Python SerialException：设备报告已准备好读取，但未返回数据（设备已断开连接？）

Question

我有两个Raspberry Pi使用串行端口和一对XRF无线电相互发送数据。通常它们工作正常，完整的程序循环多次，但每隔一段时间就会有一个程序停止，错误如下：

File "BaseListener.py, line 56, in <module>
recieved=serialport.read()
File "/usr/lib/python2.7/dist-packages.serial/serialposix.py", line 465, in read raise SerialException('Device reports readiness to read but returned no data (device disconnected?)')
serial.serialutil.SerialException: device reports readiness to read but returned no data (device disconnected?)

我的代码是：

import sys
import serial
import time
import datetime

date = datetime.date.today()
strdate = str(date)
serialport=serial.Serial("/dev/ttyAMA0", 9600, timeout=0.25)
command=''
loop=0
recieving=False
recieving2=False
format = "%Y-%m-%d %H:%M:%S"

while True:
    while (recieving==False):
        loop = 0
        command=''
        while (loop<30):
            recieved = serialport.read()
            command = command + recieved
            loop = loop+1
        if "DR" in command:
            print"DR Recieved"
            serialport.write("BSAKAKBS")
            recieving=True
    while (recieving ==True):
        loop = 0
        command=''
        while (loop<30):
            recieved = serialport.read()
            command = command + recieved
            loop = loop+1
        sensorid = command[0:2]
        print ("Command: "+command)
        print ("SensorID: "+sensorid)
        graintemp = command[2:6]
        print "GrainTemp Recieved"
        serialport.write("BS"+graintemp+"BS")
        print (str(graintemp))
        loop = 0
        command=''
        while (loop<30):
            recieved = serialport.read()
            command = command + recieved
            loop = loop+1
        if sensorid in command:
            if "AK" in command:
                print "GrainTemp AK recieved"
                serialport.write("BSAKAKBS")
                recieving2=True
                while (recieving2==True):
                    loop=0
                    command=''
                    while (loop<30):
                        recieved = serialport.read()
                        command = command + recieved
                        loop = loop+1
                    print ("Command: "+command)
                    airtemp = command[2:6]
                    print "AirTemp Signal Recieved"
                    serialport.write("BS"+airtemp+"BS")
                    print ("AirTemp: "+str(airtemp))
                    loop = 0
                    command=''
                    while (loop<30):
                        recieved = serialport.read()
                        command = command + recieved
                        loop = loop+1
                    if sensorid in command: 
                        if "AK" in command:
                            print ("AK command: ")
                            print "AirTemp AK Recieved"
                            serialport.write("BSAKAKBS")
                            #File Storage
                            today = datetime.datetime.today()
                            fulltime = today.strftime(format)
                            strtime = str(fulltime)
                            graindata = fulltime + ' ' + graintemp +'\n'
                            airdata = fulltime + ' ' + airtemp +'\n'
                            file = open(sensorid+"Graindata.dat", "a")
                            file.write(graindata)
                            file.close
                            file = open(sensorid+"Airdata.dat", "a")
                            file.write(airdata)
                            file.close
                            recieving=False
                            recieving2=False
                            loop=0
                            command=''
                            graindata=''
                            airdata=''
                            graintemp=0
                            airtemp=0
                            print "Files stored. Restarting"
                        else:
                            print ("IC Command: ")
                            print "Airtemp IC Recieved"
                            serialport.write("BSICICBS")
                            loop = 0
                            command=''
                    else:
                        print "Airtemp ID IC Recieved"
                        serialport.write("BSICICBS")
                        loop = 0
                        command=''
            else:
                serialport.write("BSICICBS")
                print "Graintemp IC Recieved"
                loop = 0
                command=''
        else:
            serialport.write("BSICICBS")
            print "Graintemp ID IC Recieved"
            loop = 0
            command=''

另一个Pi上的代码类似（如果需要，我可以提供）。

从我在网上发现的情况来看，试图读取串行端口是有问题的，但它是空的。我已经看到使用try-and-catch异常的建议，但我不确定这是否有用（或者知道如何真正做到这一点）。我需要代码在没有任何用户干扰的情况下连续运行。如果串行端口是空的，那么AK和IC循环应该会接收到与错误传输相同的数据，所以我只需要它传递空值。 有办法吗？