i have been working on an iso8583 payment card parsing library for time.
its written in erlang but can be used in erlang,elixir,lfe,etc.. basically all beam languages. this library can be used for packing and unpacking iso8583 financial messages.
It accepts a specification file which contains info about fields,mti,bitmap for your messages. The specification has info such as header length for various fields,padding info for fields,etc… This specification information is then used for packing/unpacking iso8583 formatted payment card messages.
it can be found on hex or github take it out for a spin and let me know how you find it !!.