Re: [Discuss-gnuradio] Problem w. block Message Source

[Jose Rodriguez]

On Tue, Jan 28, 2014 at 12:05 PM, Tom Rondeau <tom@trondeau.com> wrote:

On Tue, Jan 28, 2014 at 11:10 AM, Jose Rodriguez
<address@hidden> wrote:
>
> Hi,
>
> I am a beginner at Gnuradio and I am working on writing some simple graphs.
> I am having a problem w. the block "Message Source".
>
> I got the block "Message Strobe" connected to "Message Source" (the goal is
> to extract the data bytes and feed them to a "Packet Encoder" block).
>
> The graph builds OK but when run I get:
>
> Using Volk machine: avx_64_mmx_orc
> Traceback (most recent call last):
>   File "/home/joser/Desktop/xx/top_block.py", line 120, in <module>
>     tb = top_block()
>   File "/home/joser/Desktop/xx/top_block.py", line 72, in __init__
>     self.blocks_message_source_0 = blocks.message_source(gr.sizeof_char*1,
> blocks_message_source_0_msgq_in)
> NameError: global name 'blocks_message_source_0_msgq_in' is not defined
>
>>>> Done
>
> Any idea what the problem could be?

It's certainly not obvious from that error message, but what's going
on is that you are using the two different message systems in GNU
Radio. The message_source is designed to work with a special msg_queue
concept while the message strobe block is part of the newer
asynchronous message passing architecture. Notice how they are
different colors and so don't belong together.

OK, yes they are different colors (light grey vs. dark grey), my mistake. Quick question, what block can/should be used to extract the data in the message generated by Message Strobe?

We should add some language to the message passing page in the manual
to better explain this distinction.

> I checked: http://gnuradio.org/doc/doxygen/page_msg_passing.html and at the
> bottom is says to look at the examples in gr-blocks/examples/msg_passing but
> I get missing link errors when I load these files in my setup.
>
> My setup is gnuradio 3.7.2.1 running in Ubuntu 12.04.4 LTS.
>
> thanks for any help,
>
> Jose Rodriguez
> address@hidden

What exactly do you mean by link errors? Are you talking about missing
blocks in the GRC graph or when you run it, you are getting linking
errors in the library? Neither of which should be happening on that
release.

Tom

By "missing link errors" I meant that when the grc file is loaded, some blocks are not connected. For example, when I load gr-blocks/examples/msg_passing/strobe.grc in the screen there are two Message Strobe blocks whose output are not connected. Also I get the following output:

Loading: "/home/joser/gnuradio/gnuradio/gr-blocks/examples/msg_passing/strobe.grc"
>>> Error: Connection between blocks_message_strobe_0(0) and blocks_message_debug_0(0) could not be made.
    source key "0" not in source block keys
>>> Error: Connection between blocks_message_strobe_0_0(0) and blocks_pdu_to_tagged_stream_0(0) could not be made.
    source key "0" not in source block keys
>>> Error: Connection between blocks_tagged_stream_to_pdu_0(0) and blocks_message_debug_0(2) could not be made.
    source key "0" not in source block keys
>>> Done

It could be my setup (I have reloaded Gnuradio several times, I have found that there are many example grc files out there which is great, but often they are based on 3.6. I tried to have both releases 3.6 and 3.7 installed with no success). Anyway, thanks for the quick response.

Jose

address@hidden