File content as of revision 4:92539904a4ad:

#!/usr/bin/python -tt                       # tt: detect mixed space/tab.
#---copyright-----------------------------------#-------------------------------
#   licensed for personal and academic use.
#   commercial use must be approved by the account-holder of
#   gated.clock@gmail.com
#-------imports---------------------------------#-------------------------------
import serial                   # serial over USB.
#=======class===================================#===============================
if (1):
    class mmUSBserial():            # USB class.
#-----------------------------------------------#-------------------------------
                        # constructor.
      def __init__(self, idVendor, idProduct):      

        self.__idVendor  = idVendor     # promote to object scope.
        self.__idProduct = idProduct    # promote to object scope.

        openSuccess = 1
        self.__serialPort = serial.Serial()
        self.__serialPort.baudrate = 9600

        for portIndex in range(7, -1, -1):
          portString = "/dev/ttyACM" + "{}".format(portIndex)
          self.__serialPort.port = portString
          try:
            self.__serialPort.open()
          except:
            print("failed to open port {}.").format(portString)
            openSuccess = 0

          if (openSuccess): break
          openSuccess = 1

        if (openSuccess): print("successfully opened port {}.").format(portString)
        else:             print("could not open any port.")
#-----------------------------------------------#-------------------------------  
      def __del__(self):                    # destructor.
        self.__serialPort.close()
        print "object destroyed."
#-----------------------------------------------#-------------------------------
      def write(self,toWrite):      # write a string.
            nowWrite = toWrite[:7]
        nowWrite = nowWrite + "$"
        self.__serialPort.write(nowWrite)
        return(nowWrite)
#-----------------------------------------------#-------------------------------
      def read(self):           # read a string.
        gotRead = self.__serialPort.read(8)
        return(gotRead)
#-----------------------------------------------#-------------------------------
#===============================================#===============================