User How to send data from Modbus TCP to Modbus RTU in Python 3

To send data from Modbus TCP to Modbus RTU in Python, you'll need to use appropriate libraries for Modbus communication. Two popular libraries for Modbus communication in Python are minimalmodbus and pymodbus. Here, I'll show you how to use pymodbus to send data from Modbus TCP to Modbus RTU.

First, make sure you have the required libraries installed:

------------------------------

pip install pymodbus pyserial

-----------------------------

Now, let's create a simple example where a Modbus TCP client sends data to a Modbus RTU server. Make sure you have a physical or virtual serial port available for the Modbus RTU communication.

Modbus RTU Server (Slave)

----------------------------------------

from pymodbus.server.sync import StartTcpServer

from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext

from pymodbus.datastore import ReadableData, WritableData

# Create a simple Modbus RTU server context

store = ModbusSlaveContext(

    di=ReadableData(1, {0: 0}),

    co=WritableData(1, {0: 0}),

    hr=WritableData(1, {0: 0}),

    ir=WritableData(1, {0: 0})

)

context = ModbusServerContext(slaves=store, single=True)

# Start the Modbus RTU server on a serial port

with StartTcpServer(context) as server:

    print("Modbus RTU server started on port 502...")

    server.serve_forever()

-------------------------------------------------------------

Modbus TCP Client (Master) : 

----------------------------------------------------------

from pymodbus.client.sync import ModbusTcpClient

# Modbus RTU server address (change accordingly)

rtu_server_ip = "127.0.0.1"

rtu_server_port = 502

# Modbus RTU slave address (change accordingly)

rtu_slave_address = 1

# Connect to the Modbus RTU server over TCP

rtu_client = ModbusTcpClient(rtu_server_ip, port=rtu_server_port)

try:

    # Write data to a Modbus RTU register (change accordingly)

    rtu_client.write_register(0, 123, unit=rtu_slave_address)

    print("Data sent to Modbus RTU server.")

except Exception as e:

    print(f"Error: {e}")

finally:

    rtu_client.close()

--------------------------------------------------------------

This example creates a Modbus RTU server using pymodbus on a TCP port (502 by default). The Modbus TCP client connects to this server and writes data to a Modbus RTU register.

Please note:

- Update rtu_server_ip and rtu_server_port in the client code according to the IP address and port where your Modbus RTU server is running.

- Adjust the Modbus RTU slave address (rtu_slave_address) and the Modbus RTU register address (write_register(0, 123, unit=rtu_slave_address)) as needed for your specific Modbus RTU setup.

Ensure that you have the necessary permissions to access serial ports on your system. If you're using a physical serial port, ensure the correct COM port is specified in the Modbus RTU server code. If you're using a virtual serial port, adjust the server code accordingly.