NI-myVirtualCircuit - Who needs hardware?

[Alex.T]

NI-myVirtualCircuit

An Exciting Addition

The new edition of Multisim, Multisim 2012, introduced a new and exciting feature which will be sure to revolutionise our design phase enormously; this new feature goes by the name of the  LabVIEW Co-simulation Terminals. LabVIEW Co-simulation Terminals (LCTs) allow us to directly access inputs and outputs of a Multisim simulated schematic via DBL precision numerics, which represent either Voltages or Currents, on our LabVIEW Block Diagrams.

So, what does this example do?

The attached project allows us to acquire real world signals from an NI-myDAQ, process the signals on a virtual circuit, then take the circuit response and loop the samples back through the NI-myDAQ's Analog Output (AO) terminals. It breaks the engineering fourth wall, so to speak. The main idea is this: If you've currently got two circuits and you're missing components to bridge the two together, the component bridge can be simulated using the NI-myDAQ, LabVIEW and Multisim.

As an example, if you want to test a filter you're designing and you're waiting for the components to arrive, you don't have to wait any longer; you can use the NI-myDAQ as a bridge for the time being. This not only gives you the chance to continue your development through very accurately simulating the response of a circuit you haven't physically built, but you can also very quickly fine tune component choices, or even save yourself some money. I've not seen any examples on using the LCTs at the moment, apart from the release NI Developer Zone Article at least; but I'm sure that soon more and more LabVIEW users are going to realise just what is possible now that we can start integrating both LabVIEW and Multisim in this way.

On the Block Diagram, I've described all of the design choices involved so that you can see whether they're suitable or not for your own applications. As ever, I'd really appreciate any feedback that you have. Remember, you can start modifying the Virtual Ciruit to hold your own components!

Instructions

1. Download and unzip myVirtualCircuit-Multisim2012-LabVIEW-2011SP1.zip
2. Open myVirtualCircuit-v2.vi
3. Select your Physical Input Channels and then run the VI. It'll ask you where to save a file to; name it whatever you like.
4. Hit 'Record Input Signals'. This is where we'll be taking real data from your connected circuitry on the AI0/AI1 inputs. The data will simultaneously be pushed into the simulated Multisim circuit.
5. Hit 'Stop Recording' once you're finished acquiring data. At this point, the acquired real data will still be under the processing stage in Multisim. Under the Multisim 12 Logo, you'll see a progress bar. Please be patient, as at this point Multisim will be very accurately calculating the response of the simulated circuit to your real world data.
6. Once Multisim's processing has finished, the progress bar will empty. The circuit response will be saved to the file you specified so that you can replay the response of the simulated circuit through your DAQ hardware even after myVirtualCircuit has been closed down.
7. Hit the Play Circuit Response button. This will output the circuit response from Multisim out through the NI-myDAQ. You can press this button over and over again.
   

Have fun!