I got it. If the message port defined in grextras is disconnected, the
message sink or source block will not in the flowgraph.
Thanks Tom.
Best regards,
Damon
On Thu, Apr 24, 2014 at 12:01 AM, Damon <qiu.guowang...@gmail.com
<mailto:qiu.guowang...@gmail.com>> wrote:
Hi Tom,
Thanks for you reply.
I am wondering why the data stream ports of byte or integer 8
could be disconnected by other ports.
Here is an example. The connecting code is commented out, but we
can run this program without getting a error.
#!/usr/bin/env python
##################################################
# Gnuradio Python Flow Graph
# Title: Top Block
# Generated: Thu Apr 24 11:57:08 2014
##################################################
from gnuradio import blocks
from gnuradio import eng_notation
from gnuradio import gr
from gnuradio.eng_option import eng_option
from gnuradio.filter import firdes
from optparse import OptionParser
class top_block(gr.top_block):
def __init__(self):
gr.top_block.__init__(self, "Top Block")
##################################################
# Variables
##################################################
self.samp_rate = samp_rate = 32000
##################################################
# Blocks
##################################################
self.blocks_null_source_0 =
blocks.null_source(gr.sizeof_char*1)
self.blocks_null_sink_0 = blocks.null_sink(gr.sizeof_char*1)
##################################################
# Connections
##################################################
#self.connect((self.blocks_null_source_0, 0),
(self.blocks_null_sink_0, 0))
# QT sink close method reimplementation
def get_samp_rate(self):
return self.samp_rate
def set_samp_rate(self, samp_rate):
self.samp_rate = samp_rate
if __name__ == '__main__':
parser = OptionParser(option_class=eng_option, usage="%prog:
[options]")
(options, args) = parser.parse_args()
tb = top_block()
tb.start()
raw_input('Press Enter to quit: ')
tb.stop()
tb.wait()
Best regards,
Damon
I really don't understand the question. Why do you think this behavior
is wrong? There are no blocks in the flowgraph; that's not a condition
to say it won't run. When you hit start, it'll try to start all
threads; there are none, so it will immediately exit. The raw_input is
a Python thing, so that will continue to block.
Tom
2014-04-23 21:46 GMT+08:00 Tom Rondeau <t...@trondeau.com
<mailto:t...@trondeau.com>>:
On Tue, Apr 22, 2014 at 5:09 AM, Damon
<qiu.guowang...@gmail.com <mailto:qiu.guowang...@gmail.com>>
wrote:
Hi all,
Recently I am learning the grextras project. I am confused
about the
message port which is designed in grextras.
Why will we not get a error when the message ports do not
connect to
other message ports? I thought those port actually is data
stream ports,
so they should be connected to other ports.
Best regards,
Damon
Damon,
grextras is an external project from GNU Radio and not related
to the core functionality.
But GNU Radio's message passing structure does not require
connections. It's a publish-subscribe model, and a block will
publish a message regardless of whether or not another block
is subscribed and listening.
Tom
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