I only count 43 per line, could this be a source of your problems? There are many ways to do this, for example using regular expressions: 

use strict;
use warnings;
while(<DATA>){
  s/(.)(.{15})(.{14})(.{13})/$1,$2,$3,$4/;
  print;
}
__DATA__
0123456789012345678901234567890123456789012
C4432882490H019000020150211ESL6690 0H2015PC
C4833076550HC0P0000201412093J46651 0H2015DX
C6033106980H057130020150323FRE7602 0H2015PC
C663160140MT007015G20141124274847A MT2015PC

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In reply to Re: Unpack or substr to create CSV? by hdb
in thread Unpack or substr to create CSV? by johnmck

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