LabVIEW

LVRT uses randomly 5 to 90% of the CPU load

We have a problem with our sbrio-9651 som board.

We use it as a Ethercat master, which requires the scan engine to operate.

On startup we load the FPGA (with second ethernet port) and search for Ethercat slaves. When 1 or more is connected and the scan engine is set to active mode with loop cycle on 1 ms, the cpu load has sometimes around 5% load on both cores, and sometimes 1 core has around 70% load.

For this we don't need to actually read out data from the Ethercat in our user code.

The only running user code is shown in the attachment.

This test is done with LV2014SP1

We also tried LV2015 but this is not usable because when the second ethernet port is set to be used for ethercat the port disappears from MAX. When we look in the Linux console we see also a kernel panic when we try to use this port for ethercat.

We made a workaround for the load issue, which is reboot untill the cpu load is low. (3 times max), but we really want to sort out where this issue comes from and why we see this huge difference in CPU load.

We want to use more slaves but with this huge load differences it's not safe for stable use.

We have a sample project based on an example with very little user code and even an image for the whole SOM with all software, available on request.

For this issue we thought it would be faster to contact NI directly with a service request, but this takes already more than a month and we still get questions like "We would also like to ask why you're using the scan engine functions in your code"

Any help is appreciated. Thanks.