viper/uart.py

import serial
import struct
import time
     
class Uart(object):
    def __init__(self,):
        self.ser 		    = serial.Serial()
        self.__buf 		    = b''
        self.command 	    = b''
        self._is_connected  = False
        self.begin_time     = None    
        pass

    def set_serial_para(self, port="COM1",baudrate=9600,bytesize=8,parity="N", stopbit=1, timeout = 4):	
        self.port 			= port
        self.ser.port 		= port
        self.ser.baudrate 	= baudrate
        self.ser.bytesize 	= bytesize
        self.ser.parity 	= parity    
        self.ser.stopbits 	= stopbit
        self.ser.timeout    = timeout
    
    def set_modbus(self, slaveaddress=1, functioncode=3, beginaddress=0, step=5 ):	
        self.slaveaddress 			= slaveaddress
        self.functioncode 			= functioncode
        self.beginaddress 			= beginaddress
        self.step 					= step
        self.command 				= self.__get_modbus_command()
        self.rcv_len 				= 2*self.step + 5   # 16bit

    def connect(self,):	
        try:
            self.ser.open()
            if self.ser.isOpen():
                self._is_connected = True
                self.ser.close()
        except Exception as e:
            self._is_connected = False
            # SerialException(f"KH3000 can not open port :  {self.ser.port}")

        if self.ser is not None and self.ser.isOpen():
            self.ser.close()
        return self._is_connected

    def disconnect(self,):	
        if self._is_connected or self.ser.isOpen():
            self.ser.close()
            self._is_received = False
            self._is_connected = False
        pass

    def write(self,) -> None:
        try:
            self.ser.open()
            if self.ser.isOpen():
                self.ser._is_connected = True
        except Exception as e:
            self.ser. _is_connected = False

        if self.ser._is_connected:
            self.begin_time = time.time()
            self.ser.reset_input_buffer()
            self.ser.reset_output_buffer()
            # print(f"========= command {self.command.hex() }")
            self.ser.write(self.command)
            # if isHex:
            #     data = bytes.fromhex(data)
            #     self.ser.write(bytes(data))
            # else:
            #     self.ser.write(bytes(data, encoding='utf8')+b'\x0A\x0D')

    def receive(self,):	
        self.flush()
        while 1:    
            if not self._is_receiving:
                break         
            if self.ser.in_waiting:   # 这个接收是随机的
                for _ in range(self.ser.in_waiting):
                    # print( type(_serial.read(1)))
                    temp = self.ser.read(1)  # 可以直接读取指定长度
                    self.__buf = self.__buf + temp
                if len(self.__buf) >= self.rcv_len:
                    break
            if time.time() - self.begin_time > self.ser.timeout:
                self.__buf = b''
                break
                
        self._is_receiving = False  

    def OneMeasure(self) -> bytes:
        if not self.ser.isOpen():
           self.ser.open()
        self._is_receiving = True
        self.__buf = b''
        self.receive()
        
        if len(self.__buf)>=self.rcv_len and not self._is_receiving :
            return self.__buf
        
        return b''
        pass

    def reset_input_buffer(self)->None:
        self.ser.reset_input_buffer()
        pass

    def reset_output_buffer(self)->None:
        self.ser.reset_output_buffer()
        pass
  
    def flush(self)->None:
        self.ser.flush()
        pass  
    
    def IsOpen(self)->bool:
        return self._is_connected
        pass

    def IsReceived(self)->bool:
        return self._is_received
        pass
                        
    def getResult(self)->bytes:
        return  self.__buf
        pass

    def add_crc16( self, buf:bytes ):
        '''
        一般发送命令都是'01030000000A'这样的字符串
        输入：test2 = '01030000000A'
        输出：0xc5cd
        hexstr[2:].upper()  去掉
        '''
        crc = 0xFFFF
        for pos in buf:
            crc ^= pos
            for i in range(8):
                if ((crc & 1) != 0):
                    crc >>= 1
                    crc ^= 0xA001
                else:
                    crc >>= 1       
        return  ((crc & 0xff) << 8) + (crc >> 8)  
        # return hex(((crc & 0xff) << 8) + (crc >> 8))[2:].upper()

    def crc16Check(self,buf:bytes):
        if len(buf) > 4 :
            crc = self.add_crc16(buf[:-2])
            if (crc & 0xff) == buf[-1]  and  (crc >> 8)== buf[-2]:
                return True
            else:
                return False
        else:
            return False

    def __get_modbus_command(self, ):
        res = b''
        res = res + self.slaveaddress.to_bytes(1, byteorder="big")
        res = res + self.functioncode.to_bytes(1, byteorder="big")
        res = res + self.beginaddress.to_bytes(2, byteorder="big")
        res = res + self.step.to_bytes(2, byteorder="big")
        crc = self.add_crc16(res)
        hi = (crc >> 8).to_bytes(1, byteorder="big")
        lo = (crc & 0xff).to_bytes(1, byteorder="big")
        return res + hi + lo       
 
    pass

if __name__ == '__main__':
    # 字符串转字节
    u = Uart()
    s = "01030000000A"
    sss = b'\x01\x03\x00\x00\x00\x0A\xC5\xCD'
    print(bytes.fromhex(s))
    print(bytearray.fromhex(s))
    
 
    print( u.add_crc16(bytes.fromhex(s)) )
    print("00000000000000000000000000000000000")
    print(sss[:-2])
    if u.crc16Check(sss):
        print("TRUE,...")
    else:
        print("fffffffffffff")
    
    # 数字转字节
    a = 1024
    b=a.to_bytes(2, byteorder='big') # 2个字节
    
 
    a.from_bytes(b'\x04\x00', byteorder='big')
    
    # ASCIIunpack
    data = "a"
    bytes(data, encoding='utf8')
    
    # struct 打包转字节
    ss = struct.pack('>H', 8)  # unpack
    print(ss)
    pass