Re: [Discuss-gnuradio] UHD and gr_block_executor error: "source <gr_block gr uhd usrp source (1)> produced no output. We're marking it DONE."

[Ulrika Uppman]

Hello,
We have been seeing a similar problem when we tried to change a top block by 
stopping it and then creating a new top block.

First it looked like the problem was related to the synchronization of uhd 
sources, see 
http://lists.gnu.org/archive/html/discuss-gnuradio/2011-05/msg00441.html (The 
start of the discussion is here: 
http://lists.gnu.org/archive/html/discuss-gnuradio/2011-04/msg00537.html)

Later we found that the problem still occurred after the fix with the timeout. 
We noticed that when looking at the clock signals on an oscilloscope, the 
sources didn't resynchronize properly. When this happened, the error you see 
also appeared. We fixed this by setting the top block to 0 before creating a 
new top block.
for i in range(4):
     tb = 0
     tb = top_block()
     tb.start()

Maybe something isn't reset properly or maybe this is some sort of 
garbage-collection related problem? Any other ideas?

/Ulrika

> -----Original Message-----
> From: address@hidden 
> [mailto:address@hidden
>  On Behalf Of Christopher Dean
> Sent: Tuesday, August 02, 2011 8:55 PM
> To: address@hidden
> Subject: [Discuss-gnuradio] UHD and gr_block_executor error: 
> "source <gr_block gr uhd usrp source (1)> produced no output. 
> We're marking it DONE."
> 
> Hi All,
> 
> I'm working on a program that allows two E100's to 
> communicate over radio frequencies.  This program runs well 
> on a pair of N210s, but on the On the receiving end, the 
> program has two principle flow graphs that both connect to 
> the uhd usrp source.  The first one used (A) is used only at 
> the beginning of the program; afterwards, the second flow graph
> (B) is used.  Upon running the program, I'm getting the 
> following error
> messages:
> 
>      UHD source block got error code 0x9
>      gr_block_executor: source <gr_block gr uhd usrp source 
> (1)> produced no output.  We're marking it DONE.
> 
> and, much more frequently,
> 
>      UHD source block got error code 0x10
>      gr_block_executor: source <gr_block gr uhd usrp source 
> (1)> produced no output.  We're marking it DONE.
> 
> I've tried leaving A and B connected the entire time, 
> connecting B before disconnecting A, disconnecting A before 
> connecting B, but none of these have alleviated the issue.  
> The error messages don't typically occur until we've switched 
> to B.  Also, I've been unable to find what either of these 
> error codes stand for in the GR and UHD documentation.
> 
> I get this error whether I'm running the program on one or 
> both of the E100s.  Even when I'm only running it on one of 
> the E100s, it should definitely be detecting something at the 
> rx port, since I'm running it directly there from a noise generator.
> 
> Do you have any idea what these error codes mean or why I 
> might be getting these errors?
> 
> Thank you very much for your help,
> 
> Chris
> 
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