Any experience or software for Control Techniques FNC4? Wha do I replace it with?

[uli12us]

That depends what you want to do.
If you want to reuse the existing drives, you need the IP/A, if you want to change it for modern drives you can buy the IP/M. I don't know the prices,
but you need 100quid for one drive.
The new drives can be controlled with step/dir. But you must connect the encoder lines directly to the drives. They need to have an differrential (maybe single-ended is enough) TTL output. If you have another signal, then maybe you can change it, with special electronics. Or you must change it with an encoder from HP/avago.

Your drives are capable of a bit more then 60V and 3Amps continuous/ 6 Amps Peak for 1 second. So you need a brushed DC/Motor drive with not less then these amounts.

The only drives I found for my machine are Leadshine DCS810 or american Geckos, which are doubled as expensive.