I think that the Logixpro simulator that chavak mentioned can be found at the Learning Pit ... it has a 15-day free trial period ... maybe it will answer some of your needs ... as he said, the RSLogix500 Emulator by Rockwell is not free ... you should contact your local distributor if you're interested in buying a copy ... keep in mind that you will also require RSLogix500 in order to program the Emulator ... be sure that you discuss this with your distributor before you place the order ...
suggestion: if you're just trying to learn, you'll probably get better results from buying an actual used processor (from E-bay, etc.) rather than using the software emulator package ...