Example Code

Channel Expansion with External Reference Clock

Products and Environment

This section reflects the products and operating system used to create the example.

To download NI software, including the products shown below, visit ni.com/downloads.


  • Data Acquisition (DAQ)


  • LabVIEW


  • NI DAQmx

Code and Documents


Using multiple S-series or X-series cards, I want to simultaneously acquire data. However, I also need to use an external clock source. This example shows there is a way to simultaneously acquire the data on multiple cards while using an external clock source.

By wiring through the PXI_Trig lines, you are able to use an external clock source as your sample clock. Channel expansion takes care of simultaneously sampling on multiple devices in the background. This code shows a typical setup that you could use, although in this example, the external clock is provided to the PXI_Trig line from a counter

Steps to implement or execute code
To implement this example:

  1. Utilize the Multiple Multifunction DAQ Devices with PXI chassis
  2. Change the inputs for the system
  3. Run the VI
  4. (Optional) Turn on the Highlight Execution to see the flow of the VI

To execute this example:

  1. Install the required software.
  2. Connect the PXI Chassis that supports the multipe DAQ Devices and Counter features
  3. Confirm the connection with the MAX with TestPanel
  4. Open the VI and refer the Implement Steps

LabVIEW 2012 or compatible
NI-DAQmx 9.0 or compatible

PXI Chassis with multipe DAQ Devices and Counter Module



**This document has been updated to meet the current required format for the NI Code Exchange.**

Matt P.
Applications Engineer
National Instruments

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.