make device ready to join the Thread Network with a given role

        Args:
            eRoleId: a given device role id

        Returns:
            True: ready to set Thread Network parameter for joining desired Network

def joinNetwork(self, eRoleId):
        """make device ready to join the Thread Network with a given role

        Args:
            eRoleId: a given device role id

        Returns:
            True: ready to set Thread Network parameter for joining desired Network
        """
        print '%s call joinNetwork' % self.port
        print eRoleId

        self.deviceRole = eRoleId
        mode = 15
        try:
            if ModuleHelper.LeaderDutChannelFound:
                self.channel = ModuleHelper.Default_Channel

            # FIXME: when Harness call setNetworkDataRequirement()?
            # only sleep end device requires stable networkdata now
            if eRoleId == Thread_Device_Role.Leader:
                print 'join as leader'
                #rsdn
                mode = 15
                if self.AutoDUTEnable is False:
                    # set ROUTER_DOWNGRADE_THRESHOLD
                    self.__setRouterDowngradeThreshold(33)
            elif eRoleId == Thread_Device_Role.Router:
                print 'join as router'
                #rsdn
                mode = 15
                if self.AutoDUTEnable is False:
                    # set ROUTER_DOWNGRADE_THRESHOLD
                    self.__setRouterDowngradeThreshold(33)
            elif eRoleId == Thread_Device_Role.SED:
                print 'join as sleepy end device'
                #s
                mode = 4
                self.setPollingRate(self.sedPollingRate)
            elif eRoleId == Thread_Device_Role.EndDevice:
                print 'join as end device'
                #rsn
                mode = 13
            elif eRoleId == Thread_Device_Role.REED:
                print 'join as REED'
                #rsdn
                mode = 15
                # set ROUTER_UPGRADE_THRESHOLD
                self.__setRouterUpgradeThreshold(0)
            elif eRoleId == Thread_Device_Role.EndDevice_FED:
                # always remain an ED, never request to be a router
                print 'join as FED'
                #rsdn
                mode = 15
                # set ROUTER_UPGRADE_THRESHOLD
                self.__setRouterUpgradeThreshold(0)
            elif eRoleId == Thread_Device_Role.EndDevice_MED:
                print 'join as MED'
                #rsn
                mode = 13
            else:
                pass

            # set Thread device mode with a given role
            self.__setDeviceMode(mode)
            self.__setKeySwitchGuardTime(0)  #temporally
            time.sleep(0.1)
            # start OpenThreadWpan
            self.__startOpenThreadWpan()
            time.sleep(3)
            return True
        except Exception, e:
            ModuleHelper.WriteIntoDebugLogger('joinNetwork() Error: ' + str(e))