Demo

scratchpad_1.py

import asyncio
import threading

status = 0

def set_interval(func, sec):
    def func_wrapper():
        set_interval(func, sec)
        func()
    t = threading.Timer(sec, func_wrapper)
    t.start()
    return t

def modbus_read():
    global status
    while status != 0:
        print('waiting')
    status = -1
    print("reading from mod_bus")
    status = 0

def modbus_write():
    global status
    while status != 0:
        print('waiting')
    status = 1
    print("writing to mod_bus")
    status = 0

def on_message():
    modbus_write()

@asyncio.coroutine
def main():
    set_interval(modbus_read, 1)

set_interval(on_message, 5)
loop = asyncio.get_event_loop()
future = asyncio.Future()
asyncio.async(main())
loop.run_forever()
loop.close()