Short answer: You cannot open a new USRP instance to reconfigure an
already-running USRP instance. You must reconfigure the existing instance.

The best advice I can give is that only one flowgraph can be operational per
USRP device. In your setup, USRP#1 will run a single flowgraph with a source
and/or sink, USRP#2 will run a single flowgraph with a source and/or sink,
and USRP#3 will run a single flowgraph with a source and/or sink. If you
wish to change the parameters of USRP#2 while it is running, rather than try
to open a new USRP device in your benchmark_rxr.py flowgraph, use any of the
standard interprocess communication methods to talk to your already-running
USRP#2 script and reconfigure it as necessary.

--n

On Wed, Sep 7, 2011 at 9:31 AM, Lebowski80 <[email protected]> wrote:

>
> Hello Nick,
>
> What do you mean? Actually I'm running RX and TX in two different
> flowgraphs
> on USRP1, the first one in usrp_spectrum_sense.py to look for a free
> channel
> (so the RX). In this script I also run benchmark_tx.py by the command p =
> Popen('python benchmark_tx.py', shell =  True), then my second flowgrapgh
> (the TX).
>
> My problem is that on USRP2 I want to reconfigure the RX channel by python
> (RX channel = 2484 MHz in the script benchmark_rx.py and RX channel =
> channel received by USRP1 in the script benchamrk_rxr.py run by
> benchmark_rx.py with the command p = Popen('python benchmark_rxr.py', shell
> =  True)).
>
> So I'm wondering if there exists the possibility to reconfigure the
> parameters of a script in the same USRP (i.e. RX frequency channel) while
> it
> is running and if this is not possible what do people mean with "USRP
> reconfigurability?"
>
> I really need an answer to understand the potentiality of my hardware,
> thanks a lot!
>
> Regards
>
>
>
> Nick Foster-4 wrote:
> >
> > On Wed, Sep 7, 2011 at 3:27 AM, Lebowski80 <[email protected]>
> > wrote:
> >
> >>
> >> Hello everyone,
> >>
> >> Before to explain my problem I give some technical information about my
> >> hardaware. I'm using USRPs v1 and the boards integrated are XCVR2450
> >> Transceivers.
> >>
> >> I'm using the script usrp_spectrum_sense.py in a USRP (called USRP1) to
> >> make
> >> sensing in the ISM band, after a few seconds it sends to another USRP
> >> (Called USRP2) a free sensed channel on the central frequency 2484 MHz.
> >> USRP2 listens to the channel 2484 MHz through the script benchmark_rx.py
> >> and
> >> it can properly receive the free ISM channel sent by USRP1. Then, I want
> >> to
> >> use the USRP2 to receive data from another USRP (called USRP3) that uses
> >> the
> >> script benchmark_tx.py.
> >>
> >> In the script benchmark_rx.py (used by USRP2) that listens to channel
> >> 2484
> >> MHz I want to run another script that I called benchmark_rxr.py that
> >> waits
> >> for data sent by USRP3 to be received in the free ISM channel sent by
> >> USRP1.
> >>
> >> Relevant line of the code in the script benchmark_rx.py is attached
> >> below:
> >>
> >> p = Popen('python benchmark_rxr.py', shell =  True)
> >>
> >> While this is the error that I get:
> >>
> >> usrp_open_interface:usb_claim_interface: failed interface 2
> >> could not claim interface 2: Device or resource busy
> >> usrp_basic_rx: can't open rx interface
> >> Traceback (most recent call last):
> >>  File "benchmark_rxr.py", line 153, in <module>
> >>    main()
> >>  File "benchmark_rxr.py", line 138, in main
> >>    tb = my_top_block(demods[options.modulation],
> >> mods[options.modulation],
> >> rx_callback, options)
> >>  File "benchmark_rxr.py", line 46, in __init__
> >>    self.rxpath = usrp_receive_path.usrp_receive_path(demodulator,
> >> rx_callback, options)
> >>  File
> "/opt/gnuradio/gnuradio-examples/python/usrp/usrp_receive_path.py",
> >> line 65, in __init__
> >>    self._setup_usrp_source(options)
> >>  File
> "/opt/gnuradio/gnuradio-examples/python/usrp/usrp_receive_path.py",
> >> line 78, in _setup_usrp_source
> >>    self.u = usrp_options.create_usrp_source(options)
> >>  File "/usr/local/lib/python2.6/dist-packages/gnuradio/usrp_options.py",
> >> line 88, in create_usrp_source
> >>    gain=options.rx_gain,
> >>  File
> >>
> >>
> "/usr/local/lib/python2.6/dist-packages/gnuradio/blks2impl/generic_usrp.py",
> >> line 138, in __init__
> >>    _generic_usrp_base.__init__(self, **kwargs)
> >>  File
> >>
> >>
> "/usr/local/lib/python2.6/dist-packages/gnuradio/blks2impl/generic_usrp.py",
> >> line 63, in __init__
> >>    except: raise Exception, 'Failed to automatically setup a usrp
> >> device.'
> >> Exception: Failed to automatically setup a usrp device.
> >>
> >> I read different post with this problem such as "Full duplex and half
> >> duplex
> >> does not work" and "help: cannot send after transport endpoint shutdown"
> >> but
> >> I could not solve the problem yet. I need to close the reception in 2484
> >> MHz
> >> channel for a new reception in another channel in USRP2. The only way to
> >> do
> >> that seems to close the port manually (i.e. pressing ctrl+c) but I want
> >> to
> >> do that by code. I tried different things before the line "p =
> >> Popen('python
> >> benchmark_rxr.py', shell =  True)" such as "id_process = os.getpid()"
> and
> >> "os.killpg(id_process, 2)", or by "tb.lock()" and "tb.unlock" and so on,
> >> but
> >> nothing helped me, I keep obtaining the same error. I don't know what to
> >> do
> >> else, can I change by code reception frequency in USRP2? Any advice will
> >> be
> >> welcome, thanks a lot!
> >>
> >
> > You need to run both RX and TX in the same flowgraph. You can't open them
> > in
> > separate flowgraphs.
> >
> > --n
> >
> >
> >
> >>
> >> Regards
> >>
> >>
> >> --
> >> View this message in context:
> >>
> http://old.nabble.com/How-to-reconfigure-automatically-the-channel-used-to-received-data-in-USRPs-tp32414957p32414957.html
> >> Sent from the GnuRadio mailing list archive at Nabble.com.
> >>
> >>
> >> _______________________________________________
> >> Discuss-gnuradio mailing list
> >> [email protected]
> >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>
> >
> > _______________________________________________
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> >
> >
>
> --
> View this message in context:
> http://old.nabble.com/How-to-reconfigure-automatically-the-channel-used-to-received-data-in-USRPs-tp32414957p32417577.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
>
>
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