Let me clarify. It's not impossible to to simulate signals with LabVIEW and NI-Max. The problem is the limited scope of the simulated signal. For example, say you have a motor connected to a rotary encoder. You have hardware that controls the motor speed, but your motor and encoder have a 10 week lead time. You probably won't find anything in NI-Max or LabVIEW to simulate the encoder input to your program. The encoder signal will track the speed command and NI-Max doesn't know that. It might only give you a fixed frequency. Your boss wants the program in 12 weeks.
With the type of model I use, you call the model instead of the DAQ device. The model looks at the command you've sent to the motor control and computes the response of the motor and encoder. The model uses the computed response to build simulated waveforms that it presents as acquired data. The program doesn't know the difference, so you can debug control algorithms, data storage, operator interfaces, and many other aspects of your program without having the complete system.
Yes, it's more work "up front," but it allows you to get much closer to an operating program while you wait for parts or for your technicians to wire the system.
