Debugging printing GRC - E110


I’ve a kind of basic question, but it has taken me a lot of time to
out. I made a signal processing chain of blocks (very simple in facts,
generate PSDU then send as a message downstream, manipulate the content
count the number of message that I’ve received). In order to debug my
blocks, in .cc files I’m using:

std::cout << std::endl << “running routine in BLOCK 1” << std::endl;

I populated my blocks with several messages, so I know what is going on
every time. I can see the messages printed out in GRC (using NO Gui
options). All the messages are correctly displayed, so I assumed that is
running OK. Then, I generated the file and put into the
When I run the, I see only this:

linux; GNU C++ version 4.5.3 20110311 (prerelease); Boost_104500;

Press Enter to quit: gr_block_executor: source <gr_block uhd st2 (2)>
produced no output. We’re marking it DONE.

It only shows the starting of the blocks and when it finishes, but it is
not showing my debug messages.* If I’m using std::cout into C++ for
block, should I see those messages in my E110?.*

Thanks a lot for your help,


On 10/22/2012 09:28 PM, Jose T. Diaz wrote:

I populated my blocks with several messages, so I know what is going on
produced no output. We’re marking it DONE.
I think its just a gnuradio version thing. We just recently made a
change to work functions can return without producing samples. I
mentioned this in the other thread.

Seriously though, if you are just doing message passing stuff, and you
are having issue w/ returning from work. Dont return. Just dont do it.
Either block on pop_msg_queue or spin on whatever your function needs to

The message passing is completely implemented outside of the scheduler.
So this is one of the downsides for now. In future endeavors, this will
be smart and integrated, and doing things like return from work will not
be an issue.


Hi Josh,

Thanks for your answer. Here my comments:

  1. I fixed the problem just not using any return in the work function.
    Also, in BLOCK 1 work function (), I added a usleep(20), this gives
    enough time to the other blocks to run their work functions.

  2. So, does it mean that I should install the latest version of GNU
    radio? If yes, where is the link of the latest version?.

Thanks again and your comments are very useful!,


Hi Josh,

This is kind of silly question. Now I have this version of GNU radio in

gnuradio-config-info -v

If I build the newest version, how can I know which version is available



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