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监测数据采集物联网应用开发步骤(9.2)

Modbus rtu协议开发

本章节在《监测数据采集物联网应用开发步骤(7)》基础上实现可参考《...开发步骤(7)》调试工具，本章节代码需要调用modbus_tk组件，阅读本章节前建议baidu熟悉modbus rtu协议内容

组件安装modbus_tk

pip3 install modbus_tk

验证是否安装成功，python中运行下列代码无异常则安装成功：

import modbus_tk

新建modbus协议管理类com.zxy.comport.ComModBus.py

#! python3
# -*- coding: utf-8 -
'''
Created on 2020年05月10日
@author: zxyong 13738196011
'''
import time,struct
from com.zxy.common import Com_Para
from com.zxy.common.Com_Fun import Com_Fun
from com.zxy.z_debug import z_debug
import modbus_tk.defines as cst
import modbus_tk.modbus_rtu as modbus_rtu

#监测数据采集物联网应用--modbus协议管理类
class ComModBus(z_debug):
    
    def __init__(self):
        pass
        
    @staticmethod
    def get_objAryRtuMaster(inputComPort):        
        master = Com_Fun.GetHashTableNone(Com_Para.objAryRtuMaster, inputComPort)
        if master is None:
            com_at = Com_Fun.GetHashTableNone(Com_Para.htComPort, inputComPort)
            if com_at is not None:
                master = modbus_rtu.RtuMaster(com_at.attSerial)           
                # 设定串口为从站
                master.set_timeout(5.0)
                master.set_verbose(True)
                Com_Fun.SetHashTable(Com_Para.objAryRtuMaster, inputComPort, master)
        return master
    
    #字符串转16进制字节并+crc16校验，传入参数无crc校验
    @staticmethod
    def get_data_com_nocrc(inputComPort, CmdStr):  
        temReturn = None       
        try:  
            com_at = Com_Fun.GetHashTable(Com_Para.htComPort, inputComPort)  
            inputByte = bytes().fromhex(CmdStr)
            inputByte = inputByte + ComModBus._getCrc16(inputByte)
            if com_at.WritePortData(inputByte) > 0:
                temReturn = com_at.attReturnValue                    
                com_at.attReturnValue = None
        except Exception as e:
            temReturn = None
        return temReturn
    
    #字符串转字节发送,ascii发送
    @staticmethod
    def get_data_com_ascii(inputComPort, CmdStr):  
        temReturn = None       
        try:  
            com_at = Com_Fun.GetHashTable(Com_Para.htComPort, inputComPort)
            inputByte = bytes(CmdStr, encoding="utf8")
            if com_at.WritePortDataImmed(inputByte) > 0:
                temReturn = com_at.attReturnValue                    
                com_at.attReturnValue = None
        except Exception as e:
            temReturn = None
        return temReturn
    
    #字符串转16进制字节发送
    @staticmethod
    def get_data_com_hex(inputComPort, CmdStr):     
        temReturn = None    
        try:
            com_at = Com_Fun.GetHashTable(Com_Para.htComPort, inputComPort)  
            inputByte = bytes().fromhex(CmdStr)
            if com_at.WritePortData(inputByte) > 0:
                comValue = com_at.attReturnValue
                if comValue is None:
                    return None
                temReturn = comValue
                com_at.attReturnValue = None
        except Exception as e:
            temReturn = None
        return temReturn
    
    #字节发送
    @staticmethod
    def get_data_com_byte(inputComPort, inputByte):    
        temReturn = None     
        try:
            com_at = Com_Fun.GetHashTable(Com_Para.htComPort, inputComPort)  
            if com_at.WritePortData(inputByte) > 0:
                comValue = com_at.attReturnValue
                if comValue is None:
                    return None
                temReturn = comValue
                com_at.attReturnValue = None
        except Exception as e:
            temReturn = None
        return temReturn
    
    #Modbus 04功能码发送
    @staticmethod
    def get_data_rtu_04(inputComPort, inputModbusAddr, inputModbusBegin, inputModbusLength):
        red = []
        try:
            master = ComModBus.get_objAryRtuMaster(inputComPort)
            if master is not None:
                red = master.execute(int(inputModbusAddr), cst.READ_INPUT_REGISTERS, int(inputModbusBegin), int(inputModbusLength))  # 这里可以修改需要读取的功能码             
                time.sleep(0.1)                
            if isinstance(red, list) or isinstance(red, tuple): 
                return red
            else:
                return [""]
        except Exception as e:
            return [""]
    
    #Modbus 03功能码发送 
    @staticmethod
    def get_data_rtu_03(inputComPort, inputModbusAddr, inputModbusBegin, inputModbusLength):
        read = []
        try:
            master = ComModBus.get_objAryRtuMaster(inputComPort)
            if master is not None:
                read = master.execute(inputModbusAddr, cst.READ_HOLDING_REGISTERS, inputModbusBegin, inputModbusLength)  # 这里可以修改需要读取的功能码             
                time.sleep(0.1)                
            if isinstance(read, list) or isinstance(read, tuple): 
                return read
            else:
                return [""]
        except Exception as e:
            return [""]
    
