A method for automatically updating software executed by an electronic device is disclosed herein. Further, a signal can be detected based on the level slice system and detection delay time can be reduced by using a mark position form having a large detection margin as an information recording system of the header field. Each designated location in the installation plan includes an associated point name, each wireless device is configured to transmit a message indicating itself as the source of the message, and each wireless communication device is installed proximate to its designated location.