RsLinx Lite is available for download at
Rockwell Softwares Web Updates. Just select RsLinx Classic under Communications Products and click Lookup Products. Only RsLinx Lite can be downloaded for free.
I guess the real question is what are you planning to do with it?
RsLInx Lite comes free with most other Rockwell Software that requires communications.
But RsLinx by itself is pretty much useless unless you are trying to create a DDE/OPC server. If this is what you are trying to do you must have RsLinx Single Node, OEM, or Professional