JPS63237635A - Data transmission system - Google Patents

Abstract

PURPOSE:To improve the efficiency of data transmission by constituting the titled system so that a station whose station number coincides with a vaounting obtains a transmission right to transmit a data. CONSTITUTION:In the network connected to a transmission line 100, a station whose power source is turned on first comes to be managing station, and a frame header is transmitted from this managing station to the transmission line 100. Due to the transmission of this frame header, a carrier flows through the line 100 and its is detected by respective equipments 200, and a slot counter 73 is initialized, then, the managing station transmits a proxy packet to make the counters of respective stations increment. When the counter 73 is incremented and its counting value comes to one, a first station 1 obtains the transmission right and transmits a data packet to the transmission line 100. In this transmission, carriers which flow through the line 100 are detected similary by respective equipments to increment their counters and the counting value come up to two, thus the following station 2 obtains the transmission right. In such a way, the data transmission through the network can be effectively executed.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a data transmission method suitable for local area networks, and in particular to a data transmission method with improved data transmission efficiency. be.

(Prior Art) FIG. 9 shows a bus type network configuration.

To explain the conventional data transmission method based on the same figure, the transmission line (pass line > ioo has N devices (stations) 20
0 is connected. Each device has a unique number 1, 2.3
・・・・・・・・・N is attached, of which @1
The devices from 4 to 4 are in the active state (hereinafter referred to as mounted stations), and the remaining devices are considered to be non-mounted stations. In the figure, non-mounted layers are surrounded by broken lines. Among the installed stations, the device that is powered on first functions as a management station for the entire network. In addition, this network management station allows all mounting stations to be equal, and even if the current network management station goes down, another mounting station can immediately start up. Therefore, the entire system will not go down.

゛Once the network management station is determined by inputting the source,
Transmission line 1 transmits the network transmission start signal as a packet
Send to 00. At this time, a carrier flows through the transmission 1100. This carrier is detected in each mounting layer, and an internal counter is initialized in accordance with this detection.

Assuming that device 2 is now a network management station, no station can have transmission rights in the initialized state. Therefore, the network management station 2 sends out a packet called a proxy packet to flow the carrier onto the transmission line 100. Each station detects this, increments each internal counter, and sets the count value to 1. At this point, since the count value is 1, device 1 has the transmission right. Then, the device 1 sends a data packet to the transmission fa100 if there is data, or a dummy packet if there is no data.

A carrier flows through the transmission line 100 again by sending out a data packet or a dummy packet, and each station detects this carrier and further increments its internal counter. In this way, the transmission right is sequentially transferred each time the count-up occurs.If the implementation layer that was given the transmission right as described above breaks down for some reason, or if the transmission right is given to a non-implementation layer. , no packets are sent from those stations. Therefore, each station cannot detect the carrier and the counter is not incremented, so the transmission right is not transferred to another station.

In this state, the network management station sends out a proxy packet to increment an internal counter.

When all the stations have finished their transmission operations, the network management station sends out a transmission start signal again, and the same operation as above is repeated.

However, in the conventional data transmission method described above,
There were the following problems.

First, when the transmission right is transferred to a non-implemented layer, no packets are sent from this non-implemented layer, so the network management station sends out a proxy packet as described above. Therefore, when there are few implemented layers and many non-implemented layers, the network management station must send a proxy packet each time, which takes time and reduces data transmission efficiency.

Second, since the transmission right can be equal for all stations and there is no priority, the transmission request of a station that has a lot of data to transmit and requires more transmission rights than other stations cannot be satisfied.

(Problems to be solved by the invention) As mentioned above, in the above conventional data transmission method,
When the number of implemented layers is small and the number of non-implemented layers is large, transmission efficiency is poor, and since there is no priority for transmission rights, there is a problem that the requests of stations that require many transmission rights cannot be satisfied.

