Hitachi, Ltd.

Hitachi Software Engineering Company, Ltd.

Hiroyuki Wada

Susumu Nakayashiki

Yoshinori Bekki

Hisashi Matsumura

Jiro Kashio

Kazuko Iwatsuki

Toyokazu Hashimoto

Masahiko Kida

Yoshihito Sako

Mitsuhiro Yamaga

Takeshi Harakawa

Masato Hirai

Osamu Ebina

Kenichiro Orita

Fumiaki Matsuura

Hiroshi Nakase

Masahiro Fuse

Ihei Kajiya

An end node for which sending and receiving are controlled by a hub is directly connected and used. When another end node is directly connected to the PMD control unit,, the input control signal processor,of the signal processor,receives a receiving state signal indicating the state of a tone signal which is outputted from the PMD control unit,and received from another end node, converts it to a receiving state signal indicating the state of a tone signal from the hub which has the same meaning as it, and transfers it to the MAC/PMI control unit

Lan connection apparatus and method thereof

An end node for which sending and receiving are controlled by a hub is directly connected and used. When another end node is directly connected to the PMD control unit 2, the input control signal processor 11 of the signal processor 1 receives a receiving state signal indicating the state of a tone signal which is outputted from the PMD control unit 2 and received from another end node, converts it to a receiving state signal indicating the state of a tone signal from the hub which has the same meaning as it, and transfers it to the MAC/PMI control unit 14.

LAN adaptor system for judging a port type from among a plurality of

A line concentrator used in a ring network system which has line concentrators for accommodating ring lobes, and a ring trunk cable connecting adjacent line concentrators, wherein a signal transmitted from an upstream line concentrator is sent via the ring trunk cable to the ring lobes of an immediately downstream line concentrator. The line concentrator is provided with a circuit for regenerating a signal on the ring trunk cable received by the line concentrator, and repeating and sending the regenerated signal to the ring lobes.

Ring line concentrator

In a LAN interconnecting apparatus having two transmitting and receiving sections connected to respective LANs, each of the transmitting and receiving sections can be set in either a first or a second operation mode by setting a register. The transmitting and receiving section copies and transfers relayed information frames in the first operation mode, but it does not in the second operation mode. The apparatus makes a unidirectional LAN interconnecting apparatus when one of the transmitting and receiving sections is set in the first operation mode and the other in the second operation mode, while it makes a bidirectional one when both of the transmitting and receiving sections are set in the first operation mode.

Operation mode settable LAN interconnecting apparatus

A method for performing a duplicated address test used for a network including a first ring transmission line, a second ring transmission line having a signal transmission direction opposite to that of the first ring transmission line, and a plurality of stations connected to at least one of these ring transmission lines. Each of these stations has a flag DAC representing whether or not the duplicated address test is performed, and some of the plural stations constitute a plurality of control nodes having a configuration function of the network. The flag DAC of each of the stations is reset at a time instant when a power source of this station is turned on, and also when any of the control nodes receives the sent out configuration control frame. Each of the stations having the reset flags DAC sents out the duplicated address test frame to either the first or second transmission line to which the station is connected when a token frame to control a transmission right is captured. When another station having the same address as that of a source station receives the test frame, a discriminator indicative of an address duplication is added to this test frame.

Method and apparatus for testing station address in network

In a ring network system including two transmission lines transmitting a signal in directions opposite to each other, and a plurality of line concentrators connected in the form of a loop by the two transmission lines and each accommodating a plurality of terminal stations connected to one of the two transmission lines, a signal detecting unit and a terminating circuit are disposed in each of the line concentrators on the signal output side of each of the transmission lines so as to be connectable to and disconnectable from the transmission lines, so that, when the signal detecting unit in one of the line concentrators is connected to the associated transmission line, the transmission line is disconnected in the line concentrator, and the terminating circuit is connected to the downstream segment of the disconnected transmission line.

Ring network configuration

In a ring communications system including a plurality of line concentrators that are connected in the form of a ring, the line concentrators are connected together via a main ring, and the terminal stations connected to the line concentrators are connected to the main ring via ring subsidiaries. The main ring and the ring subsidiaries are connected together via ring connection switches that so work as to connect or disconnect the main ring and the ring subsidiaries. The ring connection switch is so constructed as to maintain the connected condition even when the power source of the line concentrator is in the turned-off state.

Ring configuration of line concentrators

A station diagnosis method in a communications network system including a closed ring transmission line and a plurality of data stations which can be connected to the ring transmission line by a plurality of line concentrators disposed in the ring transmission line wherein an internal ring transmission line is formed in the line concentrators so that the operation states of the line concentrators are diagnosed by transmitting diagnosis data through the internal ring transmission line.

Network system diagnosis system

This invention relates to a loop transmission system which has a plurality of stations connected to a loop transmission path to transmit data among the stations. In the transmission frame to be sent out from the sending station, specific information is included for identifying each frame and this information is held in the sending station. When the transmission frame returns to the sending station after being transmitted through the loop transmission path, the specific information in the frame is received and compared with the information held in the station and, if they coincide, it is decided that the transmission frame has been correctly received by the intended receiving station.

Data transmission system adapted to facilitate detection of safe receipt

A loop transmission system including a plurality of stations connected in series in a looped transmission line to transfer data among the stations, wherein the stations include a supervising station and at least one terminal station and the transmission line is duplicated so that when a fault occurs in currently used one of the transmission lines, the other transmission line which has been used as a spare is used for transmission of data, while the supervising station sends out a specific signal to the spare transmission line and the terminal stations each determines one of the transmission lines through which the specific signal is detected, as the spare.

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Hadano, Japan

Hiroyuki Wada