gistfile1.py

#!/usr/bin/env python

from pymodbus.client.sync import ModbusTcpClient

import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

client = ModbusTcpClient('xxx.xxx.xxx.xxx', port=50002)
connected = client.connect()

print("client connected: %s" % connected)

rq = client.write_coil(5, True)
assert(rq != None)
assert(rq.function_code < 0x80)

rr = client.read_coils(5,1)
assert(rr != None)
assert(rr.bits[0] == True)

client.close()