XNET Signal Session Displays Data as Zeroes

Updated Aug 8, 2018

Reported In

Hardware

  • PXI-8513

Software

  • LabVIEW

Driver

  • NI-XNET

Issue Details

I am using an XNET Signal In Single-Point session with a custom database file to read signals from my CAN bus, but my data array is shown as all zeroes. I receive no XNET errors. Why is this happening?

Solution

There could be a variety of reasons you aren't acquiring data. Follow these steps to troubleshoot them:
  • If your device has 2 or more ports, run a loopback test to ensure that the device is not broken
  • Run the XNET Bus Monitor (while your bus is transmitting data) to see if any data shows up
    • If no data shows up, ensure that:
      • The baud rate of the database is set properly. You can use the XNET Database Editor to adjust this value.
      • There is proper termination on your CAN bus. If you don't have access to a terminated cable or physical termination resistors, your device may support software termination. To enable this: Place down XNET Session Property Node >> Interface >> CAN >> Termination >> Right-Click the input terminal >> Create >> Constant >> Left-Click the 'Off' constant >> 'On' as shown below:
  • Once data shows up in the Bus Monitor, that means that we are at least getting proper data. Now, test if your data displays properly by running the CAN Signal Input Single Point example VI (Help >> Find Examples >> Browse >> Hardware Input and Output >> CAN >> NI-XNET >> Intro to Sessions >> Signal Sessions >> 'CAN Signal Input Single Point')
    • Make sure to select a signal that did not display zeroes as bytes in the Data field of the Bus Monitor. For instance, the signal with ID 1011 from below would be a good choice because the Data payload contains data:
      • You can find this signal in your database through the XNET Database Editor and looking for a matching Arbitration ID field
    • If data still does not show up, there is an issue between your database and your ECU. Either edit your database to accommodate the right signal, or swap either the database or ECU to make sure they're compatible
 
 

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