python linux 上 RS485通信 Modbus协议

Posted 2022-03-10 qq61308aba0f7f4

如题:

CRC计算参考了这篇文章

后来发现在读取的时候会出问题, 所以引入了. serial

import struct
import platform
import time
import serial #导入模块


sysstr = platform.system()

#RS485文件的通信地址,在开发板上是/dev/ttysWK0
if(sysstr=="Windows"):
    RS485FileName = "COM1"
elif(sysstr =="Linux"):
    RS485FileName = "/dev/ttysWK0"
    # RS485：/dev/ttysWK0
    # RS232：/dev/ttysWK1
    # UART2：/dev/ttysWK3
    # UART1：/dev/ttysWK2
else:
    RS485FileName = "/dev/ttysWK0"





# ===============================================================
def CalCRC16(data, length):
    #print(data, length)                          #打印数据，长度
    crc=0xFFFF
    if length == 0:
       length = 1
    j = 0
    while length != 0:
        crc ^= list.__getitem__(data, j)
        #print(j=0x%02x, length=0x%02x, crc=0x%04x %(j,length,crc))
        for i in range(0,8):
            if crc & 1:
                crc >>= 1
                crc ^= 0xA001
            else:
                crc >>= 1
        length -= 1
        j += 1
    return crc
# ===============================================================
def CRCBuffer(buffer):     
    crc_transformation = CalCRC16(buffer,len(buffer))    
    #crc_calculation = hex(crc_transformation)
    #print(crc_calculation:,crc_calculation)
    tasd = [0x00,0x00]
    tasd[0] = crc_transformation & 0xFF
    tasd[1] = (crc_transformation >> 8) & 0xFF
    H =hex(tasd[0])
    L =hex(tasd[1])
    H_value = int(H,16)
    L_value = int(L,16)
    buffer.append(H_value)
    buffer.append(L_value)
    return buffer
# ===============================================================


# if __name__ == __main__:

#     print(CRCBuffer(buffer))
def Send485CMD_OLD(cmd): 
    global RS485FileName   

    with open(RS485FileName, "wb") as rs485:  

        buffercrc = CRCBuffer(cmd)   
        ret = rs485.write(bytes(buffercrc))
        rs485.close()
        return ret

def SendAndRead485CMD(cmd):
    global RS485FileName   

    ser = serial.Serial(RS485FileName,9600,timeout=10)
    buffercrc = CRCBuffer(cmd)
    print("RS485 TX =>", bytes(bytearray(buffercrc)))
    ser.write(buffercrc) # 这里直接发送int类型的数据, 内部会自动转换成byte字节.
    # ret = ser.write(bytes(buffercrc))  
    time.sleep(0.2)
    res = ser.read_all()
    print("RS485 RX =>", res)

    ser.close()
    return res

def ReadGateSate(gatenum):
    cmd = [ 
            gatenum, #设备地址=\\x00# 0x00 is guang bo
            0x03, #功能码=\\x06 #\\06 is write, \\03 is read, \\10 is write mutil 
            0x00, #寄存器地址高=\\x00
            0x18, #寄存器地址低=\\x0E #0E is open door cmd
            0x00, #数据高=\\x00
            0x01, #数据低=\\x01 
            # 0x00, #CRC高=\\x00
            # 0x00, #CRC低=\\x00
        ]
    return SendAndRead485CMD(cmd)


def OpenTheDoor(gatenum):
    cmd = [ 
            gatenum, #设备地址=\\x00# 0x00 is guang bo
            0x06, #功能码=\\x06 #\\06 is write, \\03 is read, \\10 is write mutil 
            0x00, #寄存器地址高=\\x00
            0x0E, #寄存器地址低=\\x0E #0E is open door cmd
            0x00, #数据高=\\x00
            0x01, #数据低=\\x01 
            # 0x00, #CRC高=\\x00
            # 0x00, #CRC低=\\x00
        ] 
    SendAndRead485CMD(cmd);   
    pass

def CloseTheDoor(gatenum):
    cmd = [ 
            gatenum, #设备地址=\\x00# 0x00 is guang bo
            0x06, #功能码=\\x06 #\\06 is write, \\03 is read, \\10 is write mutil 
            0x00, #寄存器地址高=\\x00
            0x0E, #寄存器地址低=\\x0E #0E is open door cmd
            0x00, #数据高=\\x00
            0xFF, #数据低=\\x01 
            # 0x00, #CRC高=\\x00
            # 0x00, #CRC低=\\x00
        ] 
    SendAndRead485CMD(cmd);   
    pass

def OpenTheLid(gatenum):  
    cmd = [ 
            gatenum, #设备地址=\\x00# 0x00 is guang bo
            0x06, #功能码=\\x06 #\\06 is write, \\03 is read, \\10 is write mutil 
            0x00, #寄存器地址高=\\x00
            0x0E, #寄存器地址低=\\x0E #0E is open door cmd
            0x00, #数据高=\\x00
            0x01, #数据低=\\x01 
            # 0x00, #CRC高=\\x00
            # 0x00, #CRC低=\\x00
        ] 
    SendAndRead485CMD(cmd)
    pass

def CloseTheLid(gatenum):
    cmd = [ 
            gatenum, #设备地址=\\x00# 0x00 is guang bo
            0x06, #功能码=\\x06 #\\06 is write, \\03 is read, \\10 is write mutil 
            0x00, #寄存器地址高=\\x00
            0x0E, #寄存器地址低=\\x0E #0E is open door cmd
            0x00, #数据高=\\x00
            0xFF, #数据低=\\x01 
            # 0x00, #CRC高=\\x00
            # 0x00, #CRC低=\\x00
        ] 
    SendAndRead485CMD(cmd);   
    pass


res = OpenTheDoor(0x04)
res = ReadGateSate(0x04)