[USRP-users] subdev vs. channels

Michael West michael.west at ettus.com
Mon Jul 13 16:26:44 EDT 2015

Hi Maurizio,

The subdevice specification is not necessary to supply in most cases.  It
allows users to more specifically map the RF front ends to channels.  By
default, the front ends are enumerated where channel 0 is the first front
end on the first device and channel N is the last front end on the last
device.  The order of the device adresses during the multi_usrp object
creation defines the order of enumeration of the devices.

For your use case, you do not need to provide a subdev spec.  You only need
to provide the correct ordering for the device addresses and indicate the
channel(s) you intend to use.


P.S.  The documentation for all products can be found at

On Mon, Jul 13, 2015 at 1:14 AM, Crozzoli Maurizio via USRP-users <
usrp-users at lists.ettus.com> wrote:

>  With reference to the sample code “rx_multi_samples.cpp” provided in the
> Ettus code site, could someone please explain (or give some reference to
> some documentation) the difference between the “subdev” specification and
> the “channels”?
> With reference to the boards B220 and E310 (we already have the first one,
> we are just buying the second one), we would like to be able to select more
> than one RX chain (from 2 to 4) but it is not clear if that situation is to
> be handled by “subdevices” and/or “channels”. Looking at the code it seems
> that all the “trick” is done by managing the “channels” and the
> “subdevices” is almost useless… For sure I am wrong, that is why I am
> asking for help here…
> TIA!
> BR,
> Maurizio.
> PS Why just a few week ago http://code.ettus.com/ could be freely
> accessed and now it requires username/password? And how to get them?
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