[Discuss-gnuradio] Help needed with message ports

[Volker Schroer]

Hi,

I'm trying to add an message port to my  working oot module fcdproplus 
to be able to control the frequency by an message from a qtgui sink.

I used the analog signal source as guide and implemented a message sink 
in the grc description, registered the in port, and defined  a handler 
function like described in the tutorial.

I can run my example of a simple fm receiver as before, but when I 
connect the message out port of a qtgui sink to my message in port of my 
oot block,

I get the following error message:


./FMRadio.py
INFO: Audio source arch: alsa
Funcube Dongle Pro+ found as: plughw:3,0
Dongle sucessfully initialized
Result of Action :+++++
FCDAPP 20.03
 Lna gain enabled
 Mixer gain enabled
If gain set to: 10
Set Frequency to: 94.3 KHz, corrected to: 94300 Khz
INFO: Audio sink arch: alsa
Traceback (most recent call last):
  File "./FMRadio.py", line 277, in <module>
    main()
  File "./FMRadio.py", line 266, in main
    tb.start()
  File 
"/usr/local/gnuradio/lib64/python2.7/site-packages/gnuradio/gr/top_block.py", 
line 109, in start
    top_block_start_unlocked(self._impl, max_noutput_items)
  File 
"/usr/local/gnuradio/lib64/python2.7/site-packages/gnuradio/gr/runtime_swig.py", 
line 5678, in top_block_start_unlocked
    return _runtime_swig.top_block_start_unlocked(r, max_noutput_items)
RuntimeError: fcdproplus(3): insufficient connected output ports (1 
needed, 0 connected)

These are the connections:


       ##################################################
        # Connections
        ##################################################
        self.msg_connect((self.qtgui_sink_x_0, 'freq'), 
(self.fcdproplus_fcdproplus_0, 'freq'))
        self.connect((self.analog_fm_demod_cf_0, 0), 
(self.audio_sink_0, 0))
        self.connect((self.analog_fm_demod_cf_0, 0), 
(self.audio_sink_0, 1))
        self.connect((self.fcdproplus_fcdproplus_0, 0), 
(self.low_pass_filter_0, 0))
        self.connect((self.fcdproplus_fcdproplus_0, 0), 
(self.qtgui_sink_x_0, 0))
        self.connect((self.low_pass_filter_0, 0), 
(self.analog_fm_demod_cf_0, 0))

If I remove the line

self.msg_connect((self.qtgui_sink_x_0, 'freq'), 
(self.fcdproplus_fcdproplus_0, 'freq'))


from my python script he error message disappears.

What am I doing wrong?


Any help is appreciated.

-- Volker