How to use Python to read data from Modbus devices?

To read data from Modbus devices using Python, a third-party Modbus library such as pymodbus can be used, which can connect to Modbus devices through TCP or RTU and then read and write data. Here are some basic steps to read Modbus device data using Pymodbus:

1. Installing the Pymodbus library: You can use the pip command to install the Pymodbus library, such as typing pip install Pymodbus in the command line.
2. Import Modbus Client class: Use from pymodbus.client.sync import Modbus TcpClient or from pymodbus.client.sync import Modbus Serial Client to import Modbus Client class, and select TCP or RTU connection method as needed.
3. Process Data: Extract the required data from the read result, for example, use result.registers to retrieve the data held in the register, and then proceed with further processing or display.

client = ModbusTcpClient('192.168.1.10', port=502)

or

client = ModbusSerialClient(method='rtu', port='/dev/ttyUSB0', baudrate=9600, timeout=1)

Read Data: Use the Modbus Client object's read_comils, read_iscrete_inputs, read_roldingunregisters, or read_input_degisters methods to read data, specifying the starting address and quantity to be read, for example:

# 读取保持寄存器地址为 100，数量为 10 的数据
result = client.read_holding_registers(100, 10)

5. Processing data: Extract the required data from the read results, such as using result.registers to retrieve the data held in registers, and then perform further processing or display.
6. Close Connection: Use the close method of the Modbus Client object to close the connection with the Modbus device. For example,

client.close()

can easily read data from the Modbus device by using the pymodbus library, and perform data processing, storage, or display as needed. It should be noted that when using the Pymodbus library, appropriate connection methods, addresses, and parameters should be set according to the specific application scenario to ensure secure, stable, and reliable communication.