The present invention has been made based on the above-mentioned conventional problems, and
The purpose is to provide a data transmission method that can improve transmission efficiency and take into account the priority order of transmission rights.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a data transmission system in which a plurality of stations are connected via transmission lines and data is sent and received between each station. , a detection means for detecting a carrier flowing in a transmission line, a counting means for counting up each time a carrier is detected, a variable means for varying the count-up value of the counting means at regular intervals, and a count-up value determined for each station in advance. The present invention is characterized in that it includes a determining means for determining whether a station number and a count value match, and a station whose station number and count value match obtains a transmission right and transmits data.

(Operation) In the present invention, carriers flowing through the transmission line are detected by a plurality of stations connected via the transmission line.

The count value of the counter is incremented every time a carrier is detected. Further, a station number is set in advance for each station, and when this station number and the count value match, that station obtains the transmission right.

Particularly, in the present invention, the count-up value can be varied so that the transmission right can be set to be transferred to a desired station.

(Embodiment) FIG. 2 is a block diagram showing the configuration of each station to which the present invention is applied, and N stations 200 are connected to the transmission line 100 as shown in FIG. 9 above. .

As shown in the figure, this station 200 is the center of the @ location.
A PU 10, a ROM 20 that is connected to the CPU 10 and stores &lJ control programs, a RAM 30 that stores various transmission data, and a transmission buffer 40 and a reception buffer 50 that temporarily store packets when transmitting and receiving packets. , a bus interface 60.

FIG. 1 shows the functions of the CPU 10 of this embodiment in blocks, and this CPU 10 includes a packet detection section 71 that detects a received packet, and a packet analysis section 72 that analyzes the data content of the detected packet. and a slot counter (internal counter) 73 which is incremented by a signal from the packet analysis unit 72 as described later.
A self-transmittable determination unit 74 determines whether the count value of the slot counter 73 matches a preset own station number, and a packet that reads data from the RAM 30 and sends it as a packet if transmission is possible. The generator includes a generator 75.

FIG. 3 shows the structure of one frame of data sent to the transmission line 100. One frame consists of packets sent out from each station numbered from 1 to N, starting with a frame header 80 which is a transmission start signal from the management station.

The packet format of the above frame header 80 is set to 4.
Shown in Figure (A). This frame header 80 is composed of 7 words, each word of which is 16 bits from 0 to 15. The first four words are preamble or general purpose area 80a.
Various data required for transmission control can be stored in this preamble 80a. The upper 8 bits of the next word are an area 80b representing the type of packet, and a number assigned to the frame header is set in this area 80b. Lower 8 bit area 80c
contains the address of the receiving station. The transmitting station address is stored in the upper 8 bit area 80d of the next word.

In this embodiment, the 8 bits in area 80e are configured as shown in FIG. 4(B). That is, the first O bit stores information as to whether the frame header is an odd number or an even number (this is called the number of frame headers), and if the frame header is an odd number, " 1 n, and "0" is stored for even numbers.

Further, the count-up number of the slot counter 73 is stored in advance in the upper four bits from the 4th bit to the 7th bit. In this embodiment, when the number of frame headers is odd (bit 0 is "1"), the count up number is fixed to 1, and when the number of frame headers is even (bit O is "O"), the count up number is fixed to 1. This is the count up number set by the upper 4 bits.

Furthermore, an error code CRC is stored in the final area 80f, forming the frame header 80 of this embodiment.

Next, the operation of this embodiment will be explained with reference to the drawings from FIG. 5 onwards.

In the network connected to the transmission line 100 as shown in FIG. 9, the station that is powered on first becomes the management station,
A frame header is transmitted from this management station to the transmission line 100. By transmitting this frame header, the carrier flowing through the transmission line 100 is detected by each device 200, and the slot counter 73 is initialized. Next, the management station sends out a proxy packet to increment the counter of each station.

The counter 73 is incremented and the count value becomes 1.
Then, the first station 1 obtains the transmission right and sends the data packet to the transmission line 100. By sending out this transmission packet, the carrier flowing to transmission a100 is detected in each device in the same manner as described above, and its counter is incremented. Then, the count value becomes 2 and the next station 2 obtains the transmission right. In this way, data is sequentially transmitted in a frame configuration as shown in FIG. 7(A).

