JPS5916452B2 - Optical bus network system - Google Patents

Abstract

PURPOSE:To improve the reliability of the system and to perform signal transmission in high speed with a very simple constitution, by constitution of one optical fiber folded into two as U-shape, and of an optical passive circuit consisting of only photocouplers using a half mirror. CONSTITUTION:An optical fiber cable 5 is folded as almost U-shape to form a transmission line, and incoming/outgoing lines 6, 7 are respectively formed with the cable 5 and an optical relay device 8 is inserted to the lines. In transmitting data, e.g., from a terminal 14-1 to a terminal 14-3, a signal is converted into an optical signal at a node 11-1 and transmitted to a fiber cable 12-1, a photocoupler 9-1, the relay device 8, a folding section 5c, and a photocoupler 10-3. The signal is transmitted from the terminal 14-3 to the terminal 14-1 via a photocoupler 9-3, the relay device 8, a photocoupler 10-1, a fiber cable 13-1, and the node 11-1. In both the cases, the transmitted data includes an address and the data can be transmitted to the terminal of the desired node.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention provides high-speed and highly reliable communication between multiple terminals by sharing and using one optical fiber cable between each terminal. The present invention relates to an optical bus network system that can be used.

(2) Technical background Recently, communication systems such as data communication systems
Increasing number of terminals and amount of data transmitted: As the number of terminals increases, the demand for high speed and high reliability increases.
There is also a demand for something that can instantly communicate between arbitrary terminals.

(3) Prior Art and Problems For this reason, a bass network system as shown in FIG. 1, for example, has been put into practical use.

The system in the figure has multiple nodes 2-1 on a coaxial cable 1.
, 2-2, ..., 2-n to a plurality of terminals 3-1,
3-2, . . . , 3-n are electrically connected. In such a communication system, data can be sent and received between arbitrary terminals via a coaxial cable 1, etc., or data can be sent from an arbitrary terminal to multiple other terminals simultaneously. Is possible.
However, in the conventional type shown in FIG. 1, since the transmission band is limited by the coaxial cable, it is difficult to perform wideband and high-speed signal transmission. ..., there was an inconvenience that the transmission quality deteriorated due to noise due to impedance mismatching at the connection point between 2-n and the coaxial cable 1, etc.

It is also possible to replace the coaxial cable 1 in the system shown in Figure 1 with an optical fiber cable, but the structure of the coupling part 0 for coupling the optical fiber cable and each node to enable bidirectional transmission is possible. The disadvantages were that it became considerably more complicated, lowered its reliability, and increased its price.

(4) Purpose of the Invention In view of the problems with the conventional type described above, the purpose of the present invention is to configure upstream and downstream transmission lines in an optical bus network system using optical fibers bent into a substantially U-shape. Based on the concept,
High speed and high reliability due to simple configuration:.

−σ The objective is to enable signal transmission.

(5) Structure and object of the invention According to the present invention, in an optical bus network system in which a plurality of terminals share and use one optical fiber cable to communicate between each terminal, the optical The ends of the fiber cables are terminated without reflection, and the optical fiber cables are bent into a substantially U shape to form uplinks and downlinks, and terminals are connected to the uplinks and downlinks at each branching and insertion point via passive optical circuits. This is achieved by providing an optical bus network system that is characterized in that:

(6) Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an optical bus network according to an embodiment of the present invention.
Show the system. In the figure, 5 is an optical fiber cable that is bent into a substantially U-shape to form one optical transmission path, and 6 and 7 are uplink and downlink respectively constituted by the optical fiber cable 5. , 8 are optical repeaters inserted into these upstream and downstream lines. 9-1
, 9-2, 9-3, . . . , 9-m are optical couplers for optical signal insertion inserted into the uplink line 6 of each drop/add point,
10-1, 10-2, 10-3, ..., 10-m are optical couplers 9-1, 9-2, 9-3, ..., 9-, respectively.
This is an optical coupler for optical signal branching inserted into the downlink line 7 at the same branch/add point as m.

