[USRP-users] Persistent red LINK LED, streaming samples valued zero

Hai Nguyen hai.n.nguyen204 at gmail.com
Tue Jul 21 11:00:38 EDT 2020

Hi Marcus,

- Are you creating a multi_usrp object for each USRP, or are you creating a
single multi_usrp object with multiple streamers coming out of that object?
I'm having a multi_usrp object for each USRP, with a streamer for each

- Is this on Linux or Windows?
This is on Linux (Ubuntu 16.04)

- Are the USRPs on the same, or different, network interfaces?
They are on different network interfaces with 10GigE connection for each.


On Tue, Jul 21, 2020 at 2:20 AM Hai Nguyen <hai.n.nguyen204 at gmail.com>

> Hi Marcus,
> So with new UHD version, the LED behavior disappeared, but now the USRPs
> cannot stream at all (0 samples received from streamer). I figured out that
> this happens when I tried to create multiple threads for multiple
> streamers, one streamer for one USRP. (I'm having 2 USRPs streaming 2 RX
> channels simultaneously). I had to work around this by creating just one
> extra thread for a USRP, while making the other USRP stream in the current
> main thread. Another possible way would be using a single streamer...
> I'm kinda confused (and curious!) why it is not possible to spawn multiple
> threads for multiple streamers. This was not happening with B210s, but just
> when I started to work with the X310s. I will be appreciate for further
> info about this behavior.
> -Hai
> On Mon, Jul 20, 2020 at 12:32 PM Hai Nguyen <hai.n.nguyen204 at gmail.com>
> wrote:
>> Hello,
>> - Are you getting any under-run indications?
>> There is no under-run indication.
>> - What sample rate are you using?
>> I tried with different values ranging from 1 Msamps to 100 Msamps and the
>> behaviors are the same.
>> - Do you see this at the same sample rate with an example application
>> like
>> "rx_samples_to_file".   Are you using standard FPGA firmware or do
>>    you have your own modules in the FPGA?
>> No, I don't see this with rx_samples_to_file (with that example, orange
>> LINK LED appeared). I am using a standard FPGA image.
>> - What version of UHD are you using?
>> I'm using UHD 3.9.7 (LTS)
>> Best,
>> Hai
>> On Mon, Jul 20, 2020 at 1:52 AM Hai Nguyen <hai.n.nguyen204 at gmail.com>
>> wrote:
>>> Hello,
>>> I'm having an error where received samples from RX chains of a X310
>>> (after calling recv from the streamer) have values of 0 (both I and Q), and
>>> those values don't change over time. One abnormal thing is that the LINK
>>> LED in the front panel is persistently red during streaming. I noticed that
>>> when streaming samples is ok this LED is normally persistently orange
>>> instead.
>>> Do you have any ideas what would be the cause of this?
>>> Thank you and best regards,
>>> Hai
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20200721/c941db7e/attachment.html>

More information about the USRP-users mailing list