GUI not starting when trying to display a console message

Question

I have managed to get the response from the radio and I can read the current frequency into a console. Now I would like to display that output into a label or similar, without clicking on a button or something. I have a separate file with the GUI interface but if I try to display the output the GUI doesn't run. I have googled quite a lot but I can't figure out how yet, any help will be much appreciated. I have included the code to read from radio.

import serial
import time

comPort = 'COM4'
comBaud = 115200
icomCivAddress = 148

ser = serial.Serial(comPort, comBaud)
 
ser.setDTR(False) # Prevent TCVR cw send if USB key is set on DTR
ser.setRTS(False) # Prevent TCVR going transmit if USB key is set on RTS
  

def readFromIcom():
    time.sleep(0.04)
    b = bytearray()
    while ser.inWaiting():
        b = b + ser.read()
    while b.count(b'\xfd') > 1:
        del b[0:b.find(b'\xfd') + 1]
        if len(b) > 0:
            validMsg = bytes([254, 254, 224, icomCivAddress, 0, 253])
            if b[0:5] == validMsg:
                b = b[6:len(b)]
                if len(b) > 0:
                    if b[0] == 254 and b[1] == 254 and b[-1] == 253:
                        return b
                    else:
                        b = bytearray()
                else:
                    b = bytearray()
            else:
                if b[0] == 254 and b[1] == 254 and b[-1] == 253:
                    b = b
                else:
                    b = bytearray()
    return b

def writeToIcom(b):
    s = ser.write(bytes([254, 254, icomCivAddress, 224]) + b + bytes([253]))
    return readFromIcom()

def getFrequency():
    b = writeToIcom(b'\x03')
    c = ''
    if len(b) > 0:
        for a in reversed(b[5:9]):
            c = c + '%0.2X' % a
    if len(c) > 0:
        if c[0] == '0':
            c = c[0:len(c)]     # To show the exact numbers position even if below 10Mhz need to put 0
    return c

freq = 1
while freq == 1:
    c = getFrequency()
    print('Frequency: ' + c[0:1] + c[1:2] + "." + c[2:3] + c[3:4] + c[4:5] + "." + c[5:6] + c[6:7] + c[7:8])
else:
    print('No response from Radio!')