Choose the Right Interface to Control Instruments in LabWindows™/CVI

This document guides you through choosing the right connectivity interface to control and communicate with your instrument in LabWindows/CVI.

NI provides a wide array of instrument connectivity interfaces designed for different needs. Therefore, it is important to choose the proper one for your application. First, refer to the following flowchart to determine the correct method to control your instrument. Then, refer to the section corresponding to the flowchart number to learn more about the interface.

Connectivity Interfaces for Instrument Control

When getting started, NI recommends using an instrument driver. Instrument drivers save you development time and cost because you do not need to learn the programming protocol for each instrument. The two types of instrument drivers are described further in this document.

 

1. Use Plug and Play Instrument Driver

A LabWindows/CVI Plug and Play instrument driver is a set of ANSI C software routines exported from a DLL. You can call these instrument drivers from any development environment that supports calls into DLLs.

• Learn more about LabWindows/CVI Plug and Play instrument drivers
• Find and install LabWindows/CVI Plug and Play instrument drivers

 

2. Use IVI Instrument Driver

IVI drivers are DLL-based drivers developed in LabWindows/CVI that allow for simulation and instrument interchangeability. To achieve interchangeability, the IVI Foundation defines specifications for the following instrument classes: DMM, oscilloscope, arbitrary waveform/function generator, DC power supply, switch, power meter, spectrum analyzer, and RF signal generator. IVI drivers also provide additional benefits like instrument state caching for improved performance, multithread safety, and instrument attribute access.

• Learn more about IVI instrument drivers
• Find and install instrument IVI drivers

 

3. Modify Existing Instrument Driver

If an instrument driver doesn’t exist for your instrument but a similar driver exists, you can modify the existing driver to fit your application needs.

• Modify an instrument driver in LabWindows/CVI

 

4. Create Instrument Driver

If an instrument driver doesn’t exist for your instrument and there aren’t any similar drivers, you can create an instrument driver from the Instrument Driver Project Wizard.

• Create Plug and Play instrument driver in LabWindows/CVI
• Create IVI driver in LabWindows/CVI

 

5. Use NI-VISA API

NI-VISA is the NI standard I/O API for instrumentation programming. NI-VISA can control GPIB, serial, USB, Ethernet, PXI, or VXI instruments, making the appropriate driver calls based on the instrument type so you do not have to learn instrument-specific communication protocol.

• NI-VISA Programmer Reference Manual
• Example of message-based communication (Serial, Ethernet, or GPIB instruments)
• Example of register-based communication (PXI, VXI instruments)

 

6. Use NI-488.2 API

Use NI-4882 to develop and debug an application program for GPIB instruments. The NI-488.2 driver has high-level commands that automatically handle all bus management. Low-level commands are also available. LabWindows/CVI examples installed with the driver can be found in NI Example Finder.

• NI-488.2 User Manual

 

7. Use NI Device Driver

For NI modular instruments, use the device drivers provided by NI found in NI Driver Downloads. LabWindows/CVI examples installed with the driver can be found in NI Example Finder .

 

8. Submit Instrument Driver Request

If the Instrument Driver Network does not have the driver you need, you can submit an instrument driver request. These requests are monitored by the NI Instrument Driver group and are developed based on popular demand.