Interfacing instruments in simulation mode

[Amit Darwhekar]

Dear All,

I have to interface Fluke/Wavetek wt30x signal generator and HP 34401a digital multimeter in the simulation mode. I have been asked to design an experiment where frequency response of an amplifier will be plotted based on the input from the function generator. At the same time, for reading values generated by the function generator, HP 34401a DMM should be interfaced with it. However, this task should be accomplished using the drivers in simulation mode for above mentioned instruments . I have already configured the respective drivers in simulation mode using MAX and have created VIs for them. However, to interface these drivers to each other, I cannot find VIs that can read or write data from one instrument driver to the other. So, is it at all possible to interface instruments in simulation mode?

Your help is highly appreciated.

With regards,

Amit

[Scott_G]

Hey Amit,

I am a little bit confused about what you are trying to do here.  Are you trying to plot the input of the function generator against the ouput of the multimeter readings to compare the relationship between the 2?  If this is the case, you would want to program that in LV and you wouldn't really need the instruments to communicate with each other.  Do you know what information you are trying to pass between the 2 devices? 

[Amit Darwhekar]

Dear Mr. Scott,

Thank you for your response and valuable guidance. I have cross checked requirements of the experiment and have found that output of the function generator will go to the amplifier circuit. The output of amplifier circuit is to be measured by using DMM. Based on these readings frequency response of the amplifier should be plotted. I apologize for the confusion.

However, both these instruments should be interfaced with a simulated amplifier ( I guess, I will have to use transfer function of an amplifier to simulate it). Since, none of the VIs, which we use for simulating a function generator, have output terminals (other than Instrument Handle Out and Error Out), it is very difficult to interface a simulated function generator with a simulated amplifier. E.g. we will need Vin and gain to compute Vout of an amplifier. But, since none of the VIs used for simulating function generator gives amplitude of the waveform as output, we do not get the required Vin. Similarly, in case of DMM, there is no input to any of the VIs, where we can interface the output of the amplifier circuit.

I would appreciate if you could verify my way of thinking and would guide me in this regard.

With regards,

Amit

[Dennis_Knutson]

There is no output connection available for the function generator functions because the purpose of the functions is to tell the function generator to physically output a signal - not create a software signal. The DMM read function has no input because the purpose of the DMM function is to tell the DMM to make a phycial measuremtn at it's input terminals - not take a software signal. IVI drivers in simulation mode are not designed to do what you want. IVI simulation mode is mostly intended for error checking. You can run a program through without it stopping because of error conditions but that is about the extent of it. The read functions do return a value but the values are not something you have much control over. The values returned can be whatever the author of the driver decides to do. I think in some cases, it's just the result of a random number generator. To do what you want, you would have to write your own simulation code. There are functions in LabVIEW to simulate a variety of signals and in fact, there are shipping examples that use simulated signals to demonstrate some of the functions.