“ AT + CGPSINFO”命令适用于Socat，但不适用于PySerial

问题描述

以下Socat命令根据需要返回GPS数据：

echo 'AT+CGPSINFO' | socat - /dev/ttyUSB3,crnl

+CGPSINFO: 5100.505778,N,11404.437214,W,031120,175538.0,1076.7,0.0,348.0

OK

现在，我想使用PySerial在Python中执行相同的操作，但是出现错误。

from serial import Serial
import time

def sleep_for_x_seconds(sleep_secs=0.25):
    print(f"Sleeping for {sleep_secs} seconds...")
    time.sleep(sleep_secs)

def write_to_modem(modem,to_write,sleep=True,sleep_secs=0.25,readlines=True):
    print(f"Writing {to_write}...")
    modem.write(to_write)
    if sleep:
        sleep_for_x_seconds(sleep_secs)
    if readlines:
        print(modem.readlines())

sleep_secs = 0.25
port = "/dev/ttyUSB3"
print(f"Initializing modem on port '{port}'...")
modem = Serial()
modem.port = port
modem.timeout = 1  # How long to wait when reading lines
modem.writeTimeout = 1
sleep_for_x_seconds(sleep_secs)

print("opening modem and flushing input and output...")
modem.open()
modem.flushinput()
modem.flushOutput()
sleep_for_x_seconds(sleep_secs)

# This first command returns [b'\r\n',b'OK\r\n']
write_to_modem(modem,b"AT\r\n",sleep_secs=sleep_secs,readlines=True)

# This second command returns [b'\r\n',b'ERROR\r\n'] for some reason... why?
write_to_modem(modem,b"AT^CGPSINFO=1\r\n",readlines=True)

modem.flushinput()
modem.close()

这是运行上述程序的完整输出日志（为便于阅读，添加了换行符）：

Initializing modem on port '/dev/ttyUSB3'...
Sleeping for 0.25 seconds...

opening modem and flushing input and output...
Sleeping for 0.25 seconds...

Writing b'AT\r\n'...
Sleeping for 0.25 seconds...
[b'\r\n',b'OK\r\n']

Writing b'AT^CGPSINFO=1\r\n'...
Sleeping for 0.25 seconds...
[b'\r\n',b'ERROR\r\n']

当在Socat中运行以下命令时，为什么在运行PySerial时出现错误“ [b'\ r \ n'，b'ERROR \ r \ n']”？

echo 'AT+CGPSINFO' | socat - /dev/ttyUSB3,348.0

OK

解决方法

正如@meuh在评论中所示，我使用的是^而不是+，因此将其更改为b"AT+CGPSINFO=1\r\n"可以解决问题...