read and stock various data from various usb devices in python
我是 python 的初学者，我正在尝试从通过 USB 集线器连接到计算机的多个传感器(湿度、温度、压力传感器......)读取数据。我的主要目标是每五分钟记录一次这些传感器的不同值，然后将其存储起来进行分析。
我有我的传感器(来自 Hygrosens Instruments)的所有数据表和手册，我知道它们是如何工作的以及它们发送什么样的数据。但我不知道如何阅读它们。下面是我尝试过的，使用 pyserial.
1 2 3 4 5 6 7 8 9 10 | import serial #import the serial library from time import sleep #import the sleep command from the time library import binascii output_file = open('hygro.txt', 'w') #create a file and allow you to write in it only. The name of this file is hygro.txt ser = serial.Serial("/dev/tty.usbserial-A400DUTI", 9600) #load into a variable 'ser' the information about the usb you are listening. /dev/tty.usbserial.... is the port after plugging in the hygrometer, 9600 is for bauds, it can be diminished count = 0 while 1: read_byte = ser.read(size=1) |
所以现在我想找到数据行的结尾，因为我需要的测量信息在以"V"开头的行中，如果我的传感器的数据表，它说一行结束by ，所以我想一次读取一个字节并查找'<'，然后是'c'，然后是'r'，然后是'>'。所以我想这样做：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | while 1: read_byte = ser.read(size=8) #read a byte read_byte_hexa =binascii.hexlify(read_byte) #convert the byte into hexadecimal trad_hexa = int(read_byte_hexa , 16) #convert the hexadecimal into an int in purpose to compare it with another int trad_firstcrchar = int('3c' , 16) #convert the hexadecimal of the '<' into a int to compare it with the first byte if (trad_hexa == trad_firstcrchar ): #compare the first byte with the '<' read_byte = ser.read(size=1) #read the next byte (I am not sure if that really works) read_byte_hexa =binascii.hexlify(read_byte)# from now I am doing the same thing as before trad_hexa = int(read_byte_hexa , 16) trad_scdcrchar = int('63' , 16) print(trad_hexa, end='/')# this just show me if it gets in the condition print(trad_scdcrchar) if (trad_hexa == trad_scdcrchar ): read_byte = ser.read(size=1) #read the next byte read_byte_hexa =binascii.hexlify(read_byte) trad_hexa = int(read_byte_hexa , 16) trad_thirdcrchar = int('72' , 16) print(trad_hexa, end='///') print(trad_thirdcrchar) if (trad_hexa == trad_thirdcrchar ): read_byte = ser.read(size=1) #read the next byte read_byte_hexa =binascii.hexlify(read_byte) trad_hexa = int(read_byte_hexa , 16) trad_fourthcrchar = int('3e' , 16) print(trad_hexa, end='////') print(trad_fourthcrchar) if (trad_hexa == trad_fourthcrchar ): print ('end of the line') |
但我不确定它是否有效，我的意思是我认为它没有时间读取第二个字节，我正在读取的第二个字节，它不完全是第二个字节。所以这就是我想使用缓冲区的原因，但我真的不明白我该怎么做。我要去寻找它，但如果有人知道一种更简单的方法来做我想做的事，我已经准备好尝试了！
谢谢
您似乎认为该传感器的通信协议的行尾字符是 4 个不同的字符：
由于协议是结构化的，因此您可以通过逐行读取传感器的数据来大大简化您的代码。以下内容可帮助您入门：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | import time def parse_info_line(line): # implement to your own liking logical_channel, physical_probe, hardware_id, crc = [line[index:index+2] for index in (1, 3, 5, 19)] serialno = line[7:19] return physical_probe def parse_value_line(line): channel, crc = [line[ind:ind+2] for ind in (1,7)] encoded_temp = line[3:7] return twos_comp(int(encoded_temp, 16), 16)/100. def twos_comp(val, bits): """compute the 2's compliment of int value `val`""" if (val & (1 << (bits - 1))) != 0: # if sign bit is set e.g., 8bit: 128-255 val = val - (1 << bits) # compute negative value return val # return positive value as is def listen_on_serial(ser): ser.readline() # do nothing with the first line: you have no idea when you start listening to the data broadcast from the sensor while True: line = ser.readline() try: first_char = line[0] except IndexError: # got no data from sensor break else: if first_char == '@': # begins a new sensor record in_record = True elif first_char == '$': in_record = False elif first_char == 'I': parse_info_line(line) elif first_char == 'V': print(parse_value_line(line)) else: print("Unexpected character at the start of the line:\ {}".format(line)) time.sleep(2) |
作为测试，以下代码摘录模拟传感器发送一些数据(以行分隔，使用回车作为行尾标记)，这些数据是我从您链接到的 pdf 中复制的 (FAQ_terminalfenster_E. pdf).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | >>> import serial >>> import io >>> >>> ser = serial.serial_for_url('loop://', timeout=1) >>> serio = io.TextIOWrapper(io.BufferedRWPair(ser, ser), newline='\ ', line_buffering=True) >>> serio.write(u'A1A0\ ' # simulation of starting to listen halfway between 2 records ... '$\ ' # marks the end of the previous record ... '@\ ' # marks the start of a new sensor record ... 'I0101010000000000001B\ ' # info about a sensor's probe ... 'V0109470D\ ' # data matching that probe ... 'I0202010000000000002B\ ' # other probe, same sensor ... 'V021BB55C\ ') # data corresponding with 2nd probe 73L >>> >>> listen_on_serial(serio) 23.75 70.93 >>> |
请注意，当行尾字符不是