When the data transmission of one frame is completed, the management station transmits the second (even numbered) frame header 11110.
Send to 0. Since this frame header is an even-numbered frame header, "0" is stored in the O-th bit of the area 80e.

Also, if 2 is set as the counter up number stored in the upper 4 bits at this time, the slot counter 73 of each station that received this frame header will be 2.
It is incremented and the count value becomes 2. Therefore, the first transmission right is given to station 2 rather than station 1. Thereafter, each time a carrier is detected, the count-up value becomes 2, so only stations assigned even numbers will obtain the transmission right (see FIG. 7(B)).

Furthermore, in the next frame, the frame header is an odd-numbered frame header, so the count-up value is 1. Therefore, the transmission right is given in order from station 1 to station N, as shown in FIG. 7(A). (Figure 7 (C))
. Then, in the fourth frame, as shown in FIG. 7(D), transmission rights are given to every other even-numbered station.

The processing procedures of these management stations and each station have been organized and
This is shown in the flowcharts in FIGS.

In this way, according to the present embodiment, the count-up value of the slot counter 73 of each station is set to 1 when an odd-numbered frame header is sent out, and the count-up value of the slot counter 73 of each station is set to 1 in advance for the frame header sent out from the management station, and the count-up value of the slot counter 73 of each station is set to 1 when an odd-numbered frame header is sent out. Since it is set to 2 at the time of transmission, even-numbered stations are given the transmission right for each frame, but in odd-numbered months, control can be made so that the transmission right is given every other frame. Therefore, it is possible to determine the priority order of transmission rights, and if only odd-numbered months are used as actual devices, control can be performed without giving transmission rights to non-implemented stations, so the time required to transmit one frame of data is reduced. Network data transmission can be performed efficiently.

FIG. 8 shows a frame structure of another embodiment of the present invention. In this embodiment, the frame header number of bit O stored in the area 80e of the frame header 80 is eliminated, and only the counter up number stored in the upper 4 bits is used.

In this example, the count up number is set to 5,
Therefore, only stations that are a multiple of 5 can obtain transmission rights in each frame. In this case, by dividing the maximum number of stations that can be connected to the network by the number of installed stations as the count-up number, and assigning the individual number of the actual device to the multiple, the transmission right will always be given to the actual device. become. Therefore, the time required for sending a proxy packet from the network management station to the non-implemented station can be omitted, and data transmission efficiency is improved.

[Effects of the Invention] As described above, according to the present invention, even when the number of actual devices is small, the number of times proxy packets are sent to non-implemented stations can be reduced, and data transmission efficiency is improved.

Furthermore, since the priority order of transmission rights can be determined for each station, the request of a station that requires more transmission rights than other stations can be fully satisfied.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a block diagram showing the configuration of an embodiment of a device to which the present invention is applied, and FIG.
The figure shows the structure of one frame, Figure 4 shows the packet format of the frame head, Figures 5 to 6 are flowcharts showing the processing procedure of the management station and each station, and Figure 7
The figure shows the frame structure of the first embodiment, and FIG. 8 shows the frame structure of the second embodiment.
FIG. 9 is a diagram showing the frame structure of the embodiment, and FIG. 9 is a diagram showing an example of a network. 10... CPU 20... ROM 30... RAM 40... Transmission buffer 50... Reception buffer 60... Bus interface 71... Packet detection section 72... Packet analysis section 73...・Slot counter (internal counter) 74...
- Local station transmission determination unit 75...Packet generation unit 8o...Frame header 100...Transmission line 2Q○...Station (device)

Claims (1)

[Claims] (1) In a data transmission system in which multiple stations are connected via a transmission line and data is sent and received between each station, there is a detection means that detects carriers flowing through the transmission line, and a counter that is counted up each time a carrier is detected. means, variable means for varying the count-up value of the counting means at regular intervals, and determining means for determining whether a station number predetermined for each station and the count value match, A data transmission method in which the station that matches the agreement obtains the transmission right and sends out data.