal = substr($Address, 0, 3);
#removes the first three characters leaving the later ## in the format
+ ##:##
$Address = substr($Address, 3, 2);
print "$Address\n";
#Test lines to make sure the above lines do their intended purpose
#print $Address . "\n";
#print $AddressOriginal . "\n";
#for($count = 1; $count <= $IDcount; $count++) {
    $hexval = sprintf("%02X\n", ($Address));
    $Address++;
    $Address1 = ($AddressOriginal . $hexval);
    #Test line to make sure the procedure completed its intended task
    print $Address1; 
#}

__END__

F0
Argument "F0" isn't numeric in sprintf at ... (#1)
    (W numeric) The indicated string was fed as an argument to an oper
+ator
    that expected a numeric value instead.  If you're fortunate the me
+ssage
    will identify which operator was so unfortunate.

A7:00
[download]

See also:

• hex