JPH0269041A - Time division multiplex communication system with one slot - Google Patents

Abstract

PURPOSE:To realize N:N communication by a simple method by using only one slot as a common slot and successively giving transmitting rights to each node, with nodes having no transmitting data being excluded from getting the rights. CONSTITUTION:At each node, whether or not its own node has transmitting data is checked and, when a slot is 'empty', whether or not the node of its own station has transmitting data is checked. When the transmitting data exist, the data are transmitted by setting the slot to a use state. At the same time, each node adds '1' to a 'specified number of times counter' set in the node of its own station and successively transmits the data to the overhead section and data section of the slot. When an arrived slot is not 'empty', whether or not the data in the slot are the answer to the data sent last time by the node of its own station is checked and, at the same time, presence of the data transmitted to the node of its own station is checked. When the arrived slot is not 'empty' and the data in the slot are not the answer to the data sent last time from the node of its own station, the slot arrived at the next node is sent as it is.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a time division multiplex communication system, and is a communication system that is most suitable for a local area network (LAN) used as a Ta-based or horizontal information communication network. be.

[Conventional technology]

A time division multiplex communication method (TDMA method) has been known as a system used in LAN.

In the TDMA system, a main station and each node station are connected in series using a transmission medium such as a bus cable, and each frame (large frame on the time axis) is divided into subdivided time slots in order to receive a transmission request. By assigning it to a station, it is possible to transmit continuous digital signals without interruption.

By the way, when a network is configured with one master station and multiple node stations, the master station manages the entire network and has the function of generating the overall reference clock, and the node stations Works synchronously.

A clock is used to ensure that the time information on the sending and receiving sides completely matches, ensuring accurate transmission of information.
Thereby, the phase information is extracted from the received signal, and the built-in oscillator is synchronized with it and reproduced.

In addition, when connecting each station in a ring shape,
The master station is equipped with a delay circuit for holding the bit allocation of one frame on the ring.

Frame synchronization is used as a means of digitization
A certain synchronization pattern, such as that used in CM (pulse sign ratio change 1ll), is often used.

On the other hand, there is a token passing method as another communication method.

The token ring method, which is common among token passing methods, connects a plurality of node stations in series on one closed ring.

This method belongs to the packet switching type, in which a special frame called a free token, which is a transmission permit, is sequentially routed between connected stations in a pre-ordered order, and the order of transmission is assigned.

Then, the node station you want to transmit is a fleet
When the receiver accepts the call, it converts it into a busy token, adds the destination address, own station's address, and own station information, converts it into a token addressed to the next station, and sends it to lEH&.

Furthermore, a station that does not need to transmit converts a token addressed to itself into a token addressed to the next station and sends it. All node stations constantly monitor the destination address in received packets, and if the frame is addressed to their own station, they take it into their own buffer and allow the received frame to pass through as is.

Furthermore, when the transmitted packet goes around and returns to the transmitting node, the transmitting node newly transmits a fleet token and grants transmission rights to other nodes.

[Problem to be solved by the invention]

Conventional time division multiplex communication systems increase the degree of freedom in communication between nodes connected to the network by using multiple channels in the number of slots.

However, for that purpose, N(N-1
) slots, complete NUN compensation is not possible.

That is, in the conventional example, since multiple slots are fixed, even if a certain node has no data to transmit, the corresponding slot is transmitted on the transmission path, resulting in a problem in that the transmission efficiency decreases.

On the other hand, in the token ring system, the node that holds the transmission data sequentially captures the tokens to
Although the drawbacks of the DMA system have been solved, token frames can sometimes be lost, which not only requires management, but also requires a backup system such as a token regeneration sequence in the event of loss.

Furthermore, it was not possible to avoid transmission delays due to waiting in line and an increase in variations thereof.

In addition, when adding new nodes or removing previously operating nodes, consideration must be given to maintaining normal token transfer procedures.

Therefore, the present invention adopts the TDMA method, which can be controlled relatively easily, as a control method, and uses one slot.
To provide a time division multiplex communication system that enables N:N transmission in a simple manner by using it as a common slot, giving transmission rights to sequential party nodes, and avoiding nodes with no data to transmit. It is.

[Means to solve the problem]

The present invention eliminates multiple slots, allocates one slot as a common slot for transmission, and shares it among all stations, thereby realizing a circuit switching function on a time slot and making time sharing possible for NUN communication. It is a multiplex communication method.

The present invention consists of a master station and a node station connected in series by a transmission medium (coaxial cable), and the master station generates a time-division reference clock and has a frame control function.

Then, the information is sequentially transferred from one station to the next station, each station plays and repeats each pit of the transmission frame, and the master station has a FIFO (first in first out) function. A delay is applied to maintain the frame period.

〔Example〕

The present invention will be explained based on the drawings.

FIG. 1 is a flowchart showing the transmission procedure at each node.

■Each node checks whether there is data to be sent to its own node, and if the slot is "empty", it determines whether there is data to be sent to its own node, and if there is data, it determines that the slot is in use. The data is transmitted, and at the same time, 1 is added to the "regular number counter" set in the own node, and the data is transmitted sequentially to the slot, overhead part, and data part.

In addition, when there is long data, the regulation number counter is
Since there is a possibility that a slot may be occupied for a long time and interfere with the communication of other nodes, the number of times that the same node can use the slot continuously is defined, and the counter is incremented by 1 each time a transmission is performed.

