The Furukawa Electric Co., Ltd.

Mazda Motor Corporation

Eiji Ichii

Hiroo Moriue

Yutaka Matsuda

Yoshikazu Nobutoki

Hiroaki Sakamoto

Hideki Kimura

Shoji Hara

Satoshi Kawai

Koji Terayama

Mitsunori Kato

Shigeki Itabashi

Akihito Yahara

Atsushi Sasaki

Hiroshi Mizoguchi

A data communication system comprising a terminal unit for generating light signals responsive to status of switches and a control unit for receiving the signals spatially propagated and controlling operation of a predetermined load, wherein switchesandare interposed between plus and minus linesandas power lines for supplying electric power from the control unit to the terminal unit, and connected in series with respective resistors Rand Rhaving different values of resistance, and the minus line is grounded in the control unitthrough resistor R. Potential of the minus line changes in response to switchesandand electronic signals indicative of the status of the switches are transmitted to the control unit separately from the light signals. Thus, even if the spatial propagation of the light signals is interrupted, the control over the operation of the load is secured.

Data communication system

When a CPU core of a node detects change of data which comes into the node from a load connected thereto on the input side, and thereby the CPU core and a transmission control circuit wake up, the node transmits a frame for waking-up to a transmission line . However, when the node receives a frame for waking-up from another node via the transmission line and thereby wakes up, the node does not transmit a frame for waking-up. Thus, an increase in traffic at the time of waking up is reduced and data transmission in a normal operation mode is started soon, so that the speed of data transmission is increased.

Multiplex communicating method

An electrical equipment module is mounted in, for example, an electrically-powered seat unit for a vehicle. Multiple wire groups ( ) comprised of wire harnesses or flat cables are led out of a module body ( ) of the electrical equipment module ( ) from different sides of the module body, thus reducing the outside diameter and thickness of each wire group so that the module body is thin and suited to be mounted in narrow layout space under a seat. By mounting, to the module body, a connector for connecting a printed circuit board ( ) in the module body to an external power supply or an external sensor and by making complicated wiring between the connector and the printed circuit board ( ) in advance in the module body, an assembling (wiring) work at the time of manufacturing the electrical equipment module is simplified.

Electrical equipment module

Basic nodes each having a communication control circuit and a CPU and I/O nodes each having a communication control circuit are interconnected via a bus. Each of the communication control circuits makes the bus active when transmitting a frame therefrom, and on judging that the bus is not active when receiving the frame, suspends the frame transmission and enters a transmission inhibited state. The basic nodes periodically transmit a frame, and when this frame is received, each I/O node cancels its transmission inhibited state and thus is restored to the state in which the frame transmission therefrom can be initiated.

Multiplex transmission method

A multiplex transmission apparatus, having a communication control circuit for carrying out transmit-receive control of a frame of data transmitted through a bus, and an output port for outputting data in frame received by the communication control circuit. The multiplex transmission apparatus is operated by a power supply voltage supplied from a power supply circuit to perform data communication with another multiplex transmission apparatus via a bus. First and second low voltage detection circuits, when detecting preset voltage values V.sub.L and V.sub.R of a power supply voltage, reset the communication control circuit and the output port. This multiplex transmission apparatus keeps the output of the output port in a normal condition despite relatively small variations in the power supply voltage (i,e., where V.sub.L .gtoreq.power supply voltage&gt;V.sub.R).

Multiple transmission apparatus

A multiplex transmission apparatus includes a communication control circuit, which monitors data output from an output port and which changes the state of the output port to a predetermined specific state when at least part of the monitored data fails to show a predetermined periodic change with respect to corresponding data previously output, and is operated by a power supply voltage applied thereto from a power circuit to carry out data communications with other multiplex transmission apparatuses. A communication IC maintains the operating state of or resets the output port and the communication control circuit of the multiplex transmission apparatus in accordance with the result of detection by a low-voltage detecting circuit, and a gate circuit inhibits the output port from being changed to the specific state by a timer IC when low voltage is detected or during sleep mode.

Multiplex transmission apparatus

A multiplex transmission system includes a number of multiplex transmission devices connected to each other via a common transmission line for transmitting frames of data. Each frame of data includes a string of bits. The number of multiplex transmission devices includes a first multiplex transmission device having a first communication controller, the first communication controller transmitting a first frame of data at predetermined intervals of time while changing a predetermined bit of data in the first frame; and a second multiplex transmission device having a second communication controller, the second communication controller transmitting a second frame of data to the first multiplex transmission device in response to one of (i) a change in input data from an external equipment, and (ii) a change in the predetermined bit of the first frame when the first frame is received by the second multiplex transmission device from the first multiplex transmission device.

Monitoring multiplex transmission system having a respective controller

A multiplex transmission apparatus includes a communication control circuit connected to a bus for successively receiving data from the bus, and the received data is output from an output port to a load via an output circuit. The successively received data is once stored in a receiving buffer and is then transferred to the output port. A port control circuit, which is connected to the output port, monitors the data transferred to the output port. When at least part of the data does not change in a predetermined manner in response to the data received immediately before, the port control circuit controls data outputted from the output port so that loads controlled according to the data from the output port are held in a safe state.

Method and apparatus for multiplex transmission

A multiplex transmission system according to this invention includes a plurality of multiplex nodes connected to one another via a common multiplex bus, for effecting data transfer between the nodes. When reception nodes correctly receive data transmitted from one of the nodes for each frame, each of the reception nodes returns an ACK signal to the multiplex bus, registers all of the nodes connected to the multiplex bus into the ACK table in response to the ACK signal, and effects the ACK management. In this case, for example, if a door FR multiplex node causes an interruption to transmit a frame while an air-conditioning unit multiplex node is retransmitting a frame, the air-conditioning unit multiplex node effects the ACK management without regarding the ACK signal for the interruption frame as an object of the updating logic of its own ACK table.

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Hiratsuka, Japan

Eiji Ichii