Automotive and Embedded Networks
USB XNet Device Alias Missing on RT Target
Solved!
TLDR: Is the USB 8502 supposed to work on Linux RT targets? The one I have to test with is only showing RAW device in MAX.
EDIT: Oh no I think I found my answer. Why can't the USB devices be supported on Linux RT? And why isn't this listed in the data sheet? I had to go searching for various compatibilities tables and release notes. And the only place I found the answer was on a topic about Linux Desktop development which I am not trying to do at all, and having a line under the Additional Information.
Is there a reason that a USB-8502 XNet device might only show up as a raw device, and not have the alias information populated for a particular target? I ask because I'm doing some preliminary testing and I noticed that one of my targets doesn't enumerate the USB device in MAX. Here is MAX on my local host machine with the USB device plugged in which shows CAN11 and CAN 12:
And here is MAX looking at the remote Linux RT device with it plugged in there.
I wasn't sure if the best place to ask about it was here or over on the Linux RT subforum. Are these USB XNet devices supported on Linux RT? It seems like they are but I'm at home at the moment and don't have access to another variant to test on. Thanks.
Bump.
"I think I found my answer. Why can't the USB devices be supported on Linux RT?
And why isn't this listed in the data sheet? I had to go searching for various compatibilities tables and release notes. And the only place I found the answer was on a topic about Linux Desktop development which I am not trying to do at all, and having a line under the Additional Information."
Having now passed the 4 month anniversary of talking to myself here, having sent out PMs, and bumping this thread multiple times, I start to guess reasons why no one from NI has replied. I have several theories but they can all be eliminated if just one employee of NI can come here and answer my questions.
- Can I run the 8502 on a Linux RT system?
- If not, why not?
- Also If not, then can the documentation be made more clear to illustrate this limitation?
As a developer the first thing I might look at is the support for the driver level software on the platform I want. If I go to the readme on the XNet driver here. I see that Linux RT is a supported platform for XNet. On that same page I see the 8502 as supported hardware. If I look at the known issues page there is something about the 850x device on Phar Lap but RT Linux isn't mentioned. The next place I might look is the 850x device page itself. Here is the 8502 where it doesn't mention supported operating systems or environments.
So I have a driver that is supported on my target, I have no known issues on my target, and the hardware doesn't specify any target limitations. This lead me to believe it would be supported because other XNet devices that are supported on my target also don't explicitly state what will and won't work.
As for my setup. While my screenshot was of a PXI chassis I also have a NI-9136 which is an RT cDAQ device and that wasn't listed on the PXI support page because it isn't a PXI. That page you linked to also is pretty hard to use with a drop down of many devices, but no scroll bar. Beyond that though once I pick a device I'm unsure how this helps. I picked the PXIe-8861 which is an x86 based Linux RT system, and all it tells me is that the PXI Platform Services 19.0 is needed. Okay but where does this say what hardware is and isn't supported? How is that page supposed to tell me that the 8502 isn't supported? I went to the PXI Platform Services manual and it doesn't list supported hardware.
My use case is really just we have some Linux RT targets, and we'd like to support more XNet ports if needed. PXI and C-Series slots are often at a premium, and if I can design a system to use a USB XNet device and free up a slot then that gives me extra flexibility.
