JPS61224748A - Loop transmission system - Google Patents

Abstract

PURPOSE:To prevent a terminal device from not being restored due to return of transmission information of the own station by detecting a flag representing communication direction when it is received, not receiving the transmission information from the own channel and receiving only the information from a specific opposite party. CONSTITUTION:A switch SW1 acts like an input device to an AND gate G1, and it is changed over to the Q position or Q' position of a register R2. The AND gate G1 passes through the transmission line information from a register R1 only when the input from the switch SW1 is logical 1. For example, when it is selected that a flag 1 is set in the communication from a master station to a slave station, the switch SW1 in the master side channel is changed over to the lower position, an output of the Q' of the register R2 opens a gate to the information sent from the slave channel while setting the flag is 0. The switch SW1 in the slave side channel is changed over uppwer position to open the gate thereby fetching the information of the flag 1 by using the output of the Q of the register R2.

Description

[Detailed Description of the Invention] [Summary] In a loop network consisting of node devices that connect terminals to the network and transmission paths that connect each node device on a loop, the communication direction is specified to each node device. A function that sends information added to the information from the terminal as a flag, and a configuration that detects the flag during reception and does not receive information sent from the own channel, but only receives information from a specific party. This prevents the terminal from being unable to recover due to its own transmitted information being returned as is.

[Industrial Field of Application] The present invention relates to a transmission method in a loop network consisting of a node device that connects a terminal device to the network and a transmission path that connects each node device in a loop. This invention relates to a transmission system that prevents information transmitted by a local station from returning to the local station even in the event of a failure.

[Prior Art] In the loop type transmission line system, one time slot is normally allocated to communication per channel.

For example, as shown in FIG. 4(a), when terminal A and terminal B communicate, one time slot (for example, n
When terminal A transmits information to the time slot n, terminal B extracts the information from time slot n, and after extracting the information, transmits the information again to the same time slot n. This enabled two-way communication.

In this method, when the node device 3 becomes defective and enters a bypass state due to a network failure, as shown in FIG. After that, it is received again by terminal A. At this time, the information will be received incorrectly as the information transmitted by terminal B.

In such a state, the terminal usually does not have a recovery method against the return of its own transmitted information as it is, so it is often impossible for the terminal to recover again. .

Therefore, in conventional wave technology, in order to avoid the occurrence of such a phenomenon, a method has been proposed in which two time slots are allocated to communication on the (1) channel.

In this method, communication from terminal A to terminal B uses time slot n', and communication from terminal B to terminal A uses a different time slot n'.

In this case, terminal A has time slot n, and terminal B
Since it does not receive time slot n', it does not receive its own transmission information.

[Problems to be Solved by the Invention] In the conventional method described above for avoiding reception of information transmitted by the own station, two time slots are used for one communication channel, so a communication channel with a certain transmission capacity is used. There is a problem that the number of communicable channels on the transmission path is reduced to 1/2.

The present invention aims to provide a new loop transmission method that solves this problem.

[Means for Solving the Problems] FIG. 1(a) shows a block diagram of the principle of the loop transmission system of the present invention.

In FIG. 1(a), only node device 1 and node device 2 are shown as typical node devices in the loop transmission path, and terminal A3 is shown as a terminal device connected to node device Wtl.
, only the terminal B4 is representatively shown as a terminal device connected to the node device 2.

Each node device 1.2 includes a channel section 11.12, which is an interface circuit section corresponding to each terminal, and a multiplexing section 12.22, which multiplexes information on each channel and interfaces with a transmission path.

Terminal A3 connects to channel a of node device 1, and terminal B
4 is connected to the opposite channel b of the node device 2, and performs two-way communication between the terminal A3 and the terminal B4.

Each channel unit 11.21 of each node device 1.2 is set with information indicating one direction of communication (for example, terminal A→
Terminal B1 or Terminal B → Terminal A) is provided, and this information is added to the information from the terminal as a flag and sent out.

In addition, each channel unit 11.21 detects the flag when receiving information from a transmission path, and does not receive information transmitted from its own channel, but only information received from a specified communication partner. Provide a function to receive and send to the terminal.

[Operation] FIG. 1(b) shows the configuration of a time slot in the present invention. As shown in the figure, each time slot n,
, n + l, n + 2. In addition to the information bits, a flag (P) F is provided for - and -, and this is set depending on the communication direction.

