Reconfiguring Flowgraphs

GNU Radio
1

Hi all:
Thank you in advance.I want to ask some questions about the
“Reconfiguring Flowgraphs”.
My flowgraphs:
source—>block A(just one
block)—>sink
And I want to run the flowgraphs for 30 seconds,and then run the other
flowgraphs:
source—>block B(just one
block)—>sink
And I have read the API,and then I write something like this:

def main():
tb=my_top_block()
tb.start()
time.sleep(30)

#stop flowgraph
tb.lock()
tb.disconnect((tb.uhd_usrp_source_0,0),(tb.rx_0,0))

#start flowgraph
tb.connect((tb.uhd_usrp_source_0,0),(tb.rx_1,0))
tb.connect((tb.rx_1,0),tb.snk)
            #  blockA:(tb.rx_0,0)    blockB:(tb.rx_1,0)
            tb.unlock()

tb.wait()

But it go error: RuntimeError: delay(4): insufficient connected input
ports (1 needed, 0 connected)
Can someone help me?Thank you.
Best regards,
xd

2

I forget to say:the “sink” also different with each other.Namely:
source—>block A(just one block)—>sink1
source—>block B(just one block)—>sink2
Can someone help me?Thanks.

At 2014-07-21 06:50:10, “xianda” [email protected] wrote:

Hi all:
Thank you in advance.I want to ask some questions about the
“Reconfiguring Flowgraphs”.
My flowgraphs:
source—>block A(just one
block)—>sink
And I want to run the flowgraphs for 30 seconds,and then run the other
flowgraphs:
source—>block B(just one
block)—>sink
And I have read the API,and then I write something like this:

def main():
tb=my_top_block()
tb.start()
time.sleep(30)

#stop flowgraph
tb.lock()
tb.disconnect((tb.uhd_usrp_source_0,0),(tb.rx_0,0))

#start flowgraph
tb.connect((tb.uhd_usrp_source_0,0),(tb.rx_1,0))
tb.connect((tb.rx_1,0),tb.snk)
            #  blockA:(tb.rx_0,0)    blockB:(tb.rx_1,0)
            tb.unlock()

tb.wait()

But it go error: RuntimeError: delay(4): insufficient connected input
ports (1 needed, 0 connected)
Can someone help me?Thank you.
Best regards,
xd

3

unless you also disconnect block A and sink1, GNU Radio will continue to
assume that block A should produce output for sink1, and it can’t do
that without input.

Greetings,
Marcus

4

Hi Xianda,

as usual, saying “doesn’t work”, “can’t run”, “behaves wrong” really
gives no clue what’s wrong.
Please follow
http://gnuradio.org/redmine/projects/gnuradio/wiki/ReportingErrors ,
especially “How do I ask?”.

Greetings,
Marcus

5

Hi xianda,

tb.wait() does exactly what you said it does: Wait for the flow graph to
complete.A flowgraph will run until one of the blocks in that flowgraph
signal that they’re done, or you call tb.stop().
If you don’t have such a block, your tb will run forever, and wait()
will never return.

Greetings,
Marcus

6

Hi Marcus:
Thank you for your reply.Sorry for that if you can’t
understand.I will try my best to explain my question.

def main():
tb=my_top_block()
tb.start()
time.sleep(30)

#stop flowgraph
tb.lock()
tb.disconnect((tb.uhd_usrp_source_0,0),(tb.rx_0,0))
            tb.disconnct((tb.rx_0,0),tb.snk1)
             #start flowgraph
 tb.connect((tb.uhd_usrp_source_0,0),(tb.rx_1,0))
 tb.connect((tb.rx_1,0),tb.snk)
             #  blockA:(tb.rx_0,0)    blockB:(tb.rx_1,0)
             tb.unlock()
  tb.wait()
             print "start"

I want to disconnct flow graph, and then to start a new connect.My code
hang in tb.wait(),it can’t go on.I add print “start” and it can’t
display “start”.Sorry for my poor english if you can’t understand.
Thank you so much.
Best regards,
xd

7

Xianda,
my advice: Please try to draw a complete picture of what you are doing.
What are your sources, blocks you interchange, your sinks, what do you
do to make your flowgraph stop (under which circumstances)? I really
can’t read your mind; all I know about your flow graph is what you tell
me, which is that you have 1 source, and two in-and-output blocks and
two sinks, and that you first connect src - blk1 - sink1 and then src -
blk2 - sink2.

You omitted that it is a USRP source until you send an excerpt of your
code, you omit what kind of blocks blk{1,2} and what kind of sinks
sink{1,2} are. You don’t tell me in what relationship your “new”
flowgraph stands to your reconfigured one etc.

It’s like you expect me to guess what you are doing in my own time to
try to help you, just to save you from revealing what you are doing.
This won’t work.
Please explain, in whole, what you’re trying to do, what you have tried
to verify that it goes wrong, which problems you encountered and so on,
and we, as a list, might be able to figure out what’s going on.

Greetings,
Marcus

8

Hi Marcus:
Thank you so much.Do you indicate my new flowgraph had
run?I have add a file sink,but it is null.And I think it don’t run.I
don’t know why.Can you give me some advices?Thank you so much.
Best regards,
xd

9

Hi Marcus:
Thank you so much for your kindly reply.I have
attached my code.I want to run the flowgraph 1 at first,and then I
disconnct it.Then I want to run the flowgraph 2.
Flowgraph 1:
uhd_usrp_source---->>>ofdm_rx_0---->>>file sink

                Flowgraph 2:
                uhd_usrp_source---->>>ofdm_rx_1---->>>blocks_vector_to_stream---->>>blks2_tcp_sink

Note:
ofdm_rx is a block in
gnuradio/gr-digital/python/digital/ofdm_txrx.py.I make some changes on
ofdm_rx.And I get two new block:ofdm_rx_0 and ofdm_rx_1.I have tested
flowgraph 1 and flowgraph 2 respectively.And they all run
successfully.And now I just want to run flowgraph 1 in 30 seconds and
then disconnct flowgraph 1.Then run flowgraph 2 forever.But now the
flowgraph 2 don’t receive samples.And in the ofdm_rx_1 I add some file
sink.These file sink display null.When I have tested flowgraph 1 and
flowgraph 2 respectively,these file sink all have samples.So I think
maybe encounter some errors when I reconfiguring flowgraphs.Thank you so
much.So kindly of you.Thanks.
Best regards,
xd

10

so if you replace lines 70-79 and replace them with tb.stop(), you get
bytes in your file? How many? Is it much more than 52*8? Do you actually
guarantee that there should be output of ofdm_rx_0 or does this happen
coincidentially?

Something as complex as an OFDM receiver really shouldn’t be used as a
test for stream reconfiguration, because you’re receiving live signals
and there’s millions of things that might go wrong; have you tried with
a simpler block, e.g. stream_to_vector instead of ofdm_rx/ofdm_rx1? Have
you intentionally used
“from ofdm_null_txrx import ofdm_rx”? I don’t know ofdm_null_txrx, so
this might be to blame; the name sure suggests that it might not produce
output, and the parameters suggest you send data somewhere (not to the
output of that block).

Greetings,
Marcus