append answer from pcb in while loop

Question

upper_bound = 0x1200
lower_bound = 0x0
msg_to_send = rcvD.all_strck.MxFEAxiRegMsg.copy()
modem_snr_list = []
while True:
    modem_snr_list.clear()
    running_value = (upper_bound + lower_bound) // 2
    msg_to_send["data"] = running_value
    # rcvD.send_the_message("MxFEAxiRegMsg",  rcvD.all_strck.MxFEAxiRegMsg)
    rcvD.send_the_message("MxFEAxiRegMsg", msg_to_send)
    time.sleep(2)
    fm.rcv_the_packets(wait_for_optcode=38)
    fm.rcv_the_packets(wait_for_optcode=90)
    modem_sync = rcvD.all_strck.modemParamMsg["modemSync"]
    modem_freq = rcvD.all_strck.modemParamMsg["modemEstFreq"]
    modem_snr = rcvD.all_strck.modemParamMsg["modemSnr"]
    modem_snr_list.append(modem_snr)
    average_snr = sum(modem_snr_list) / len(modem_snr_list)
    print(f"modem snr list is {modem_snr_list}\n modem snr average is {average_snr}")

    sent_pack = rcvD.all_strck.dataStatusRepMsg["sentMsgCnt"]
    receive_pack = rcvD.all_strck.dataStatusRepMsg["rcvMsgCnt"]

    print(
        f"msg_sent: {msg_to_send} \n running_value: {running_value}\n upper_bound: {upper_bound}\n lower_bound: {lower_bound}\n modem_snr: {modem_snr}\n modem_freq: {modem_freq}\n modem_sync: {modem_sync}\n "
        f"sent_packets: {sent_pack}\n receive_packets: {receive_pack}")

    if -1 < modem_snr < 1 and modem_sync and modem_freq < 1000 and sent_pack == receive_pack:
        break

    if modem_snr < -1:
        lower_bound = running_value + 1
    if modem_snr > 1:
        upper_bound = running_value - 1

    if upper_bound < lower_bound:
        print("FAIL")
        exit(1)

Hi all, I need to catch the answer from PCB(opcode 38) because of timing I prefer to send a data(msg_sent) than to do some list that appends received data, calculate the average, and after all this proceed to the if statements(instead of modem_snr will be average_snr), after that if I need to back to while to fix data, I will need to clear the previous list and repeat the circle.