python tcp协议_modbus-tcp协议学习-python
原文链接：http://blog.csdn.net/qq_20101209/article/details/62055069
1. 前言
modbus_tk是使用python语言实现的modbus协议栈，该库函数及支持主机也支持从机，同时支持RTU串口通信和TCP范式通信。
2. 准备工作
查阅modbus相关资料
下载modbus-tcp tester，这里面有server-tester和client-tester，能加速测试程序过程
3. modbus_tk安装
环境：python2.7, win10 & 树莓派
操作：直接 pip install modbus_tk 或者采用 easy_install
4. 基础示例
从机程序，需要先运行从机程序，才能启动master
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48#!/usr/bin/env python
# -*- coding: utf_8 -*-
''' 作者：raphael 时间：2017/3/10 简介：modbus协议从机测试脚本 '''
import sys
import logging
import threading
import modbus_tk
import modbus_tk.defines as cst
import modbus_tk.modbus as modbus
import modbus_tk.modbus_tcp as modbus_tcp
LOGGER = modbus_tk.utils.create_logger(name="console", record_format="%(message)s")
if __name__ == "__main__":
try:
# server里的address需要写的树莓派的IP和需要开放的端口，注意开放相应的端口
SERVER = modbus_tcp.TcpServer(address="192.168.1.111", port=1100)
LOGGER.info("running...")
LOGGER.info("enter 'quit' for closing the server")
# 服务启动
SERVER.start()
# 建立第一个从机
SLAVE1 = SERVER.add_slave(1)
SLAVE1.add_block('A', cst.HOLDING_REGISTERS, 0, 4)#地址0，长度4
SLAVE1.add_block('B', cst.HOLDING_REGISTERS, 4, 14)
#建立另一个从机2
SLAVE2 = SERVER.add_slave(2)
SLAVE2.add_block('C', cst.COILS, 0, 10) #地址0，长度10
SLAVE2.add_block('D', cst.HOLDING_REGISTERS, 0, 10)#地址0，长度10
SLAVE1.set_values('A', 0, 4) #改变在地址0处的寄存器的值
SLAVE1.set_values('B', 4, [1, 2, 3, 4, 5, 5, 12, 1232]) #改变在地址4处的寄存器的值
SLAVE2.set_values('C', 0, [1, 1, 1, 1, 1, 1])
SLAVE2.set_values('D', 0, 10)
while True:
CMD = sys.stdin.readline()
if CMD.find('quit') == 0:
sys.stdout.write('bye-bye\r\n')
break
else:
sys.stdout.write("unknown command %s\r\n" % (args[0]))
finally:
SERVER.stop()
主机程序
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36#!/usr/bin/env python
# -*- coding: utf_8 -*-
'''
作者：raphael
时间：2017/3/10
简介：modbus协议主机测试脚本
'''
import sys
import logging
import modbus_tk
import modbus_tk.defines as cst
import modbus_tk.modbus_tcp as modbus_tcp
LOGGER = modbus_tk.utils.create_logger("console")
if __name__ == "__main__":
try:
#连接从机地址,这里要注意端口号和IP与从机一致
MASTER = modbus_tcp.TcpMaster(host="192.168.1.111", port=1100)
MASTER.set_timeout(5.0)
LOGGER.info("connected")
#读取从机1的0-4保持寄存器
LOGGER.info(MASTER.execute(1, cst.READ_HOLDING_REGISTERS, 0, 4))
#读取从机1的4-14保持寄存器，因为寄存器独立分块了，所以不能直接连通读取，强行结果是会出现数据越界
LOGGER.info(MASTER.execute(1, cst.READ_HOLDING_REGISTERS, 4, 14))
# 需要按照execute格式
LOGGER.info(MASTER.execute(1, cst.WRITE_MULTIPLE_REGISTERS, 0, output_value=[0, 1, 2]))
LOGGER.info(MASTER.execute(1, cst.READ_HOLDING_REGISTERS, 0, 4))
LOGGER.info(MASTER.execute(2, cst.READ_COILS, 0, 8))
LOGGER.info(MASTER.execute(2, cst.WRITE_MULTIPLE_COILS, 0, output_value=[1, 0, 0, 0, 1]))
LOGGER.info(MASTER.execute(2, cst.READ_COILS, 0, 8))
LOGGER.info(MASTER.execute(2, cst.READ_HOLDING_REGISTERS, 0, 4))
# 线圈和寄存器地址不是同一区块的
except modbus_tk.modbus.ModbusError, err:
LOGGER.error("%s- Code=%d" % (err, err.get_exception_code()))
5.结果截图
主机