    #Modbus 写寄存器数据
    @staticmethod
    def set_data_rtu(inputComPort, inputModbusAddr, inputModbusBegin, inputValue):
        read = []
        try:
            master = ComModBus.get_objAryRtuMaster(inputComPort)
            if master is not None:
                # 这里可以修改需要读取的功能码 
                if isinstance(inputValue, list) or isinstance(read, tuple):
                    read = master.execute(inputModbusAddr, cst.WRITE_MULTIPLE_REGISTERS, inputModbusBegin, output_value=inputValue) 
                else:
                    read = master.execute(inputModbusAddr, cst.WRITE_SINGLE_REGISTER, inputModbusBegin, output_value=inputValue)               
            if isinstance(read, list) or isinstance(read, tuple): 
                return read
            else:
                return [""]
        except Exception as e:
            return [""]
        
    @staticmethod
    def set_data_rtu2(inputComPort, inputModbusAddr, inputModbusBegin, inputValue):
        read = []
        try:
            master = ComModBus.get_objAryRtuMaster(inputComPort)
            if master is not None:
                # 这里可以修改需要读取的功能码 
                if isinstance(inputValue, list) or isinstance(read, tuple):
                    read = master.execute(inputModbusAddr, cst.ANALOG_INPUTS, inputModbusBegin, output_value=inputValue) 
                else:
                    read = master.execute(inputModbusAddr, cst.ANALOG_INPUTS, inputModbusBegin, output_value=inputValue)               
            if isinstance(read, list) or isinstance(read, tuple): 
                return read
            else:
                return [""]
        except Exception as e:
            return [""]
        
    @staticmethod
    def _getCrc16(RtuStr):
        b = 0xA001
        # 16位寄存器
        a = 0xFFFF
        for byte in RtuStr:
            # 1、把数据帧中的第一个8位字节与CRC寄存器中的低字节进行异或运算
            a = a ^ byte
            for i in range(8):
                # 3、如果最低位为1：将CRC寄存器与一个预设的固定值（0A001H）进行异或运算
                if a & 0x0001:
                    a = a >> 1
                    a = a ^ b 
                # 2、将CRC寄存器向右移一位，最高位填以0，最低位移出并检测
                else:
                    a = a >> 1
        aa = '0' * (6 - len(hex(a))) + hex(a)[2:]
        # 获取低和高位
        lo, hh = int(aa[:2], 16), int(aa[2:], 16)
        hexbytes = bytes([hh, lo])
        return hexbytes
           
    #高低位 reverse: true高位在前 false低位在前
    @staticmethod
    def ReadFloat(n1, n2, reverse=False):    
        n = '%04x' % n1
        m = '%04x' % n2
        if reverse:
            v = n + m
        else:
            v = m + n
        y_bytes = bytes.fromhex(v)
        y = struct.unpack('!f', y_bytes)[0]
        y = round(y, 6)
        return y
    
    @staticmethod
    def WriteFloat(value, reverse=False):
        y_bytes = struct.pack('!f', value)
        y_hex = ''.join(['%02x' % i for i in y_bytes])
        n, m = y_hex[:-4], y_hex[-4:]
        n, m = int(n, 16), int(m, 16)
        if reverse:
            v = [n, m]
        else:
            v = [m, n]
        return v
    
    @staticmethod
    def ReadDint(n1,m1, reverse=False):
        n ='%04x' % n1
        m = '%04x' % m1
        if reverse:
            v = n + m
        else:
            v = m + n
        y_bytes = bytes.fromhex(v)
        y = struct.unpack('!i', y_bytes)[0]
        return y
    
    @staticmethod
    def WriteDint(value, reverse=False):
        y_bytes = struct.pack('!i', value)
        y_hex = ''.join(['%02x' % i for i in y_bytes])
        n, m = y_hex[:-4], y_hex[-4:]
        n, m = int(n, 16), int(m, 16)
        if reverse:
            v = [n, m]
        else:
            v = [m, n]
        return v

modbus rtu测试案例MonitorDataCmd.py主文件中编写：

from com.zxy.comport.ComModBus import ComModBus

在 if __name__ == '__main__':下添加

        #串口配置参数
        Com_Para.ComPortList = "COM2,9600,8,0,A;COM4,9600,8,2,B"
        #串口连接初始化
        Init_Page.Start_ComPort()
        #Modbus-rtu协议功能测试
        temA01modbus = ComModBus()
        #利用modbus_tk组件获取数据，参数:COM索引,modbus站地址,modbus起始位,modbus长度
        read = temA01modbus.get_data_rtu_03("A",1,0,10)
        print("获取10进制原始返回值=>"+str(read))
        modValue = []
        iIndex = 0.0
        n1 = 0
        n2 = 0
        for temSV in read:
            if iIndex % 2 != 0:
                n2 = int(temSV)
                #16进制单精转浮点
                temMV = temA01modbus.ReadFloat(n1,n2,True)
                modValue.append(temMV)
            else:
                n1 = int(temSV)
            iIndex = iIndex + 1
        print("获取读到并解析的寄存器浮点数=>"+str(modValue))
        
        #利用modbus指令协议直接通过com口读取数据
        temCmd = "010300A1000A942F"
        bhex = temA01modbus.get_data_com_hex("A",temCmd)
        read = str(binascii.b2a_hex(bhex).decode(Com_Para.U_CODE)).upper()
        print("获取16进制返回值=>"+str(read))

运行测试结果如下图:

14、监测数据采集物联网应用开发步骤(10),物联网,python