Re: Confusion about 'ports'

[Marcus D. Leech]

On 2022-03-16 15:41, Chad Spooner wrote:

Some information I should have included the first time:

OS: Ubuntu 20.04.3

gnuradio: 3.9.4.0

UHD: 3.15.0.0-2build5

Maybe somebody has a simple shareable flowgraph running under these conditions and that has two USRP Source blocks and one USRP Sink block?

Thanks,

C

On 3/14/22 4:02 PM, Chad Spooner wrote:

All:

I've got a simple flowgraph with two USRP Source blocks and a single USRP Sink block:

This flowgraph is running on an x310. The upper Source block is supposed to stream data coming from another SDR, and the lower Source block is supposed to stream data from an antenna. Then I add these together and output the sum with the Sink block.

When I run it I get this error:

gr::log :ERROR: thread_body_wrapper - ERROR thread[thread-per-block[2]: <block usrp_source
(1)>]: RuntimeError: On node 0/DDC_0, output port 0 is already connected.

If I disable one of the Source blocks, things work as expected, so it is the presence of both that is the problem.

I can't tell from the documentation what a 'port' is, exactly. And there isn't any error message in the companion itself, so I guess it thinks this is OK.

Can somebody please point me to a clear discussion of how 'ports' enter here or please suggest a way to modify the flowgraph?

Thanks,

C

    Chad:
    
    I put what I thought was a reasonable effort into my previous reply
    on this subject, which you either didn't see, or didn't understand.
    
    You *CANNOT* "splilt" a USRP hardware device across multiple
    source/sink blocks.  If your device has multiple channels that you
    wish to
      take advantage of, you must have that device in a single block,
    and use a multi-channel configuration to produce multiple outputs.
    
    You haven't yet responded to my request for a notion of the hardware
    configuration of your USRP devices--one I think is an X310--but you
    hadn't
      mentioned what the RF daughtercard configuration is, so none of us
    here can give really-detailed advice.