python串口库函数-python串口模块pyserial简单介绍工作实践真知分享ITp

python串⼝库函数_python串⼝模块pyserial简单介绍⼯作实践真知分享ITp。。。前⾯已经介绍过ubuntu下安装ch341的驱动程序下⾯安装python的串⼝模块,这样就直接可以将协调器发⽣送过来的所有数据,通过python串⼝读出来,然后写⼊到数据库中(可以使⽤python操作数据库的),有关数据库的远程同步(搜索mysql同步)这个以后再说.⾸先要有⼏点认识:FeaturessameclassbasedinterfaceonallsupportedplatformsaccesstotheportsettingsthroughPython2.2+propertiesportnumberingstartsatzero,noneedtoknowtheportnameintheuserprogramportstring(devicename)canbespecifiedifaccessthroughnumberingisinappropriatesupportfordifferentbytesizes,stopbits,parityandflowcontrolwithRTS/CTSand/orXon/XoffworkingwithorwithoutreceivetimeoutfilelikeAPIwith“read”and“write”(“readline”etc.alsosupported)Thefilesinthispackageare100%purePython.TheydependonnonstandardbutcommonpackagesonWindows(pywin32)andJython(JavaComm).POSIX(Linux,BSD)usesonlymodulesfromthestandardPythondistribution)Theportissetupforbinarytransmission.NoNULLbytestripping,CR-LFtranslationetc.(whicharemanytimesenabledforPOSIX.)Thismakesthismoduleuniversallyuseful.⿊体字的部分注意⼀下,特别是最后⼀项.全部是⼆进制传输.sudoeasy_installpyserial然后测试⼀下sudopython(这是为了⼀会给串⼝读写权限)>>>importserial>>>ser=serial.Serial('/dev/serial/by-id/usb-1a86_USB2.0-Serial-if00-port0')>>>serSerial(port='/dev/serial/by-id/usb-1a86_USB2.0-Serial-if00-port0',baudrate=9600,bytesize=8,parity='N',stopbits=1,timeout=None,xonxoff=False,rtscts=False,dsrdtr=False)>>>ser.timeout=1>>>serSerial(port='/dev/serial/by-id/usb-1a86_USB2.0-Serial-if00-port0',baudrate=9600,bytesize=8,parity='N',stopbits=1,timeout=1,xonxoff=False,rtscts=False,dsrdtr=False)有时候如果你使⽤/dev/ttyUSB0⾏不通的话,就直接使⽤/dev/serial/by-id/usb-1a86_USB2.0-Serial-if00-port0timeout=None,#setatimeoutvalue,Noneforwaitingforever上⾯timeout的意思是,如果是none,那么程序永远会死在这⾥.⼀直等待timeout=0#non-blockingmode(returnimmediatelyonread)timeout=0:⾮阻塞形式(读完之后就返回,费时的io操作,就直接交给后台处理了)

timeout=x#settimeouttoxseconds(floatallowed)超时时间⼀到,程序就是继续执⾏————————–没错我是分割线–开始————————————⼩知识:读写串⾏⼝时，既可以同步执⾏，也可以重叠(异步)执⾏。在同步执⾏时，函数直到操作完成后才返回。这意味着在同步执⾏时线程会被阻塞，从⽽导致效率下降。在重叠执⾏时，即使操作还未完成，调⽤的函数也会⽴即返回。费时的I/O操作在后台进⾏，这样线程就可以⼲别的事情。例如，线程可以在不同的句柄上同时执⾏I/O操作，甚⾄可以在同⼀句柄上同时进⾏读写操作。”重叠”⼀词的含义就在于此。阻塞的定义：对于read，block指当串⼝输⼊缓冲区没有数据的时候，read函数将会阻塞在这⾥，⼀直到串⼝输⼊缓冲区中有数据可读取，read读到了需要的字节数之后，返回值为读到的字节数；对于write，block指当串⼝输出缓冲区满，或剩下的空间⼩于将要写⼊的字节数，则write将阻塞，⼀直到串⼝输出缓冲区中剩下的空间⼤于等于将要写⼊的字节数，执⾏写⼊操作，返回写⼊的字节数。⾮阻塞的定义：对于read，noblock指当串⼝输⼊缓冲区没有数据的时候，read函数⽴即返回，返回值为0。对于write，noblock指当串⼝输出缓冲区满，或剩下的空间⼩于将要写⼊的字节数，则write将进⾏写操作，写⼊当前串⼝输出缓冲区剩下空间允许的字节数，然后返回写⼊的字节数。—————————-没错我是分割线–结束———————————-Becarefullywhenusing“readline”.Dospecifyatimeoutwhenopeningtheserialportotherwiseitcouldblockforeverifnonewlinecharacterisreceived.Alsonotethat“readlines”onlyworkswithatimeout.“readlines”dependsonhavingatimeoutandinterpretsthatasEOF(endoffile).Itraisesanexceptioniftheportisnotopenedcorrectly.ParametersfortheSerialclassser=serial.Serial(port=None,#numberofdevice,numberingstartsat#zero.ifeverythingfails,theuser#canspecifyadevicestring,note#thatthisisn'tportableanymore#ifnoportisspecifiedanunconfigured#anclosedserialportobjectiscreatedbaudrate=9600,#baudratebytesize=EIGHTBITS,#numberofdatabitsparity=PARITY_NONE,#enableparitycheckingstopbits=STOPBITS_ONE,#numberofstopbitstimeout=None,#setatimeoutvalue,Noneforwaitingforeverxonxoff=0,#enablesoftwareflowcontrolrtscts=0,#enableRTS/CTSflowcontrol

interCharTimeout=None#Inter-charactertimeout,Nonetodisable)MethodsofSerialinstancesopen()#openportclose()#closeportimmediatelysetBaudrate(baudrate)#changebaudrateonanopenportinWaiting()#returnthenumberofcharsinthereceivebufferread(size=1)#read"size"characterswrite(s)#writethestringstotheportflushInput()#flushinputbuffer,discardingallit'scontentsflushOutput()#flushoutputbuffer,abortoutputsendBreak()#sendbreakconditionsetRTS(level=1)#setRTSlinetospecifiedlogiclevelsetDTR(level=1)#setDTRlinetospecifiedlogiclevelgetCTS()#returnthestateoftheCTSlinegetDSR()#returnthestateoftheDSRlinegetRI()#returnthestateoftheRIlinegetCD()#returnthestateoftheCDlineAttributesofSerialinstancesreadonlyportstr#devicenameBAUDRATES#listofvalidbaudratesBYTESIZES#listofvalidbytesizesPARITIES#listofvalidparitiesSTOPBITS#listofvalidstopbitwidthsNewvaluescanbeassignedtothefollowingattributes,theportwillbereconfigured,evenifit’sopenedatthattime:(即使是打开的情况下也会重新配置liub)port#portname/numberassetbytheuserbaudrate#currentbaudratesettingbytesize#bytesizeinbitsparity#paritysettingstopbits#stopbitwith(1,2)timeout#timeoutsettingxonxoff#ifXon/Xoffflowcontrolisenabled

rtscts#ifhardwareflowcontrolisenabled居然还有这么多好东西,看看下⾯:TCP/IP–serialbridgeThisprogramopensaTCP/IPport.Whenaconnectionismadetothatport(e.g.withtelnet)itforwardsalldatatotheserialportandviceversa.Thisexampleonlyexportsaraws