Hitachi, Ltd.

Hitachi Information & Control Solutions, Ltd.

Tatsuyuki Ootani

Masahiro Shiraishi

Masakazu Ishikawa

Yasuyuki Furuta

Yutaka Uematsu

Manabu Kubota

Eiji Kobayashi

Shin Kokura

Satoru Funaki

Katsumi Yoshida

Naoya Mashiko

Akihiro Onozuka

Masamitsu Kobayashi

Takashi Umehara

Goro Hamamoto

Akira Bandou

Yuusuke Seki

Takenori Kasahara

Wataru Sasaki

Yasuhiro Kiyofuji

Yusaku Otsuka

Yu Iwasaki

Atsushi Nishioka

Shoichi Ozawa

Hisashi Terae

Akihiro Nakano

Hidechiyo Tanaka

Jouji Matsushita

Fujiya Kawawa

Syuichi Nagayama

A plant control system and communication method are capable of immediately dealing with wrong address settings created due to a human error during the execution of an opening procedure. In the plant control system, a higher-level device and a plurality of communication terminal devices are connected to each other through a communication path. Prior to the start of communication, a communication opening process of sequentially transmitting a call signal from the higher-level device to the terminal devices and acknowledging response signals therefrom is executed, which is followed by sequentially transmitting a call signal from the higher-level device to the terminal devices and receiving response signals from the terminal devices. The communication terminal devices compare addresses of the response signals returned from the other terminal devices to the higher-level device against an address set for local terminal devices. If a duplicate address exists, communication from the local terminal device is locked.

Communication device and communication method for plant control system

Main wiring including a plurality of differential transmission lines for transmitting differential signals is formed on a motherboard. Termination resistors, provided at both ends of each of the plurality of differential transmission lines, connect the plurality of differential transmission lines to each other. A plurality of daughter boards are connected in parallel to each other via the main wiring. A line characteristic impedance of each differential transmission line is higher than a termination resistance value, which is a resistance value of the termination resistor.

Control device

A signal transmission device has a multi-point wiring structure in which termination resistors are mounted on both ends of a cable, and a plurality of PCBs connected to the cable transmit a signal through the cable. The PCB of a host node includes: a connector connected to the cable; a transformer unit that is connected to the connector via a first PCB transmission line and insulates the connector; an RS 485 transceiver that is connected to the transformer unit via a second PCB transmission line and transmits the signal to the PCB of another node or receives the signal from the PCB of another node; and AC termination that is provided in at least one of the first PCB transmission line and the second PCB transmission line and suppresses resonance and antiresonance in a reflection frequency characteristic of noise.

Signal transmission device

In a control apparatus which transmits/receives data from a central processing unit via a serial transfer channel to a communication control unit, and groups/distributes data of input/output units from the communication control unit via a parallel transfer channel, the control apparatus initiates a diagnosing unit of the parallel transfer channel in response to an instruction issued from the central processing unit, and diagnosis the input/output units subsequent to the diagnosis of the transmission channel. Data input/output timing of the input/output unit is also instructed from the central processing unit, so that the central processing unit can suppress lowering of response speeds caused by the diagnoses, and can maintain the periodicity of the data input/output.

Control apparatus, control method and control program

A fault diagnosis apparatus and method capable of simultaneously detecting the fault of a multiplexer and the fault of an A/D converter and isolating and identifying causes of these faults, the multiplexer and the A/D converter being used in a multi-channel analog input/output circuit. Test-voltage values are inputted from a diagnosis-voltage input unit into the multiplexer and the A/D converter constituting an analog-signal conversion unit, the multiplexer having plural channels, the A/D converter converting outputs from the multiplexer into digital signals, the test-voltage values being different from each other for each channel of the multiplexer. Comparisons are made between the digital voltage values and the test-voltage values inputted, the digital voltage values being outputted for each channel of the multiplexer. From this comparison result, it is judged whether the multiplexer is at fault or the A/D converter is at fault.

Fault diagnosis apparatus and fault diagnosis method of multi-channel analog input/output circuit

A programmable electronic controller in which one central arithmetic processing unit and a plurality of input devices and output devices are connected by means of a parallel bus, the controller being basically configured to activate a self-diagnostic function and a diagnostic test of the input devices and the output devices with an instruction from a microprocessor of the central arithmetic processing unit; and to judge the result with the microprocessor of the central arithmetic processing unit, by using the microprocessor installed in the central arithmetic processing unit also as a processor for tests (diagnostic tests) of the self-diagnostic function of the input devices and output devices and conducting tests of the self-diagnostic function of the plurality of input devices and output devices with the central arithmetic processing unit.

Communication control system and communication control method

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Hitachi, Japan

Tatsuyuki Ootani