Question

我尝试从设备中读取每2秒1到3行文本的行到串行打印机，使用pyserial读取该设备的串行输出。

首先，我使用minicom获取输出样本：当我用hax-reader（linux中的ghex）打开它时，我看到行的每一端都有十六进制值x0A。

当我使用pyserial（版本3.2.1）逐字节捕获输出时：

print(self.ser.read())

一行末尾的输出是

B '\ r'

B '\ n'

每次一行结束（为什么两个字符？）

我试图定义一个read_line（）函数：

import serial  

def read_line(self):
        line = []
        print("start read_line")
        while True:
            print("read_line_loop")
            for c in self.ser.read():
                line.append(c)
                print("appended")
                if c == b'\x0A':
                    print("stop condition")
                    print("Line: " + line)
                    line = []
                    break

循环按预期输入，但从不满足条件c == b'\ x0A'。显示的消息是“read_line_loop”，每隔几秒就会出现几次 “附加”，但从不“停止条件”。

有什么想法吗？

Answer 1

Ending a line with \r\n (carriage return, line feed) is the normal Windows (and typewriter) method to end a line. Translated in Hex these signs are '\x0D' and '\x0A'. Why it is not found I cannot tell you. But as you are reading lines, I would use the readline method of the serial port. As your line is ending with \n it should work nicely. You only get a problem, when your line is not ending with \n, but with something else.

Answer 2

One approach would be to output c to see what it actually is. c is likely something different than what you think.

Another approach could be to use the built-in readline method, which uses newline as it de(http://pyserial.readthedocs.io/en/latest/shortintro.html#readline).

如何在串行设备的字节流中找到EOL（行尾）

2 个答案: