| 摘要 |
PURPOSE:To make the central monitoring device quickly informed of an occurrence of abnormality in a container by transmission from the related terminal by a method wherein each of signals requesting monitoring from the central monitoring device is assigned a number and a request signal assigned one such specific number is followed by setting of a time period allowed for the calling from the terminal concerned. CONSTITUTION:Ordinary polling is executed through a procedure that a central monitoring device transmits a signal requesting monitoring irregularly to each of terminals; a terminal, after receiving one such signal referring to a number assigned to the terminal, transmits in response thereto data on the operation of the refrigeration unit to the central monitoring device. In the case of an elapse of a specified time the central monitoring device transmits a request signal referring to the assigned number and follows the signal with setting of a time period allowed for the calling from the terminal concerned. The terminal of a container in which something unusual has occurred, upon receipt of a request signal referring to the assigned number, transmits the details of the abnormality to the central monitoring device within a set period of calling time (e.g. three seconds) which follows the request signal. This method enables taking a measure quickly in case of abnormality. |
