An apparatus and a method for a walking aid are disclosed. Conveying device for conveying a flat material in a direction of conveyance between the blades. An inconsistency detecting unit detects an inconsistent data group which cannot be consistent by scanning a data set aggregated by the data aggregating unit. The outer width of the horizontal links is at least 30% greater than the outer width of the vertical links. Also disclosed are a communication system and a controlling method for varying between such two modes a standby time that must elapse before a command can be accepted following a bus reset, one mode permitting communication between the reserved target devices, the other mode inhibiting such intercommunication. The grounding plate connects to the tongues of the USB socket to ground the system.