(2) If the arrived slot is not "empty", it is checked to see if it is a reply to the previous data sent by the own node, and further it is confirmed whether there is any data to be sent to the own node.

If there is data to be sent, check that the number of continuous transmissions is within the specified number of times based on the contents of the specified number of times counter, and if it is within the specified number of times, the data is transmitted with that slot in use, 1 is added to the counter, and the slot is sent to the next node.

■If the slot that arrived is not "empty" and is not a reply to the data sent out by the previous node, the slot that arrived at the neighboring node is sent out as is.

(2) If the continuous transmission exceeds the specified number of times, no data is sent, the slot is returned to empty, the contents of the ``regular number of times counter'' are initialized, and the slot is sent to the next node.

■If the arrived slot is not "empty", check whether it is a reply to the data sent from the local node last time,
This is a reply to the data sent last time by the local node, and if the local node has no data to send, return the slot to empty,
Initialize the contents of the "regular number counter" and send the slot to the next node.

Next, the transmission data format is shown.

A special splitter or non-data symbol or the like is used to indicate the start of a slot. It consists of 1 byte, and this start bit contains details of the AC part, which also serves as frame synchronization.
78 Bit number r B/E J is ON when the slot is in use (busy), and ON when it is empty.When a node with transmission information recognizes that B/E is "0", it /E=1
When the transmission is finished, the B/E starts again.
=O.

When dividing and transmitting information, r ES is set to 1" if the information is the widest, and is set to 0 if it is the first or intermediate information.

"Number" is used when dividing and transmitting information, starting with number 1 and assigning numbers in order.

"Data length" is the length of data to be loaded on r DATA J, and indicates "90" at maximum.

r PPPrMRRRJ is priority
Used as an information area to indicate.

1 15 bit number An absolute address that corresponds one-to-one to each node, and every node has its own unique address. l10=O
When , it indicates an individual address (specific node), and when I/G=1, it indicates a group address.

When all the 16-bit addresses are 1'', it is a broadcast address, and when all the pits are 0', it is an invalid address.

Each consists of 2 bytes.

DATA: Place the transmission data in this part.

If the amount of data to be sent is larger than the rDATAJ area length, it will be divided and sent; conversely, rDATAJ
If it is less than the area, add dummy information and rDA
Satisfies the "TeA" area.

Note that although the D^TAJ area length is set to 90 bytes in this embodiment, the optimum value shall be selected depending on the data transmission speed, transmission path length, average length of transmission data, etc.

Fe2: Adopts a cyclic redundancy check (CRC) method to detect frame-by-frame transmission errors, and consists of 2 bytes (16 bits). Received frame (excluding frame check sequence field)
If the CRC value of the frame check sequence field is not the same as the CRC value of the frame check sequence field, it is detected as a frame check error.

ED: −+≧, 1 It means the end of the slot, and in this embodiment, it is composed of 1 byte and is set as HACrrrrrr.

〔Effect of the invention〕

The present invention adopts a time division multiplex communication method with a relatively simple control method, uses one slot as a common slot, sequentially grants transmission rights to the pot nodes, and bypasses nodes with no data to transmit. NU in a relatively easy way
N communication was realized and the transmission speed was significantly improved.

That is, when comparing the delay time characteristics with the token ring method as shown in FIG. 2, the delay is only about 20%.

In addition, in comparison with conventional time division multiplex communication systems,
By using one slot, the average occurrence interval is 10
''''The transmission speed has been improved several times compared to the one with 20 channels in SEC.Furthermore, the present invention is extremely useful for industrial use, achieving elimination of transmission errors while improving transmission efficiency. It is a useful invention.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the transmission procedure of the present invention;
The figure is a graph showing comparison data of the transmission speed with the token ring method, and FIG. 3 is the comparison data of the transmission speed between the present invention and the multi-channel slot method. fi delay time (see) delay time (see) procedural amendment October 6, 1986

Claims (1)

[Claims] 1. In a time division multiplex communication system that is composed of a master station and a plurality of node stations connected in series and that enables N:N communication, one slot on a frame is a common slot for transmission. A time division multiplex communication system that uses a single slot, and is characterized by the fact that it is allocated as a single slot and used by all stations. 2 The above time division multiplex communication system consists of a master station that has the function of generating a time division reference clock and controlling frames, a regulation counter for controlling the long-term use of slots, and a check for the presence or absence of transmission data at its own node. According to the result, the data is transmitted and a slot in which 1 is added to the above specified number of times counter is sent to the next station node, and if there is data to be sent, the next station node determines the received slot and the contents of the specified number of times counter. When data is transmitted while the slot is in use, and the number of consecutive transmissions exceeds the specified number of times, the slot is initialized without transmitting data, and the content of the slot is the reply sent from the previous node. And if the local node has no data to send, the slot is returned to empty, the specified number of times counter is initialized, and the slot is sent to the next node, and if the slot is not a reply to the local node, the slot is sent directly to the next node. The N
2. The time division multiplex communication system using one slot according to claim 1, wherein: N communication is performed. 3 The above slot has an access control part next to the start delimiter that also serves as frame synchronization, and the access control part includes a flag part indicating whether the slot is in use, and a flag indicating whether the information is the last information or intermediate information. 2. The time division multiplexing unit according to claim 1, wherein the time division multiplexing unit comprises a part, a part numbered sequentially from 1 when dividing and transmitting information, a part indicating data length, and an information area indicating priority. Communication method.