11-1, 11-2, 11-3, . . . , 11-m are each optical coupler at each branch/addition point and optical fiber cable 1 for transmission.
2-1, 12-2, 12-3, ..., 12-m and receiving optical fiber cables 13-1, 13-2, 13-
3, . . . , 13-m, and has photoelectric conversion and data transmission/reception control functions.

14-1, 14-2, 14-3, ..., 14-m are nodes 11-1, 112, 11-3, ..., 1, respectively.
It is a data terminal connected to 1-m, and in the figure, one data terminal is connected to one node, but 1
It is also possible to connect multiple terminals to one node.

In addition, both ends 5a and 5b of the above-mentioned optical fiber cable 5
are non-reflection terminated to prevent reflection of optical signals, for example by cutting diagonally and blocking external light. In addition, in the above, each optical coupler as an optical passive circuit inputs the optical signal from the transmission optical fiber cable to the uplink optical fiber cable by means of a half mirror inserted diagonally into the optical transmission line, or The optical signal from the downlink optical fiber cable is branched to the receiving optical fiber cable and output. In the configuration shown in FIG. 2, communication between each terminal is performed as follows.

For example, when transmitting data from terminal 14-1 to terminal 14-3, the data signal from terminal 14-1 is sent to node 1.
1-1, the transmission optical fiber cable 12-1, optical coupler 9-1, up line 6, optical repeater 8, up line 6, bending section 5C1 down line 7, optical coupler 10-3 , the receiving optical fiber cable 13-3, and the node 11-3 to the terminal 14-3. Conversely, when transmitting data from the terminal 14-3 to the terminal 14-1, the data signal from the terminal 14-3 is sent to the node 11-3, the transmission optical fiber cable 12-3, the optical coupler 9-3, Up line 6, bending section 5C1 down line 7
, the optical repeater 8, the downlink line 7, the optical coupler 10-1, the receiving optical fiber cable 13-1, and the node 11-1. In any of the above cases, the transmitted data includes the destination address of the transmitted data, that is, the destination address, and by taking in the transmitted data as information only in the node corresponding to this destination address, the desired node This makes it possible to send data to other terminals. FIG. 3 shows the configuration of nodes used in the system of FIG. 2.

The nodes in FIG. 3 include an electro-optical conversion circuit 17, an opto-electric conversion circuit 18, a packet transmitting circuit 19, and a packet receiving circuit 20.
, a collision detection circuit 21, a clock generation circuit 22, a transmission buffer memory 23, a transmission control circuit 24, a reception buffer memory 25, a reception control circuit 26, a data link controller 27 composed of a microprocessor, etc.;
Line interface 28-1, 28-2, 28-3, 2
8-4 etc. Note that the line interfaces 28-1, 28-2, 28-3, and 28-4 are connected to the terminals 29-1, 29-2, 29-3, and 29-4, respectively, and the electro-optical conversion circuit 17 and the photo-electric The conversion circuit 18 is coupled to the transmitting optical fiber cable 12 and the receiving optical fiber cable 13, respectively. In the node shown in FIG. 3, for example, when transmitting data from the terminal 29-1 to a terminal connected to another node (not shown), the terminal 29-1
The input data from 9-1 is sent to line interface 28-1.
The packet is inputted to the data link controller 27 via the data link controller 27, a destination address, a source address, various Fbl leg information, etc. are added to form a packet, and the packet is stored in the transmission buffer memory 23. Next, the transmission control circuit 24 determines the presence or absence of a received signal by monitoring the output of the opto-electrical conversion circuit 18. If there is no received signal, the transmission control circuit 24 determines that the optical transmission line is in an empty state and stores the signal in the transmission buffer memory 23. The stored packet is transferred to the packet transmitting circuit 19. A transmission electrical signal corresponding to the packet is created in the packet transmission circuit 19, converted into an optical signal in the electro-optical conversion circuit 17, and sent to the transmission fiber cable 12.
The optical signal sent to the transmission optical fiber cable 12 in this way passes through the uplink, the bending section, and the downlink as described above, and is received again by the reception optical fiber cable 13 of the same node, and is sent to the optoelectric conversion circuit. At step 18, the signal is converted into an electrical signal and input to the collision detection circuit 21.
The collision detection circuit 21 compares the input electrical signal with the previously transmitted electrical signal to determine whether the data was transmitted correctly and whether there was a collision with the transmitted signal from another node. and confirm that the transmission was successful. If it is detected through this determination that normal transmission is not being performed, data is retransmitted, for example. In the node of FIG. 3, when receiving data sent from a terminal connected to another node, an optical signal corresponding to the data is sent to the opto-electric conversion circuit 18 via the receiving optical fiber cable 13.
After being converted into an electrical signal, it is stored in the reception buffer memory 25 via the packet reception circuit 20.

