@staticmethod
def toggle_output(output_id, ramp):
    """Generate a command that toggles a single output-port.

        Toggle mode: (on->off, off->on).

        :param    int    output_id:    Output id 0..3
        :param    int    ramp:         Ramp value
        :return:    The PCK command (without address header) as text
        :rtype:    str
        """
    if output_id < 0 or output_id > 3:
        raise ValueError('Invalid output_id.')
    return 'A{:d}TA{:03d}'.format(output_id + 1, ramp)
