uModbus

Quickstart

#!/usr/bin/env python
# scripts/examples/simple_tcp_server.py
import logging
from socketserver import TCPServer
from collections import defaultdict
from argparse import ArgumentParser
from umodbus import conf
from umodbus.server.tcp import RequestHandler, get_server
from umodbus.utils import log_to_stream
# Add stream handler to logger 'uModbus'.
log_to_stream(level=logging.DEBUG)
# A very simple data store which maps addresses against their values.
data_store = defaultdict(int)
# Enable values to be signed (default is False).
conf.SIGNED_VALUES = True
# Parse command line arguments
parser = ArgumentParser()
parser.add_argument("-b", "--bind", default="localhost:502")
args = parser.parse_args()
if ":" not in args.bind:
 args.bind += ":502"
host, port = args.bind.rsplit(":", 1)
port = int(port)
TCPServer.allow_reuse_address = True
try:
 app = get_server(TCPServer, (host, port), RequestHandler)
except PermissionError:
 print("You don't have permission to bind on {}".format(args.bind))
 print("Hint: try with a different port (ex: --bind localhost:50200)")
 exit(1)
@app.route(slave_ids=[1], function_codes=[1, 2], addresses=list(range(0, 10)))
def read_data_store(slave_id, function_code, address):
 """" Return value of address. """
 return data_store[address]
@app.route(slave_ids=[1], function_codes=[5, 15], addresses=list(range(0, 10)))
def write_data_store(slave_id, function_code, address, value):
 """" Set value for address. """
 data_store[address] = value
if __name__ == '__main__':
 try:
 app.serve_forever()
 finally:
 app.shutdown()
 app.server_close()

#!/usr/bin/env python
# scripts/examples/simple_tcp_client.py
from argparse import ArgumentParser
from socket import create_connection
from umodbus import conf
from umodbus.client import tcp
# Enable values to be signed (default is False).
conf.SIGNED_VALUES = True
# Parse command line arguments
parser = ArgumentParser()
parser.add_argument("-a", "--address", default="localhost:502")
args = parser.parse_args()
if ":" not in args.address:
 args.address += ":502"
host, port = args.address.rsplit(":", 1)
port = int(port)
# Returns a message or Application Data Unit (ADU) specific for doing
# Modbus TCP/IP.
message = tcp.write_multiple_coils(slave_id=1, starting_address=1, values=[1, 0, 1, 1])
with create_connection((host, port)) as sock:
 # Response depends on Modbus function code. This particular returns the
 # amount of coils written, in this case it is.
 response = tcp.send_message(message, sock)

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