Transmission error detection in disaster prevention supervisory system

摘要

In a transmission reception mode the receiver sends calling data including address data for specifying a specific terminal device and causes the terminal device specified by the address data to return error detection response data including self-address data and check data at a predefined current level. When the current level of the check data in the error detection response data received by the receiver is not equal to, or within a predetermined range of, the predefined current, it is decided that an abnormality is present in the terminal device of the address specified by the calling data.