Python:通过串口从Velleman k8090读取数据 [英] Python: Read data via serial port from Velleman k8090
问题描述
我有一个Velleman k8090中继板,我正在尝试从中读取一些数据.我可以很好地写在板上,但是每当输出读取的数据时,我都会得到奇怪的字符,例如菱形或上下颠倒的问号.这是我的代码的一部分:
I have a Velleman k8090 Relay Board from which I am trying to read some data. I can write to the board fine, but whenever I output the read data, I get strange characters like a diamond or an upside-down question mark. Here is part of my code:
import serial
COM_PORT = 'COM4'
class Velleman8090:
def __init__(self, port=COM_PORT):
self.port = port
self.baud_rate = 19200
self.data_bits = 8
self.parity = 'N'
self.stop_bits = 1
self.flow_control = 'N'
def open_device(self):
self.talk = serial.Serial(self.port, self.baud_rate, self.data_bits, self.parity, self.stop_bits)
def firmware_version(self):
data = packet(0x71, 0x00, 0x00, 0x00)
self.talk.write(data)
print self.talk.read()
def close_device(self):
self.talk.close()
def chksum(cmd,msk,p1,p2):
return (((~(0x04 + cmd + msk + p1 + p2)) + 0x01) & 0xff)
def packet(cmd,msk,p1,p2):
return str(bytearray([0x04, cmd, msk, p1, p2, chksum(cmd, msk, p1, p2), 0x0f]))
def main():
vm8090 = Velleman8090()
vm8090.open_device()
vm8090.firmware_version()
vm8090.close_device()
为什么我会得到这些奇怪的角色?文档指出它将返回年份和星期.
Why am I getting these strange characters? The documentation states that it should return the year and the week.
经过一些搜索和故障排除后,我现在很确定它与Python代码或数据类型有关,而与硬件无关.此论坛包含一个用C语言编写的示例,该示例从董事会中读取.我得到了该示例,可以从板上正确阅读,因此我可以肯定,它与Python代码有关,与硬件本身无关.
After some searching and troubleshooting, I am now pretty sure it has something to do with the Python code or data types and not the hardware. This forum contains an example in C which reads from the board. I got that example to properly read from the board so I am fairly sure it has something to do with the Python code and not the hardware itself.
推荐答案
经过大量的努力,我终于找到了问题所在.这是一个Python编码问题.输出数据实际上已编码为我得到的奇怪字符.只需一行代码即可获得我期望的输出:
After much effort, I finally found the issue. It was a Python encoding issue. The output data was actually being encoded to the strange characters I was getting. Only one line of code was needed to get the output I was expecting:
output = self.talk.read(7)
output = output.encode('hex') #converts the strange characters to hex
print output
希望这会在将来对其他人有所帮助.
Hopefully this will help some others in the future.
这篇关于Python:通过串口从Velleman k8090读取数据的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!