Question

How were the franks connected to the Catholic Church

Answer 1

The connection was that the Franks and Catholic Church formed a partnership to rule the 'West'. the Church gave the Franks legitimacy and the backing of religion, the Franks gave the Church military and secular power so the Church would be obeyed and could get rid of any rivals. Hope this helps answers your question. 

Answer 2

They converted to Christianity and established ties to the church.