At this time, the reception control circuit 26 determines whether the destination address in the received data, that is, the destination address, matches the address of its own node, and if they match, transfers the received data to the data link controller 27, If they do not match, the received data is deleted. The data link controller 27 transfers the input received data to the terminal corresponding to the terminal number information included in the destination address in the received data. FIG. 4 shows in detail an example of an actual communication procedure in the optical bus network system shown in FIGS. 2 and 3.

In the figure, from one terminal DTFA to another terminal DTE
It is assumed that data is transmitted to B, and MPUA and MPUB are connected to these data terminals DTEA and D.
Figure 2 shows a data link controller in a node connected to a TEB. First, basic processing is performed at the terminal DTEA to create a packet header including a destination address and a source address in response to a transmission start command. Next, message length, address data, packet type information indicating the type of data, message number, etc. are added to the given transmission data, and the data is transferred to the data link controller MPUA (hereinafter simply referred to as MPUA). When MPUA receives this information, it sends an acceptance signal AC.
1 is sent back to the terminal DTEA, and this information is edited (assembled) and error check bits are added to create a transmission packet, which is sent to the data link controller MPUB (hereinafter referred to as (simply referred to as MPUB). In MPUB,
When the transmitted packet is correctly received, an acceptance signal ACK2 is sent.
is transmitted to the MPUA, and the MPUA thereby deletes the transmitted packet, assuming that the transmitted packet has been correctly transmitted. In this case, if the MPUA cannot transmit the transmission packet correctly due to a collision of optical signals on the optical transmission path, etc., it will transmit the packet up to 16 times, and if it is still unable to transmit it correctly even after 16 transmission processes, it will send a message to the terminal DTEA. When the transmission packet is correctly transmitted to MPUB, the transmission packet is disassembled (disassembled) at MPUB, and only necessary data is transferred to the terminal DTEB. When terminal DTEB correctly receives the data, it sends an acceptance signal ACKV to MPUB, which causes MPUB to erase the received packet. Next, if terminal DTEB needs to send return data such as a confirmation message to terminal DTEA according to the content of the received data, it adds message length, address data, packet type data, etc. to the return data. and transfer it to MPUB. MPUB creates a transmission packet in the same manner as described above and transmits it to MPUA, and MPUA disassembles the transmission packet and transfers it to terminal DTEA.
In this way, data transmission for one cycle is completed,
Necessary data transmission is performed in a similar manner, and processing such as clearing of each buffer memory is performed by inputting a transmission end command, thereby completing all transmission procedures from the terminal DTEA. (7) Effects of the Invention As described above, according to the present invention, one optical fiber cable can be folded into two to form a U-shape configuration, and the optical passive circuit can also be configured only by an optical coupler using a half mirror. Therefore, an optical bus network system can be constructed with an extremely simple configuration, and the reliability of the system can be improved and high-speed signal transmission can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a conventional bus network system, FIG. 2 is a schematic block circuit diagram showing an optical bus network system according to an embodiment of the present invention, and FIG.
This figure is a block circuit diagram showing the configuration of nodes in the system of FIG. 2, and FIG. 4 is an explanatory diagram showing the transmission procedure in the system of FIG. 2.

Claims (1)

[Claims] 1. In an optical bus network system in which multiple terminals share and use one optical fiber cable to communicate between each terminal, the end of the optical fiber cable is terminated without reflection and the optical fiber cable is An optical bus network system characterized in that an uplink line and a downlink line are formed by bending the line into a substantially U-shape, and terminals are connected to the uplink line and downlink line at each branch/insertion point via an optical passive circuit.