Can't get message passing working when calling a class method from main()

I am attempting to send a message from an OOT module to a gr-display module. This task is part of a large project with a complicated flowgraph. Therefore I am going to provide only the pertinent part of the code. I hope this is sufficient to understand my problem with some explanation.

 

The ft8_rxtx OOT module is connected to the gr-display module in the flowgraph.

 

The code is as follows:

 

from gnuradio import gr
import pmt

class ft8_rxtx(gr.basic_block):
    """
    docstring for block ft8_rxtx
    """
    def __init__(self, ptt_button, band_selector):
        gr.basic_block.__init__(self,
            name="ft8_rxtx",
            in_sig=[],
            out_sig=[])
        self.ptt_button = ptt_button
        self.band_selector = band_selector
        self.portName = "text_out"
        self.message_port_register_out(pmt.intern(self.portName))
 
def set_FT8(self, FT8_button):
        if FT8_button == 1:
            self.send_msg("Help")
            PMT_msg = pmt.to_pmt("Help")
            self.message_port_pub(pmt.intern(self.portName), PMT_msg)
            main()
        else:
            quit()

def send_msg(self, msg):
        PMT_msg = pmt.to_pmt(msg)
        self.message_port_pub(pmt.intern(self.portName), PMT_msg)


def main():

    gen_msg = ft8_rxtx(0,1)
    gen_msg.send_msg("MAIN")

 

In main() I am calling send_msg as evidenced by the use of a print statement in the method which correctly displays MAIN. However, the message_port_pub() does not send the message to the gr-display.

 

If set_FT8 is called, the self.send_msg("Help") executes properly and the self.message_port_pub() executes properly. Both send the message "Help" to the gr-display.

 

Thus, the message passing works when calling send_msg from a class method but does not work when called from main(). Why not? What am I leaving out?

 

Jim

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