Use pymodbus to access modbus rtu device

pymodbus_rtu.py

#!/usr/bin/env python

from pymodbus.client.sync import ModbusSerialClient

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

client = ModbusSerialClient(method='rtu', port='/dev/ttyM0', baudrate=38400, parity='N', bytesize=8, stopbits=1, timeout=1)
client.connect()

rd = client.read_discrete_inputs(1, 1, unit=1)
print (repr(rd.bits))

client.close()