We have a security system that logs peoples movements in and out of
certain doors.
The output of the movements will go to a device into which a parallel
lineflow printer is plugged in to.

Has anyone come across any software that would allow you to plug the
parallel cable into a computer and then have it interpret the printer
data and save it to a text file (or even better a database)?

I am struggling to come up with googlable terms to describe it... :/