Trouble reading Modbus registers: Exception Response(131, 3, GatewayNoResponse)

Question

Hello Stack Overflow community,

I am currently working on a Python script to retrieve data from a Modbus-enabled device, specifically a central measuring unit installed in an electrical cabinet. I am facing an issue where I receive the following error message: "Error reading registers: Exception Response(131, 3, GatewayNoResponse) " The script is intended to read holding registers from the Modbus TCP IP device and print the corresponding values. However, I am encountering difficulties, and the values are not being displayed. Here is the Python code snippet I am using:

from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.client.sync import ModbusTcpClient

def read_modbus_registers(host, port, unit_id, starting_address, register_count):
    # Create a Modbus TCP client
    client = ModbusTcpClient(host, port)

    try:
        # Connect to the Modbus TCP server
        client.connect()

        # Read holding registers
        result = client.read_holding_registers(starting_address, register_count, unit=unit_id)

        if result.isError():
            print("Error reading registers:", result)
        else:
            decoder = BinaryPayloadDecoder.fromRegisters(result.registers, byteorder=Endian.Big)
            uint32_values = [decoder.decode_32bit_uint() for _ in range(register_count // 2)]
            print("32-bit uint values read from Modbus registers:", uint32_values)

    except Exception as e:
        print("Error:", e)

    finally:
        # Close the Modbus TCP connection
        client.close()

# Modbus settings
modbus_host = '192.168.50.6'
modbus_port = 502
modbus_unit_id = 0x01
modbus_starting_address = 0
modbus_register_count = 161

# Call the function to read Modbus registers
read_modbus_registers(modbus_host, modbus_port, modbus_unit_id, modbus_starting_address, modbus_register_count)

`` `

I would appreciate any insights or guidance on why I'm encountering the "GatewayNoResponse" error and how I can successfully retrieve and display the Modbus register values.

I've attempted to read Modbus registers from a central measuring unit in an electrical cabinet using a Python script. Here are the steps I've taken and the observed results:

Script Execution:

Executed the Python script that establishes a connection to the Modbus TCP server. Attempted to read holding registers starting from address 0 with a count of 161. Expected Outcome:

Expected the script to successfully read the Modbus registers and print the corresponding 32-bit unsigned integer values. Actual Outcome:

Encountered the error message: Error reading registers: Exception Response(131, 3, GatewayNoResponse). The script did not print the expected 32-bit unsigned integer values. Any insights into why I'm facing the "GatewayNoResponse" error and guidance on successfully retrieving and displaying Modbus register values would be greatly appreciated.