Python script to redirect data from TCP/IP to a serial port and vice versa

airzoneserial.service

[Unit]
Description=Innobus python tcp serial port gateway
After=multi-user.target

[Service]
Type=idle
Restart=always
RestartSec=3
ExecStart=/usr/bin/python3 /home/pi/innobus/serial_forwarder.py

[Install]
WantedBy=multi-user.target

serial_forwarder.py

#!/usr/bin/env python
"""
Pymodbus Synchronous Serial Forwarder
--------------------------------------------------------------------------

We basically set the context for the tcp serial server to be that of a
serial client! This is just an example of how clever you can be with
the data context (basically anything can become a modbus device).
"""
# --------------------------------------------------------------------------- # 
# import the various server implementations
# --------------------------------------------------------------------------- # 
from pymodbus.server.sync import StartTcpServer as StartServer
from pymodbus.client.sync import ModbusSerialClient as ModbusClient

from pymodbus.datastore.remote import RemoteSlaveContext
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from pymodbus.transaction import ModbusRtuFramer
import pymodbus.constants

# --------------------------------------------------------------------------- # 
# configure the service logging
# --------------------------------------------------------------------------- # 
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.INFO)
#fh = logging.FileHandler('serial.log')
#fh.setLevel(logging.DEBUG)
#log.addHandler(fh)


def run_serial_forwarder():
    # ----------------------------------------------------------------------- #
    # initialize the datastore(serial client)
    # ----------------------------------------------------------------------- #
    client = ModbusClient(method='rtu', port='/dev/ttyUSB0', baudrate=19200, parity='E')
    store = RemoteSlaveContext(client)
    context = ModbusServerContext(slaves=store, single=True)

    # ----------------------------------------------------------------------- #
    # run the server you want
    # ----------------------------------------------------------------------- #
    StartServer(context, address=('0.0.0.0', 5020))


if __name__ == "__main__":
    pymodbus.constants.Defaults.UnitId = 0x01
    run_serial_forwarder()

hi @gpulido

I'm going to try this approach in my not pro Aidoo to make it manageable through Home Assistant.

I got the USB RS485 adapter to connect it to my Raspi Zero. It's the first time I work with this so I'm not really sure about the wiring. My main question is, do I need to connect the + and the gnd? Or it's just A and B ports?

Thanks in advance