pymodbus简单使用

pymodbus 是一个基于Python的开源Modbus协议实现库，主要用于工业自动化领域的设备通信。它支持Modbus RTU/ASCII over Serial（串口）及Modbus TCP/IP（以太网）协议，提供客户端（主站）和服务器（从站）功能，适用于PLC、传感器、仪表等设备的读写操作。其设计目标是为开发者提供轻量级、高灵活性的Modbus通信解决方案。

典型应用场景

• 工业自动化：与PLC（如西门子、三菱）通信，采集温度、压力数据。
• 能源监控：读取电表、水表的Modbus寄存器数据。
• 物联网网关：通过TCP将串口设备接入云端。

连接设备：

from pymodbus.client import ModbusTcpClient
from pymodbus.bit_read_message import ReadCoilsResponse
from pymodbus.register_read_message import ReadInputRegistersResponse
from pymodbus.exceptions import ConnectionException      # 连接失败，用于异常处理

host = '127.0.0.1'#设备IP地址
port = 502
client = ModbusTcpClient(host,port)

if client.connect():
    print("Modbus RTU Client Connected")
else:
    print("Failed to connect to Modbus RTU Client")

读线圈

response = client.read_coils(address=1, count=5, unit=1)
if not response.isError():   
    print("coils Values: ", response.bits )
else:
    print("Failed to read registers")

写线圈：

write_response = client.write_coil(address=1, value=True, unit=1)#SM
if not write_response.isError():
    print("Written successfully")
else:
    print("Failed to write coils")

写多个线圈：

values = [True, False, False, True, False]
write_response = client.write_coils(address=1, values=values, unit=1)
if not write_response.isError():
    print("Multiple registers written successfully")
else:
    print("Failed to write multiple registers")

读寄存器：

response = client.read_holding_registers(address=1, count=5, unit=1)
if not response.isError():
    print("Register Values: ", response.registers)
else:
    print("Failed to read registers")

写寄存器：

write_response = client.write_register(address=41088, value=25, unit=1)
if not write_response.isError():
    print("Written successfully")
else:
    print("Failed to write register")

写多个寄存器：

values = [17,23, 40, 60, 80, 100]
write_response = client.write_registers(address=41088, values=values, unit=1)
if not write_response.isError():
    print("Multiple registers written successfully")
else:
    print("Failed to write multiple registers")