Python • Re: Connecting RS485 via Modbus to Mitsubishi

Code:

import timefrom pymodbus.client import ModbusSerialClientdef read_modbus_registers_via_serial(port, baudrate, parity, stopbits, unit_id, start_address, count):    # Create a Modbus Serial client with the specified parameters    client = ModbusSerialClient(        method='rtu',        port=port,        baudrate=baudrate,        parity=parity,        stopbits=stopbits,        bytesize=8,        timeout=1,        rtscts=True    )        try:        # Connect to the client        if not client.connect():            print("Unable to connect to the Modbus server via serial port")            return None        # Read holding registers        response = client.read_holding_registers(start_address, count, slave = unit_id)                if not response.isError():            # Successfully read the registers            return response.registers        else:            print("Error reading Modbus registers")            return None    finally:        # Close the client connection        client.close()# Configuration for the Mitsubishi MELSERVO J4SERIAL_PORT = '/dev/serial0'        # Replace with your actual serial port (e.g., 'COM3' or '/dev/ttyUSB0')BAUDRATE = 115200             # Replace with the baud rate you are usingPARITY = 'N'                # Parity ('N' for None, 'E' for Even, 'O' for Odd)STOPBITS = 2                # Number of stop bits (1 or 2)UNIT_ID = 1                 # The unit ID of your MELSERVO J4START_ADDRESS = 0x6040      # The starting address in hexadecimal (8448 in decimal)REGISTER_COUNT = 1          # We need to read 2 registers to get a 32-bit value# Read registers via serialregisters = read_modbus_registers_via_serial(SERIAL_PORT, BAUDRATE, PARITY, STOPBITS, UNIT_ID, START_ADDRESS, REGISTER_COUNT)if registers:    print("Registers :", registers)else:    print("Failed to read registers")

Code:

from pymodbus.client import ModbusSerialClient as ModbusClientfrom pymodbus.payload import BinaryPayloadBuilderfrom pymodbus.constants import Endianimport timedef write_reg(register_address, value, n_byte):    # Create a builder to pack the value into registers    builder = BinaryPayloadBuilder(byteorder=Endian.BIG, wordorder=Endian.BIG)    if(n_byte == 1):        builder.add_8bit_uint(value)        pass    elif(n_byte == 2):        builder.add_16bit_uint(value)        pass    elif(n_byte == 4):        pass        payload = builder.to_registers()    # Writing the registers    try:        response = client.write_registers(register_address, payload, slave = 1)        if not response.isError():            #print(f"Successfully wrote value {value} to register {hex(register_address)}")            print(f"OK")        else:            #print(f"Error writing registers: {response}")            print(f"Error writing registers: {response}")    except Exception as e:        print(f"Exception: {e}")    passif __name__ == "__main__":    # Create Modbus client instance    client = ModbusClient(        method='rtu',        port='/dev/serial0',        baudrate=115200,        parity='N',        stopbits=2,        bytesize=8,        timeout=1    )    connection = client.connect() # Connect to the serial port    if connection:        print("Connected to the Modbus server")    else:        print("Failed to connect to the Modbus server")        print("Enabling Voltage, Quick Stop", end = ": ")    write_reg(0x6040, 6, 2)    time.sleep(0.2)    print("Setting Switch On", end = ": ")    write_reg(0x6040, 7, 2)    time.sleep(0.2)    print("Servo On", end = ": ")    write_reg(0x6040, 15, 2)    time.sleep(0.2)    print("Setting Home Mode", end = ": ")    write_reg(0x6060, 6, 2)    time.sleep(0.2)    print("Setting Actual Position to 0", end = ": ")    write_reg(0x6040, 31, 2)    time.sleep(0.2)    client.close() # Close the client    pass