RS-422 For Controllogix

Hi,
I’m reconverting an old instrument to a PLC system using a controllogix technologic, but I got 2 old Ferranti encoder with a RS-422 protocol, Somebody know any module I can used for reading this RS-422?

Is it actually RS-422 communications? or rather just the specification for full differential line driver outputs?
If it's a regular A/Abar B/Bbar output encoder, it can connect directly to a 1756-HSC module.

Hi,
The encoder is a 35HA optical absolute encoder with 20 bits, the encoder receiver and transmitter conform to RS-422 with serial data in a standard UART format. For me will be nice if a can convert the RS-422 to SSI format, if I can not find a controllogix module RS-422 then probably I have to use a pic controller to convert in SSI format.

Given the fact that people use this as a rs-232 extender, I imagine you could find appropriate converters.