How to detect a disconnected LIN Device

Updated Jun 26, 2020

Reported In

Driver

  • NI-XNET

Issue Details

How can I detect that I have lost the connection to my device. When the session starts without the device it only shows zeros but if I disconnect the device during the session I get old values. 

Solution

To detect that a device is no longer on the bus you can use a XNET special frame called LIN No Response Frame. This frame is generate when a header with no response is detected on the LIN bus. This in essence is when a request is sent to a device to complete the frame with a payload but due to the device not being present it's returned empty. To be able to log this special frame, you must use a XNET session node to enable it. 

Additional Information

A simple way to implement this is basing your code on the LabVIEW example called LIN Raw Frame Input Stream that you can find by opening the Example Finder > Hardware Input and Output > LIN > Intro to Sessions > Frame Sessions.

You can save a new version of this example and expand the XNET Session property node that is include and select the property No Response to Input Stream Frame?, you will find it by right clicking the new property and going to Select Propery > Interface > LIN.