Are you looking for a simulation server or an S7 driver for AHMI; AHMI does not have native drivers for S7 as yet. You might like to check out Snap 7; I haven't tried this yet but they have a server that responds as an S7 machine. I have been working on finding a 'free'' OPC server that AHMI will connect to but they don't allow free versions to connect using many Tags, the most I have found is 30 from a British company but I need a minimum of 50. The Micro edition is very limited in what you can do with it as you have found there isn't a simulator provided with it like S7 Professional.
best of luck
Dale