从机
6. 相关函数说明
add_slave(self, slave_id, unsigned=True, memory=None)
注意id区间
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10def add_slave(self, slave_id, unsigned=True, memory=None):
"""Add a new slave with the given id"""
with self._lock:
if (slave_id <= 0) or (slave_id > 255):
raise Exception("Invalid slave id {0}".format(slave_id))
if slave_id not in self._slaves:
self._slaves[slave_id] = Slave(slave_id, unsigned, memory)
return self._slaves[slave_id]
else:
raise DuplicatedKeyError("Slave {0} already exists".format(slave_id))
set_values(self, block_name, address, values)
If values is a number, only one value is written,对于这个函数, values是我已开始没清楚的
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29def set_values(self, block_name, address, values):
""" Set the values of the items at the given address If values is a list or a tuple, the value of every item is written If values is a number, only one value is written """
# thread safe
with self._data_lock:
block = self._get_block(block_name)
# the block has been found
# check that it doesn't write out of the block
offset = address-block.starting_address
size = 1
if isinstance(values, list) or isinstance(values, tuple):
size = len(values)
if (offset < 0) or ((offset + size) > block.size):
raise OutOfModbusBlockError(
"address {0} size {1} is out of block {2}".format(address, size, block_name)
)
# if Ok: write the values
if isinstance(values, list) or isinstance(values, tuple):
block[offset:offset+len(values)] = values
else:
block[offset] = values
execute( self, slave, function_code, starting_address, quantity_of_x=0, output_value=0, data_format=”“, expected_length=-1)
参数
注释
备注
slave
从机地址
modbus_tcp时可以忽略
function_code
功能码
看定义
starting_address
寄存器初始地址
要注意块界限
quantity_of_x
寄存器或者线圈数量
output_value
输出内容
注意写的类型
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10@threadsafe_function
def execute( self, slave, function_code, starting_address, quantity_of_x=0, output_value=0, data_format="", expected_length=-1):
""" Execute a modbus query and returns the data part of the answer as a tuple The returned tuple depends on the query function code. see modbus protocol specification for details data_format makes possible to extract the data like defined in the struct python module documentation """
7.modbus 功能代码： defines.py
modbus 异常代码
ILLEGAL_FUNCTION = 1 功能代码不合法
ILLEGAL_DATA_ADDRESS = 2 数据地址不合法
ILLEGAL_DATA_VALUE = 3 数据值不合法
SLAVE_DEVICE_FAILURE = 4 slave设备失败
COMMAND_ACKNOWLEDGE = 5 命令已收到
SLAVE_DEVICE_BUSY = 6 slave设备忙
MEMORY_PARITY_ERROR = 8 内存奇偶误差
supported modbus 功能代码
READ_COILS = 1 读线圈
READ_DISCRETE_INPUTS = 2 读离散输入
READ_HOLDING_REGISTERS = 3 【读乘法寄存器】
READ_INPUT_REGISTERS = 4 读输入寄存器
WRITE_SINGLE_COIL = 5 写单一线圈
WRITE_SINGLE_REGISTER = 6 写单一寄存器
WRITE_MULTIPLE_COILS = 15 写多个线圈 【强制多点线圈】
WRITE_MULTIPLE_REGISTERS = 16 写多寄存器 【写乘法寄存器】
supported block types 支持的块类型
COILS = 1 线圈
DISCRETE_INPUTS = 2 离散输入(数字量输入)
HOLDING_REGISTERS = 3 乘法寄存器
ANALOG_INPUTS = 4 模拟量输入
8.参考网址