源码：Github

modbus_tk模块 通过modbus-RTU 读取地址，调用后返回反馈数值和故障信息。

modbus_tk模块安装

  pip install pymodbus_tk

Demo

# -*- coding: utf_8 -*-


import serial
import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu

def mod(PORT="com10"):
    #print("加载modbus_tk 完成")
    red = []
    alarm = ""
    try:
        #设定串口为从站
        master = modbus_rtu.RtuMaster(serial.Serial(port=PORT,
        baudrate=9600, bytesize=8, parity='N', stopbits=1, xonxoff=0))
        master.set_timeout(5.0)
        master.set_verbose(True)

        #读保持寄存器 03H 1站号 地址2700 长度0-42
        red = master.execute(1, cst.READ_HOLDING_REGISTERS, 2700, 43) #这里可以修改需要读取的功能码
        #print(red)
        alarm="正常"
        return list(red),alarm

    except Exception as exc:
        #print(str(exc))
        alarm = (str(exc))

    return red, alarm      ##如果异常就返回[],故障信息

if __name__ == "__main__":
    mod()

功能码及使用说明：

• READ_COILS H01 读线圈
• READ_DISCRETE_INPUTS H02 读离散输入
• READ_HOLDING_REGISTERS H03 读寄存器
• READ_INPUT_REGISTERS H04 读输入寄存器
• WRITE_SINGLE_COIL H05 写单一线圈
• WRITE_SINGLE_REGISTER H06 写单一寄存器
• WRITE_MULTIPLE_COILS H15 写多个线圈
• WRITE_MULTIPLE_REGISTERS H16 写多寄存器

#读保持寄存器 03H 1站号 0地址 长度2 
logger.info(master.execute(1, cst.READ_HOLDING_REGISTERS, 0, 2))
#01 03 00 00 00 02 C4 0B

# 读输入寄存器 04H    
logger.info(master.execute(1, cst.READ_INPUT_REGISTERS, 0, 8))
#反馈：01 04 00 00 00 08 F1 CC

# 读线圈寄存器 01H   
logger.info(master.execute(1, cst.READ_COILS, 0, 6))
#反馈：01 01 00 00 00 06 BC 08

#读离散输入寄存器 02H
logger.info(master.execute(1, cst.READ_DISCRETE_INPUTS, 0, 16))
#反馈：01 02 00 00 00 10 79 C6 

# 单个读写寄存器操作 06H
# 写寄存器地址为0的保持寄存器 06H  
logger.info(master.execute(1, cst.WRITE_SINGLE_REGISTER, 0, output_value=6))
#反馈：01 06 00 00 00 06 09 C8
 
logger.info(master.execute(1, cst.READ_HOLDING_REGISTERS, 0, 1))
#反馈：01 03 00 00 00 01 84 0A

# 写寄存器地址为0的线圈寄存器，写入内容为0（位操作） 05H
logger.info(master.execute(1, cst.WRITE_SINGLE_COIL, 0, output_value=0))
#反馈：01 05 00 00 00 00 CD CA 

logger.info(master.execute(1, cst.READ_COILS, 0, 1))
#反馈：01 01 00 00 00 01 FD CA

# 多个寄存器读写操作 10H
# 写寄存器起始地址为0的保持寄存器，操作寄存器个数为4
logger.info(master.execute(1, cst.WRITE_MULTIPLE_REGISTERS, 11, output_value=[20,21,22,23]))
#反馈：01 10 00 0B 00 04 08 00 14 00 15 00 16 00 17 AB A9

logger.info(master.execute(1, cst.READ_HOLDING_REGISTERS, 0, 4))
#反馈：01 03 00 00 00 04 44 09 

modbus_tk模块——modbusRTU测试

这次使用RTU做测试，配置杀昂与modbusTCP的方式类似，
源代码直接使用的官方示例代码
https://github.com/ljean/modbus-tk/blob/master/examples/rtuslave_example.py

#!/usr/bin/env python
# -*- coding: utf_8 -*-


import sys

import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu
import serial


PORT = 'COM5'
#PORT = '/dev/ptyp5'

def main():
    """main"""
    logger = modbus_tk.utils.create_logger(name="console", record_format="%(message)s")

    #Create the server
    server = modbus_rtu.RtuServer(serial.Serial(PORT))

    try:
        logger.info("running...")
        logger.info("enter 'quit' for closing the server")

        server.start()

        slave_1 = server.add_slave(1)
        slave_1.add_block('0', cst.HOLDING_REGISTERS, 0, 100)
        while True:
            cmd = sys.stdin.readline()
            args = cmd.split(' ')

            if cmd.find('quit') == 0:
                sys.stdout.write('bye-bye\r\n')
                break

            elif args[0] == 'add_slave':
                slave_id = int(args[1])
                server.add_slave(slave_id)
                sys.stdout.write('done: slave %d added\r\n' % (slave_id))

            elif args[0] == 'add_block':
                slave_id = int(args[1])
                name = args[2]
                block_type = int(args[3])
                starting_address = int(args[4])
                length = int(args[5])
                slave = server.get_slave(slave_id)
                slave.add_block(name, block_type, starting_address, length)
                sys.stdout.write('done: block %s added\r\n' % (name))

            elif args[0] == 'set_values':
                slave_id = int(args[1])
                name = args[2]
                address = int(args[3])
                values = []
                for val in args[4:]:
                    values.append(int(val))
                slave = server.get_slave(slave_id)
                slave.set_values(name, address, values)
                values = slave.get_values(name, address, len(values))
                sys.stdout.write('done: values written: %s\r\n' % (str(values)))

            elif args[0] == 'get_values':
                slave_id = int(args[1])
                name = args[2]
                address = int(args[3])
                length = int(args[4])
                slave = server.get_slave(slave_id)
                values = slave.get_values(name, address, length)
                sys.stdout.write('done: values read: %s\r\n' % (str(values)))

            else:
                sys.stdout.write("unknown command %s\r\n" % (args[0]))
    finally:
        server.stop()

if __name__ == "__main__":
    main()

运行前，先在本机配置好两个虚拟串口，使用的是VSPD将两个虚拟串口进行连接直接在右边COM5与COM6进行添加端口就可以了。配置好后如下所示

代码中选用的是COM5,则MODSCAN选择COM6

然后和另一篇文章一样，输入set_values 1 0 1 12 34 56 ，则可以看到modscan读到的数据有变化