Re: [Discuss-gnuradio] pipes

[paul munro]

Ok, I have tried the TCP method with no real success. I have set GNUradio to 
be the client, Labview as the server. They connect, then the python script 
disconnects with errors before any data is communicated. I have tried a 
couple of different methods. 1) no framing or correlator, and
2) with gr.simple_correlator(1024)

My code is as follows:

           # write to fd (socket)
           fd = socket.socket (socket.AF_INET, socket.SOCK_STREAM)
            self.conn = fd.connect(('0.0.0.0',options.socket))
           print "Connecting to:", self.conn
           print "Address:", self.conn
           # sink to file descriptor
           self.dst = gr.file_descriptor_sink (gr.sizeof_gr_complex, 
fd.fileno())
           print ("data to socket")

           self.connect(self.u, self.dst)

          #self.corr = gr.simple_correlator (1024)
           #self.connect(self.u, self.corr, self.dst)


1)when using no correlator the error I get is:
        gr_file_descriptor_sink: Bad file descriptor

2) when using gr.simple_correlator(8) the error is:
        File 
"/usr/local/lib/python2.3/site-packages/gnuradio/gr/basic_flow_graph.py", 
line
        242, in _check_type_match
            raise ValueError, 'source and destination data sizes are 
different'

> From what I can gather, Labview reads x bytes (8 in my case) in string 
format. This string can then be recast to complex. I have done this reading 
from a file and pipes with no problems. I'm not sure if the problem is the 
tcp control or a lower level of gnuradio.

Any suggestions??

Regards Paul




> From: Eric Blossom <address@hidden>
> To: paul munro <address@hidden>
> CC: address@hidden
> Subject: Re: [Discuss-gnuradio] pipes
> Date: Tue, 4 Jul 2006 06:54:52 -0700
>
> On Tue, Jul 04, 2006 at 06:44:55AM +0000, paul munro wrote:
> > Is there a way of sending the data from the USRP to another application
> > using pipes?? I only know the basics of pipes, and need to look into it
> > more. I was going to try using TCP but thought pipes maybe easier. Also,
> > labview (the app i am sending it to) expects data over the TCP port to 
> be
> > in string format, which is another headache I'm not really prepared to
> > tackle.
> > My main issue is whether pipes can be done in using the available 
> GNURadio
> > libraries. I am guessing it maybe achieved using the
> > gr_file_descriptor_sink(), but I'm not sure how to write to the pipe 
> using
> > this.
> >
> > Any ideas??
> > Regards Paul
>
> Hi Paul, you can use pipes or TCP.  I suggest TCP, it's really no
> problem.  In both cases, open the pipe / socket in python, then use
> the foo.fileno() method to get the file descriptor.  Use the file
> descriptor with gr.file_descriptor_sink
>
> Eric

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