Data transmission apparatus and data transmission system

Abstract

A data transmission apparatus (10) for transmitting a data signal in accordance with a predetermined protocol in one direction within a ring network of a plurality of data transmission apparatuses includes: signal determination means (11) for determining a presence or absence of a data signal from an immediately upstream data transmission apparatus (10) in the ring network based on an amplitude of the data signal; and stopping means for stopping transmission of the data signal to an immediately downstream data transmission apparatus (10) if the signal determination means (11) determines that there is no incoming data signal. The data signal is a signal obtained by modulating an amplitude component of an electrical signal of a predetermined frequency. Thus, a data transmission apparatus is provided which can quickly detect a momentary power interruption in a data transmission system composed of data transmission apparatuses interconnected in a ring fashion.

Description

technical field [0001] The present invention relates to a data transmission device, more specifically, relates to the invention of a data transmission device which uses multiple sets to form a ring network, and transmits electrical signals to one direction in the ring network according to a prescribed communication protocol. Background technique [0002] In recent years, large-capacity and high-speed communication is required to transmit and image information on the Internet such as car navigation systems and ITS (Intelligent Transport Systems), or in spaces such as the interior of automobiles. Research on communication methods for transmitting digital data such as digitized image and audio data or computer data is being conducted extensively, and networks that can transmit digital data even in spaces such as automobiles are being introduced in earnest. The goal of this in-vehicle network is, for example, to form a ring-type LAN in one direction by connecting multiple nodes ...

AI Technical Summary

Problems solved by technology

Therefore, in the past, when a failure continued for about 100 msec, the CPU 103 judged that a failure was caused by momentary power failure or the like.

[0034] However, when it takes 100 msec for one data transfer device 100 to detect the momentary power off, for example, the time required for all 64 data transfer devices 100 to detect the momentary power off may reach 6.4 sec.

Therefore, in the conventional detection method for momentary power interruption, it takes a very long time from the moment the momentary power interruption occurs to the restart operation (for example, refer to International Publication No. 02 / 30078).

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