Fuji Electric Co., Ltd.

Eiichi Nabeta

Takashi Yoshida

Kenji Asanuma

Noboru Kanzaki

Takeshi Yasuhara

Takahiro Suzuki

An optical-signal/electric-signal converting device communications system for a communications system that establishes communications using electric and optical signals. The converting device converts an electric transmission signal into an optical transmission signal and an optical transmission signal into an electric transmission signal. The converting device includes an electric signal receiving circuit for receiving the electric transmission signal transmitted from the host computer of the communications system through an electric transmission line, and a modulating circuit for modulating the electric signal sent from the electric signal receiving circuit into a pulse signal having pulses of a smaller width. The converting device also includes an optical signal receiving circuit for receiving the optical transmission signal from the optical transmission line of the system and converting the received signal into an electric signal using a light-receiving element, and a demodulation circuit for demodulating the electric signal received from the optical signal receiving circuit into a pulse signal having pulses of a larger width.

Optical-signal/electric-signal converting device

An optical communications device is disclosed which is equipped with a transmission unit adapted to send binary-coded electrical pulse signals to another optical communications device in the form of optical pulse signals. The transmission unit includes a modulator for producing an electrical pulse signal of a narrow pulse width only at each of rising and falling edges in the binary-coded electrical pulse signals and an electro-optic converter for converting the electrical pulse signal of a narrow pulse width into an optical pulse signal of a narrow pulse signal. As an alternative, the transmission unit includes a modulator which produces an electrical pulse signal of a narrow pulse width for each bit in the binary-coded electrical pulse signals only when it is at a high level and an electro-optic converter which converts the electrical pulse signal of a narrow pulse width into an optical pulse signal of a narrow pulse width.

Optical communications device

An improved field instrumentation system employing optical multiplex transmission in which data from a plurality of field devices, including both sensors and controllers, are transmitted through an optical distributor, such as a star coupler, to a master processor at a control panel location as well as to other field devices. The optical distributor branches and couples in a ratio of N:N, the data which are transmitted bidirectionally through the various optical transmission paths connected to the field devices to form the basis of a control loop located in the field. A submaster processor, located in the field and coupled to the optical distributor, is automatically substituted for the master processor in the event that the master processor is disabled. The overall reliability of this system is thereby markedly improved.

Field instrumentation system

Disclosed is a measurement apparatus for measuring physical quantity, such as temperature, pressure etc., and providing corresponding measuremnt data suitable for transmission to a remote central location. The physical quantity being measured is first converted to a frequency signal, either directly by an appropriate transducer or by a combination of an appropriate transducer and appropriate converter. Counters are then used to convert the frequency signal to a corresponding digital quantity. An appropriately programmed digital processor is then used to perform processing operations on the digital quantity to derive the measurement data. In one embodiment, the apparatus includes an optical transceiver for converting the measurement data into corresponding optical signals for transmission via an optical fiber to a central processor. The optical transmission system between the measurement apparatus and the central processor includes provisions for facilitating the detection and diagnosis of failures in the optical components of the system. In another embodiment the measurement data is converted to corresponding current signals for transmission via a conducter to a remote central location.

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Kawasaki, Japan

Eiichi Nabeta