I am trying to read data from a server device using python. I feel like my code should be doing something but it gives me this error:

Modbus Error: [Input/Output] Modbus Error: [Invalid Message] No response received, expected at least 4 bytes (0 received)

I’m very sure all of the parameters are correct.

Here is the code I’m trying.

from pymodbus.client import ModbusSerialClient as ModbusClient


# Configure the client with a timeout
client = ModbusClient(
    method='rtu',
    port='COM4',
    stopbits=1,
    bytesize=8,
    parity='E',
    baudrate=115200,
    timeout= 1  # Timeout in seconds
)

# Connect to the client
connection = client.connect()
if connection:
    print("Port Opened...")
else:
    print("Failed to open port")
    client.close()
    exit(1)

# Define the address and quantity to read
address = 36
quantity = 1

# Read holding registers
response = client.read_holding_registers(address, quantity, unit= 0)  # Specify the correct unit

if not response.isError():
    print("Read values:", response.registers)
else:
    print("Failed to read:", response)

# Close the connection
client.close()