    def do_set_workdir(self, args):
        """Set the working directory.

        The working directory is used to load and save known devices
        to improve startup times. During startup the application
        loads and saves a file `insteon_plm_device_info.dat`. This file
        is saved in the working directory.

        The working directory has no default value. If the working directory is
        not set, the `insteon_plm_device_info.dat` file is not loaded or saved.

        Usage:
            set_workdir workdir
        Arguments:
            workdir: Required - Working directory to load and save devie list
        """
        params = args.split()
        workdir = None

        try:
            workdir = params[0]
        except IndexError:
            _LOGGING.error('Device name required.')
            self.do_help('set_workdir')

        if workdir:
            self.tools.workdir = workdir