There's a simulator built into the Concept programming software for Momentum, TSX Compact, Quantum & Atrium PLC's. Note that this is for the IEC language only; it will not work with 984 Ladder Logic. I understand ProWorx32 will have a 984 simulator built into it when it is released later this year.
The PlcSim32 from Concept package Can emulate any of Compact, Momentum & Quantum PLCs. You can program the PLC from Concept(or Modsoft, or
Proworx) and see what happens while you running the program. The interface is Modbus/TCP.
If you look for an emulator for momentum CPU, you have the Simulator 32Bits delivered with Concept V2.X.
Now if you want to simlate I/O momentum, from my knowledge there is no simulator available.
Anyway if you use peer cop or I/O Scanner the values put in the words are sent by the LC to the I/O so you don't need an emulator.