TTL to HTL signal conversion

Hello Group!

I have a couple of old servodrives with step/direction
inputs, but they use HTL signals, logic high is 24v
instead of 5v.
I want to be able to connect these to the parallell port,
and therefor need some converter.
Is there anybody that have some schematics or ideas for
a preferably opto isolated 5v to 24v and 24v to 5v converter.

Best Regards!
Lars Levin