nidaqmx Python API

The nidaqmx.system module provides a high-level interface for inspecting and interacting with the NI-DAQmx system configuration. It allows developers to programmatically discover hardware resources, such as devices and physical channels, and manage system-level entities like storage and watchdogs.

Key sub-modules include:

• collections: For managing groups of system objects.
• device: For interacting with specific NI-DAQmx devices.
• physical_channel: For accessing and configuring individual physical channels.
• storage: For managing system storage resources.
• watchdog: For interacting with system watchdog timers.

A Task is a collection of one or more virtual channels with timing, triggering, and other properties. It serves as the primary container for managing acquisition or generation operations.

import nidaqmx
with nidaqmx.Task() as task:
    pass

The nidaqmx.task module is the primary interface for creating and managing NI-DAQmx tasks. A Task represents a collection of DAQmx resources (such as analog inputs, digital outputs, or counters) configured to perform a specific operation like acquisition or generation.

Key areas of functionality within this module include:

• Task Channels: Configuring the specific hardware channels (e.g., AI0, AO1) that participate in the task.
• Task Collections: Managing groups of channels or resources.
• Task Triggering: Setting up hardware or software triggers to control the timing of task execution.

Virtual channels (or simply channels) are software entities that encapsulate a physical channel along with specific configuration like range, terminal configuration, and custom scaling.

A physical channel is a terminal or pin used to measure or generate signals. Every physical channel has a unique name following the NI-DAQmx naming convention (e.g., cDAQ1Mod4/ai0, Dev2/ao5, or Dev6/ctr3).

import nidaqmx

# Adding a single analog input voltage channel with a specific range
with nidaqmx.Task() as task:
    task.ai_channels.add_ai_voltage_chan("Dev1/ai0", min_val=-10.0, max_val=10.0)
    data = task.read()

# Adding multiple analog input voltage channels
with nidaqmx.Task() as task:
    task.ai_channels.add_ai_voltage_chan("Dev1/ai0", min_val=-5.0, max_val=5.0)
    task.ai_channels.add_ai_voltage_chan("Dev1/ai1", min_val=-10.0, max_val=10.0)
    data = task.read()

Timing controls when a signal is acquired or generated.

• Hardware Timing: Uses a digital signal (like a device clock) to control the rate. It is more accurate and can run much faster than software loops.
• Software Timing: The rate is determined by the software and operating system. It is generally less accurate than hardware timing.

import nidaqmx
from nidaqmx.constants import AcquisitionType, READ_ALL_AVAILABLE

# Example of configuring hardware timing for a finite acquisition
with nidaqmx.Task() as task:
    task.ai_channels.add_ai_voltage_chan("Dev1/ai0")
    task.timing.cfg_samp_clk_timing(1000.0, sample_mode=AcquisitionType.FINITE, samps_per_chan=10)
    data = task.read(READ_ALL_AVAILABLE)

Install the standard nidaqmx package using pip. Note that running the package requires the NI-DAQmx driver to be installed on your system.

python -m pip install nidaqmx

Technical Data Management Streaming (TDMS) is a binary format for high-speed data logging. You can configure a task to stream data directly from the device buffer to the hard disk using configure_logging.

import nidaqmx
from nidaqmx.constants import AcquisitionType, LoggingMode, LoggingOperation, READ_ALL_AVAILABLE

with nidaqmx.Task() as task:
    task.ai_channels.add_ai_voltage_chan("Dev1/ai0")
    task.timing.cfg_samp_clk_timing(1000.0, sample_mode=AcquisitionType.FINITE, samps_per_chan=10)
    # Configure logging to a file
    task.in_stream.configure_logging(
        "TestData.tdms", 
        LoggingMode.LOG_AND_READ, 
        operation=LoggingOperation.CREATE_OR_REPLACE
    )
    data = task.read(READ_ALL_AVAILABLE)

The nidaqmx module includes a CLI command to automate the installation of the NI-DAQmx driver.

• Windows: Downloads and launches an online streaming installer from ni.com.
• Linux: Downloads the repository registration package for your distribution and installs it via your package manager.

python -m nidaqmx installdriver

To use nidaqmx with gRPC, install it with the grpc extra to include the required dependencies.

python -m pip install nidaqmx[grpc]