Outputting Signals from a Multisim Simulation to a NI DAQ Device

Overview

This example program is part of a series of LabVIEW based virtual instruments that can be used from inside Multisim.  All instruments are based on the virtual instruments templates you can find in your Multisim’s sample folder. There are two main categories of instruments:

• Input Instrument; takes simulation data from your schematic and processes them in the virtual instrument (e.g. custom display, specific analysis, output to real world).
• Output Instrument; inputs signals to a Multisim schematic to drive a simulation (e.g. acquire data from real world I/O, custom and arbitrary waveforms).

 

Notes for using real world I/Os with SPICE circuits

Due to the nature of SPICE, all real world data that will be used to drive a circuit need to be acquired before a simulation is started. Data output to a real world device can be done while simulation is running, however continuous updates can’t happen in real-time, as SPICE simulations don’t have a real-time timebase.

 

Purpose Of This Instrument

When design a new circuitry it is helpful to know how its output signal levels will work with already existing components. The LabVIEW based instrument Voltage Generator allows you to connect to two analog output channels of any dataacquisition device supported by the NI DAQmx driver, including Multifunction IO boards and USB devices. Running a virtual prototype together with its real world counterparts can help to improve the design in general and shorten the overall design cycle.

Installation Instruction

Unpack the archive to the Multisim installation directory. The table illustrates the files that will be copied to your harddrive.

Type	Name	Location	Application
Instrument	Voltage_Generator.llb	..\lvinstruments	Multisim
Example	Test Voltage Generator.ms10	..\ samples\LabVIEW Instruments\Voltage Generator	Multisim
Project	Voltage Generator.lvproj	..\ samples\LabVIEW Instruments\Voltage Generator	LabVIEW
Source	Voltage Generator.llb	..\ samples\LabVIEW Instruments\Voltage Generator	LabVIEW

 

Instrument Features

The Voltage Generator features tip strips for all controls. Hover with your mouse cursor over any of the controls and specific information will be displayed.

The Voltage Generator instrument is ment to be used with NI Multifunction DAQ boards and uses software timed single point updates. The instrument not suitable to do high frequency or continuous waveform analog outputs.

The following describes the function of the various controls

• Sample Rate (Hz) specifies the sampling rate in samples per channel per second.
• The Graph displays data wired to the instrument’s input pins
• Channel A and Channel B specify the name of the physical channels from a particular DAQ device you like to output to. Select channels from the drop down list or enter channel string manually (e.g. Dev1/ao0).
• Update Rate (Hz) specifies your desired update rate in Hz. Actual update rate may vary as the update of multifunction DAQ boards analog outputs is software timed.
• The Meter displays voltage level of the currently performed update
• Actual Update Rate (Hz) indicates the actually achieved update rate in Hz. Update rate may vary as the update of multifunction DAQ boards analog outputs is software timed.
• Max. Hzand Min. Hz indicated the maximum and minimum achieved update rate in Hz.
• Reset triggers to restart the recording of Max. Hz and Min. Hz

  

 

How To Use This Instrument

If you are familiar with Dataacquisition from National Instrument, you will find it easy to use the Voltage Generator instrument. However, here are some simple steps we recommend to follow when using the Voltage Generator for the first time.

1. Verify a NI DAQ device is connected to or plugged into your computer
2. Open Multisim and create your circuit
3. Add the Voltage Generator to your schematic
   1. Access the Voltage Generator from the instrument toolbar
   2. Place it on your schematic
   3. Wire it to the desired net
4. Output voltages to DAQ device
   1. Double click the instrument symbol to open the interface
   2. Enter the channels you like to update
   3. Set Update Rate (Hz)
5. Start the simulation
   1. Change channels, Update Rate (Hz) or reset Max. Hz and Min. Hz if necessary

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Additional Resources

Search ni.com for more LabVIEW based instruments for NI Multisim

Tutorial on "How To Create A LabVIEW Based Instrument For NI Multisim"

Tutorial on "Assure Compatibility of LabVIEW based Instruments across different NI Multisim versions"

Learn more about NI Dataacquisition

 

Note: You only need NI LabVIEW to create or edit and an instrument. NI LabVIEW doesn’t need to be installed on the machine where you intend to run Multisim.

Requirements

Filename: voltage_generator.zip

Software Requirements

Application Software: LabVIEW Base Development System 8.2, Multisim Base Edition 9.x
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Multifunction DAQ (MIO)
Driver: NI-DAQmx 8.0

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