Signal generator in simulation loop

[Vss]

hi,

I am a undergraduate mechanical engineering researcher in the University of Michigan. Now i am dealing with a project involving labview and simulation, and have a very simple question, which is about the singal generator in simulation loop. I have 2 options, one is the signal generators under "Control Design&Simulation", and this one works well; another one is the Simulate Signal block, which generates weird-looking signals all the time in the simulation loop no matter what kind of singal i defined. So if you know could you please tell me the reason why? and for the signal generators under "Control Design&Simulation", can i use it as a real signal generator in my project?

Another question is, i am gonna do a maths manipulation to 4 analog inputs, i mean, a maths expression that involves these 4 inputs as 4 variables and then generate a desired output. For this application, should i use "formula node" function or just "formula"? do they have any difference? and do they have any requirement on the inputs, i mean, can they work with analog inputs? Thanks a million!

Regards,
Xiaofei

[tbob]

I dont have the Control Design and Simulation package installed on my system, but I think I can help you anyway.  The simulation vi's are meant to help you code the rest of your program without have a real function generator to generate the signals.  You can test your math part on a simulated signal.

If you have a real function generator, you can use VISA (under Instrument I/O) or NI-FGEN (under Measurement I/O) to control your real function generator.  You will then need a DAQ card or something to capture t he waveform data from the function generator.

Is it necessary to have real generator for your project?  The simulated signlas work quite well.  Also, to simulate a signal, you can use the functions found in the Functions palette - Waveform - Analog Waveform - Waveform Generation.  Here you will find functions like  Basic Tone Generator, Multitone Generator, Sinewave generator, etc...  There is a help screen on how to use these functions.  You can generate complex waveforms by adding and multiplying different waveforms.

For the math part, to me it is a matter of preference wether you use a formula node or actual math functions to achieve the desired result.  One works as good as the other.  I don't like function nodes because it adds some text to a graphic language.  However, for complex formula's it may be easier to use the formula node.

I hope this answers your questions.

[Vss]

Thanks a lot! That makes sense.