Transition from Traditional NI-DAQ (Legacy) to NI-DAQmx using ANSI C and LabWindows/CVI: Part Four


This is the final document in the four-part series, “Transitioning from Traditional NI-DAQ (Legacy) to NI-DAQmx Using ANSI C and NI LabWindows/CVI.” Refer to the “Links to Other Topics in This Series” section for the full series.


Accessing Help in NI-DAQmx

This series references two manuals that are shipped with NI-DAQmx.

  • NI-DAQmx Core Help – references the language-agnostic manual for NI-DAQmx. The NI-DAQmx Core Help explains NI-DAQmx concepts and provides background about the various features and capabilities of the driver. Refer to Start » Programs » National Instruments » NI-DAQ » NI-DAQmx Help to access this manual.
  • NI-DAQmx C Reference Help – references the manual for the DAQmx ANSI C API. This reference is specific to the C API and provides documentation for NI-DAQmx function calls. There are also concept topics specific to using the DAQmx ANSI C API. Part of the NI-DAQmx driver software, this manual is located at Start » All Programs » National Instruments » NI-DAQ » NI-DAQmx C Reference Help.

Notes for LabWindows/CVI Users

Function Panels and Enumerated Constants

National Instruments LabWindows/CVI works with NI-DAQmx function panels that have intuitive user interfaces and enumerated constants.



Figure 1. LabWindows/CVI Function Panel for DAQmxCfgTiming();

DAQmxAttributes Functionality

The DAQmx Set Attributes and DAQmx Get Attributes functions help you browse to low-level NI-DAQmx properties without having to search for the specific function call.


Figure 2. LabWindows/CVI DAQmx GetTaskAttribute();


For example, to get the number of channels in a LabWindows/CVI task, you can use the DAQmxGetTaskAttribute(); call and navigate to the “Number of Channels” attribute. The corresponding C function call from the NI-DAQmx C Reference Help is DAQmxGetTaskNumChans();.

DAQ Assistant

DAQ Assistant is an interactive tool you can use to graphically configure a customized task to incorporate into a LabWindows/CVI project. For more information, view “Using the DAQ Assistant in LabWindows/CVI.”

Scaling Is Now a Fully Supported Feature of NI-DAQmx

NI-DAQmx provides built-in scaling for most common transducers, sensors, and actuators. For example, when creating an analog input temperature channel, you can specify the type of transducer, such as a thermistor, RTD, or thermocouple, used to make the measurement when creating the channel. However, if NI-DAQmx does not explicitly support your transducer or actuator, you can create a scale that specifies how to convert from the prescaled units to the scaled units. For more information, refer to the Custom Scales help topic by selecting NI-DAQmx Help >> Key NI-DAQmx Concepts >> Custom Scales.

Programmatically Save Tasks to Measurement & Automation Explorer (MAX)

With NI-DAQmx Version 7.4 and later, you can create tasks programmatically and save them to MAX.

Simulated NI-DAQmx Devices

NI-DAQmx 7.4 and later supports creating and using simulated NI-DAQmx devices. You can create NI-DAQmx applications without having the devices installed in the system. For more information, refer to the “NI-DAQmx Simulated Devices” help topic under NI-DAQmx Help >> Key NI-DAQmx Concepts >> NI-DAQmx Simulated Devices .

Consistent Terminology

With NI-DAQmx, many of the terminal and signal names have been changed so that the names are easier to understand and more consistent across NI hardware and software products. This change in terminology is explained in “KnowledgeBase 2X7MTTN1: What Are the Terminology Changes in NI-DAQmx?

For a list of frequently asked questions, refer to “Answers to Frequently Asked Questions about NI-DAQmx and Traditional NI-DAQ (Legacy).”