When terminal A and terminal B shown in FIG. 1(a) communicate,
In channel a of node device 1 to which terminal A connects and channel b of node device 2 to which terminal A connects, for convenience, a is assumed to be "parent Jsb is r child."

For example, the flag that distinguishes which direction of bidirectional communication is most simply set to 1 bit, and "Parent j's transmission information is "1"".
The flag indicating the transmission information of "r child" can be set as "0".

For example, if channel (a) is configured with this, channel a will set flag 1'' on information from terminal A,
Insert into time slot n and send out.

Furthermore, when channel a receives transmission path information, it checks the information flag of channel n, and if it is "l", it does not take it in; if it is "0", it takes it and sends it to terminal A.

Since the channel b side of the node device 2 is the r child j, the setting is completely opposite to that of the channel a. That is, the information sent from terminal B is sent with a flag O'' added to it, and upon reception, the information with flag 1'' is set to be taken in, but the information with flag 0'' is set not to be taken in.

In this way, it is possible to prevent information sent from the own channel from being received, and even in the event of a network failure,
This will prevent it from becoming impossible to recover.

The structure of frame information in the above explanation is an example,
This also includes cases where there are differences in the number of bits, the order of flags and information, etc. Further, the format of a flag that distinguishes which direction of bidirectional communication is used also includes a case where the flag is composed of a plurality of bits.

[Example] The present invention will be described in more detail below with reference to Examples shown in FIGS. 2 and 3.

FIG. 2 is a block diagram of a main part of a receiving circuit of a channel section of a node device to which the present invention is applied. FIG. 3 is a time chart of this embodiment.

In FIG. 2, syc is a synchronization detection circuit, which detects a time slot synchronization signal from multiplexed information on a transmission path.

TG is a timing generator, which outputs the timing TI% of each data bit and the timing T2 of the n-th slot flag, as shown in FIG.

R, is a register that stores transmission path information at timing TI.
The output is latched by the AND gate G1.

R2 is also a register, which is a circuit that latches transmission path information at timing T2 and resets it at the end of that time slot, and outputs its ζ side output or side output to AN.
Input to D gate G1.

SW is a switch which, as an input to the AND gate GI, switches between the Q side and the ζ side of the register R2.

AND gate GI has an input from switch SwI of 1"
Only when , transmission path information from register R is passed.

For example, if it is determined that the flag "1" is set for communication from the "parent" to the "r child", "In channel a on the parent side, SW1 is set to the lower side, and the r The gate is opened for information sent from channel b on child j side with flag "0".

In the channel b on the r-child j side, swl is set upward, and the ζ-side output of the register R2 opens the gate for the information of the flag 1'' to take it in.

[Effects of the Invention] As explained above, according to the present invention, the number of transmission channels is not reduced by half (and even in the event of a network failure, the transmitted information of the own station is returned to the own station, making it impossible to recover again). It can be prevented, and its practical effects are extremely large.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram and time slot configuration diagram of the present invention, Fig. 2 is a main block diagram of an embodiment of the present invention, Fig. 3 is a time chart of the embodiment of the present invention, and Fig. 4 is a conventional example. FIG. In the drawing, 1.2 is a node device, 3.4 is a terminal device, 11 and 21 are node devices/channel sections, 12.22 is a node device/multiplexing section, syc is a synchronization detection circuit, TG is a timing generator, R1 and R2 are registers, SWI is a switch, and Gl is an AND gate. Half 1 Silk (α9 Sano θ・Iεhand q1! All 5 machines 4th

Claims (1)

[Claims] In a loop network consisting of a node device that connects a terminal to the network and a transmission line that connects each node device in a loop, a pair of nodes that perform bidirectional communication via the network. each channel unit (11) of the node device (1), (2) to which the terminal (3), (4) is connected;
(21) means for adding information indicating one direction of communication as a flag to the information from the terminals (3) and (4) and transmitting the flag to the transmission path; and for receiving information from the transmission path. In this case, the terminal (3) detects the flag and does not receive the information sent from its own channel, but only receives the information sent by the specific party.
(4) A loop transmission system characterized in that it is configured to include means for sending data to.