Use NI 9469 to Synchronize Two Chassis

Updated Nov 2, 2021

Environment

Hardware

  • NI-9469
  • cDAQ-9178
  • NI-9229

Software

  • LabVIEW
  • Measurement & Automation Explorer (MAX)

I have two CDAQ-9178 chassis and two NI 9229. What do I need to do to synchronize these two chassis?

  1. Each chassis must have one NI 9469 to be installed, so two NI 9469 are required in this case.
  2. Check the module datasheet to ensure that these modules allows synchronization.
    • Module which accept external master time base is one example of the criteria.
  3. Plug in power of each chassis CDAQ 9178.
  4. Use USB cables to connect two CDAQ 9178 to the same host computer.
  5. Install one NI 9469 and NI 9229 on each CDAQ 9178.
  6. According to NI 9469 Getting Started Guide, CAT 5e (Shielded Twisted Pair) wire should be used to connect two NI 9469.
    • Some CAT 5e wire engrave words "CATEGORY 5E PATCH CABLE"
  7. Select any topology based on application and timing requirements. In this example, star topology is selected because it can reduce skew and delay due to shorter cable.
  8. Refer to Synchronization Explained , design Labview VI programming code by focus criteria below:
    • Master & slave - Slave device should start task before master device.
    • Trigger - It's recommended to share same trigger between 2 chassis. 
    • Share same time base - NI 9469 can provide a reference clock at 13.1072 MHz or 12.8 MHz.
  9. Refer Example section for more information of Labview VI synchronization code.

Verify two chassis whether are synchronized or not by refer t0 (time acquired of first data) in timestamp.
If both devices' task t0 are same, it means both chassis are synchronized. 
  1. In DAQmx Read.vi, select Analog >> Multiple Channels >> Multiple Samples >> 1D Waveform (Duration). 
    • 2.JPG
  2. Right click at output data >> Create indicator.
    • 3.JPG
  3. Compare t0 for both devices.
    • 4.jpg

The KB Synchronization Options for Multiple cDAQ Chassis With the NI 9469 got provide Labview synchronization example code.
  1. Delta Sigma Modules.vi is selected because NI 9229 equip with Delta-Sigma ADC.
  2. Delete extra components and left two virtual channel for two CDAQ-9178.
    • Capture.JPG
  3. Select and configure settings before run VI.
    • 9.JPG