Python：与 USB 转串口转换器的串口通信失败

Question

我正在尝试编写一个代码，使用 USB 转串行转换器与串行接口通信。我运行在 Ubuntu 12.04 OS 上设置我的代码。我已经连接了设备，看起来它被系统识别了，因为 lsusb 的输出给我：

Bus 002 Device 003: ID 9710:7840 MosChip Semiconductor MCS7820/MCS7840 2/4 port serial adapter

和 dmesg 命令报告：

Tue Apr 18 15:22:07 2017] usb 2-2: new high-speed USB device number 3 using ehci_hcd
[Tue Apr 18 15:22:07 2017] usbcore: registered new interface driver usbserial
[Tue Apr 18 15:22:07 2017] USB Serial support registered for generic
[Tue Apr 18 15:22:07 2017] usbcore: registered new interface driver usbserial_generic
[Tue Apr 18 15:22:07 2017] usbserial: USB Serial Driver core
[Tue Apr 18 15:22:07 2017] USB Serial support registered for Moschip 7840/7820 USB Serial Driver*
[Tue Apr 18 15:22:07 2017] mos7840: 1.3.2:Moschip 7840/7820 USB Serial Driver
[Tue Apr 18 15:22:07 2017] mos7840 2-2:1.0: Moschip 7840/7820 USB Serial Driver converter detected
[Tue Apr 18 15:22:07 2017] usb 2-2: Moschip 7840/7820 USB Serial Driver converter now attached to ttyUSB0
[Tue Apr 18 15:22:07 2017] usb 2-2: Moschip 7840/7820 USB Serial Driver converter now attached to ttyUSB1
[Tue Apr 18 15:22:07 2017] usb 2-2: Moschip 7840/7820 USB Serial Driver converter now attached to ttyUSB2
[Tue Apr 18 15:22:07 2017] usb 2-2: Moschip 7840/7820 USB Serial Driver converter now attached to ttyUSB3
[Tue Apr 18 15:22:07 2017] usbcore: registered new interface driver mos7840

然而，当我尝试运行我的代码时，我没有从对方那里得到预期的答案。我运行ning 的代码在这里：

class RTSSerial(object):

    def __init__(self,serialID, baud):
        self.serialID = serialID
        self.baud = baud
        try:
            self.serDevice = serial.Serial(self.serialID, 
                                           baudrate = self.baud,
                                           parity = serial.PARITY_NONE,
                                           stopbits = serial.STOPBITS_ONE,
                                           bytesize = serial.EIGHTBITS)
            self.serDevice.flushInput()
            self.serDevice.flushOutput()
        except Exception as e:
            print 'Got the following exception: ', e

    def read(self):        
        try:
            inWaiting = self.serDevice.inWaiting()
        except:            
            if os.path.exists(self.serialID):
                self.serDevice = serial.Serial(self.serialID,self.baud)
            inWaiting = 0

        try:
            rec = ''
            if (inWaiting > 0):
                rec = self.serDevice.read(inWaiting)
                #Convert string message into list of integers        
            message = [ord(x) for x in rec]        
        except Exception as e:
            message = []
            print 'Got the following exception: ', e

        return message

    #Function to write to serial
    #message should be a list. Then the function converts it into a string
    def write(self, message):      
        try:
            #Convert message into string
            messageToSend = "".join(chr(x) for x in message)        
            errCode = self.serDevice.write(messageToSend)
        except Exception as e:
            errCode = 0
            print 'Got the following exception: ', e

        return errCode

ser = RTSSerial('/dev/ttyUSB0', 9600)    
mess = [0x7e, 0xa, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x4d, 0x8a]
ser.write(mess)
time.sleep(1)
reply = ser.read()

我期待这样的回复：

0x7E 0x04 0x00 CRC1 CRC2

但我得到：

0x7e 0xd 0xa 0x43 0x20 0x69 0x6e 0x74 0x65 0x72 0x70 0x3a 0x20 0x73 0x79 0x6e 0x74 0x61 0x78 0x20 0x65 0x72 0x72 0x6f 0x72 0x2e 0xd 0xa 0x2d 0x3e 0x20 0x3f 0x4d 0xd 0xa 0x43 0x20 0x69 0x6e 0x74 0x65 0x72 0x70 0x3a 0x20 0x74 0x6f 0x6b 0x65 0x6e 0x20 0x27 0x10 0x27 0x20 0x6e 0x6f 0x74 0x20 0x72 0x65 0x63 0x6f 0x67 0x6e 0x69 0x7a 0x65 0x64 0x2e 0xd 0xa 0x2d 0x3e 0x20

我在这里忽略了什么吗？提前致谢！

Answer 1

如果您以 ASCII 而不是十六进制查看该结果，您将得到：

~
C interp: syntax error.
-> ?M
C interp: token '' not recognized.
->

（引号中的标记是十六进制 0x10，您要发送的字符之一。）因此，您的串行接收工作正常 - 您只是没有得到预期的结果。看起来其他系统是在文本提示下，并不期待您发送的二进制数据包。可能需要先发送一些命令，才能使其进入正确的模式。

Python：与 USB 转串口转换器的串口通信失败

Python: serial communication with USB to serial converter failing

python

usbserial

ubuntu-12.04