After you configure the IVI driver with the IVI features you want state caching, range checking, simulation, status checking, or recording coercions you continue developing an application as you do with a traditional LabVIEW instrument driver. Contributed instrument drivers are not supported by National Instruments or other third parties. This is the second level of simulation that you can use with IVI drivers. In Figure 7 , notice that the sessions to the DCVoltage interface and to the driver session are closed after they are used. This document describes how to use the IviDmm class driver with the hpa and fl45 specific drivers; however, you can use these instructions as a guideline for using other examples and drivers.
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When you make calls to a class driver, the class driver then calls the specific driver to perform its function. From your test program, you make calls to the class drivers, which in turn communicate through the specific drivers for your instruments.
To test a new instrument feature before you purchase that instrument by installing its IVI driver and running a test program to ensure that the instrument provides the functionality that you want.
Otherwise, select Don’t Simulate and create a new hardware asset under the Hardware tab. The only way to get one of these handles is from the instrument Initialize function which only succeeds if the instrument is connected.
Back to Top 4. They point to driver sessions and allow for interchangeability.
ifi Because you have access to this source code, you are free to modify the driver C code to add your own data generation algorithms to generate simulated data that more closely applies to the UUT or the application on which you are working. One of these attributes is simulation. You set up virtual channel names in the properties of a driver session.
Getting Started Using National Instruments IVI with LabVIEW or LabWindows/CVI
Note If the actual instruments are connected to your system, you can run the same examples with simulation disabled. To enable one of the IVI features, you set its value to 1 in the option string.
You should consider all driver choices available, and choose the driver that best fits your needs. This is typically the first interface in the list. The IVI Engine uses these settings when it runs your test application. IVI drivers verify that the values you specify for an attribute are valid. Users build their programs by calling the standard functions in the class drivers. It is redundant to send the other four settings each time you run the VI.
Therefore, you do not have to have the instrument connected to the computer to perform range checking. IVI drivers provide this information and verify the entries you have made if you enable Range Checking.
The class interface changes and a new set of properties and methods are now selectable, shown in Figure 6. Make sure the option string is empty when you use the MAX approach.
Before discussing the technical details of how simulation works, it is important that you have a clear understanding of the various levels of simulation possible with instruments. Rate this document Select a Rating 1 – Poor 2 3 4 5 – Excellent. For example, with IVI all function generator drivers have the same programmatic interface for basic instrument functionality.
Instrument drivers specify the instrument driver DLL while the hardware asset properties specify the resource name to access a physical device. Rate this document Select a Rating 1 – Poor 2 3 4 5 – Excellent. By providing high-level VIs for programming, they eliminate the need for application developers to learn complex programming protocols. Calls to these high-level VIs often result in transmission of redundant commands to the instrument.
With IVI drivers, you can check the status of an instrument after every function that interacts with the instrument without adding extra VI calls. Ifi internal structure Sets programmatic interface of similar instruments Divides instruments into functional classes such as oscilloscopes and digital multimeters Establishes the characteristics of each class of instruments The IVI Foundation also specifies the programmatic interface for these different classes of instruments.
Using IVI Drivers in LabVIEW – National Instruments
The IVI Engine then uses the configuration parameters associated with the fl45 driver session when it executes your application. Simply replace the resource name string with fl When used in labviw mode, the simulation automatically returns data to the program without requiring user interaction. Back to Top 5.
This virtual approach allows you to set up a number of different instrument driver configurations that test applications can easily access using the resource name string.
A dialog box appears, shown in Figure 1.