@property<EOL><INDENT>def controller(self):<DEDENT>
return self._controller<EOL>
Information about the controller.

        If no information about the controller is received, the return value
        is :obj:`None`.

        If information about the controller is known after :ref:`cnfinfo` was
        received, you can access these values:

        .. code:: python

            >>> communication.controller.firmware_version
            (5, 2)
            >>> communication.controller.firmware_version.major
            5
            >>> communication.controller.firmware_version.minor
            2
            >>> communication.controller.api_version
            4