JPS5951794B2 - Control method of distributed electronic exchange - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the control method of a distributed electronic switching system in which switching functions are distributed to each terminal.

In particular, the present invention relates to a switching control system suitable for a private packet switching system with a function of reserving information transmission timing in a linear switching network. In a data communication network or a communication network in which data signals and voice and other signals coexist, a switching system is being considered in which each terminal is connected to a single line and switching functions are distributed to each terminal. FIG. 1 is a block diagram of a conventional linear switching network.

1 is a transmission line, and coaxial or twisted pair wires are used.

Reference numeral 2 denotes a terminal portion for absorbing transmitted waves and eliminating reflections.

3a to 3e are interfaces between various terminals and lines, and are used to send information received from the terminal to the transmission path, receive information on the transmission path, and pass this information to the terminal if it is addressed to the own terminal. be.

4a to 4e are terminals that use this switching network.

These are connected via interfaces 3a to 3e, respectively, to a transmission line via short lines. FIG. 2 is a flowchart of information transmission using a conventional control system. A indicates that it is determined that there is no information being transmitted on the transmission path. B indicates that information is sent to the transmission path.
C indicates that it is determined that the transmitted information did not collide on the transmission path. D indicates waiting for the retry interval when a collision occurs. In such a conventional system, if two or more terminals try to start transmitting information at almost the same time, an incorrect determination may be made in FIG. 2A due to propagation delays in the transmission path.

That is, each terminal determines that there is no information being transmitted on the transmission path, two or more terminals use the transmission path at the same time, and the information transmission must be retried based on the determination of C. When there are few requests for transmission, the frequency of collisions is low, but when the number of requests increases, the frequency of collisions increases, making it impossible to use the transmission path to its maximum potential. As a result, the time from the generation of a transmission request to the completion of transmission becomes long, and in some cases this time diverges.
The reason why such a method has been used in the past is that the distances between terminals make it difficult to synchronize all terminals at a common timing.

In general, in parallel control devices such as multiprocessor devices that can be installed in the same room or rack, multiple independent control devices share the same bus bar to control information transmission. There are already various inventions, but they usually involve synchronizing signals between devices by some means, and the rise or fall times of pulses as signals to be passed are synchronized in a predetermined time relationship. ing. However, for a system in which signals are generated between devices at completely independent timings as in the present invention, there has been no known method for avoiding information collisions on a transmission path. In addition, in the case of an information processing system that accommodates a relatively small number of terminals, the number of requests to transmit information packets is small, the distance between devices is short, and the number of devices is limited, In the event of conflicting information transmission requests from
A method has been proposed in which one terminal among them is determined to have the highest priority and is permitted to use the transmission path (Japanese Patent Laid-Open No. 48-6
(No. 2311) In a system with a large number of competitors, this requires priority setting control according to the waiting time, which is disadvantageous to utilizing the maximum transmission efficiency.

The present invention aims to improve this and provides a control method that prevents information collisions from occurring on the transmission path. The present invention provides a mode switch at one end of the transmission line,
The present invention is characterized in that each terminal is provided with a function of reserving the timing at which a terminal having information to be transmitted will transmit the information according to the pulses output by the terminal.

That is, the present invention provides a mode switch that is connected to a transmission line and switches the mode of the transmission line between a reservation mode and an execution mode, and when there is information to be sent, the timing of information transmission is reserved in the reservation mode. (in order of proximity to the switch) and circuit means disposed in each terminal to transmit information at that timing when in execution mode.

Furthermore, this means that the bit-by-bit synchronization of information transmission by each terminal can be unique for each terminal, and the timing of information delivery can be guaranteed for each transmitting/receiving pair.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a block diagram of a linear switching network according to an embodiment of the present invention.

1 is a transmission path, 2 is a terminator, 3a to 3e are interfaces, and 4a to 4e are terminals.

Reference numeral 5 denotes a mode switch, which determines a reservation mode and an execution mode and notifies all terminals thereof.

The interfaces 3a to 3e have a reservation function added to the functions of the interfaces 3a to 3e explained in FIG. Each of the terminals 4a to 4e is connected to the transmission line 1 by a short line via these interfaces 3a to 3e.
branch is connected to. l FIG. 4 is a flowchart illustrating the operation of the mode switch 5.

F indicates sending of a reservation instruction pulse indicating the start of reservation mode. G indicates that it is determined whether all terminals have completed their reservations. H indicates that it is determined whether a terminal that has made a reservation exists. I indicates the sending of a pulse indicating the execution mode. J indicates that it is determined whether all information corresponding to the reservation has been sent. F to J under normal operating conditions
is repeatedly circulated, and the reservation mode and execution mode are alternately switched. However, when there is no sending request, F to H are short-circuited and the reservation mode continues. FIG. 5 shows a flowchart of information transmission control according to an embodiment of the present invention.

K indicates that it is determined whether or not the mode is a reservation mode. L
indicates that a reserved pulse is inserted into the transmission path. M indicates that the execution mode is fixed. N indicates that the information is sent out on the transmission path in accordance with the reserved order. Each terminal that has a transmission request inserts a reservation pulse when it enters reservation mode, but before that, it counts the reservation pulses inserted by other terminals, and this value determines the order in which information is sent when it enters execution mode. becomes. The methods by which each terminal inserts a reservation pulse into the transmission path are (a) seat designation pulse insertion method...method in which a reservation pulse is inserted at the bit position assigned to each terminal, and (1) first-come, first-served queue designation pulse insertion method.・・・
・Method of inserting reservation pulses from each terminal on a first-come, first-served basis, Part 2
There are seeds.

Figure 6 shows the above (a) seat designation pulse insertion method.
2 is a pulse time waveform diagram of a waveform on a transmission path viewed from a position of a terminal end 2 on the opposite side from a mode switch 5. FIG.

Further, FIG. 7 similarly shows a pulse time waveform diagram for the above-mentioned matrix first-come-first-served designated pulse insertion method. In FIGS. 6 and 7, reference numeral 11 indicates a reservation instruction pulse sent from the mode switch 5. In FIG. a', b', and d' are single pulses from each terminal that has made a reservation; for example, a' indicates a reserved pulse from the terminal 4a. 12 is an execution instruction pulse sent out from the mode switch 5.

a" and b" are information sent from each terminal, for example, a" indicates information from terminal 4a. Above (a) and (
Considering the advantages and disadvantages of method (a), in method (b), each terminal is given a separate reservation pulse insertion timing in reservation mode according to its position on the transmission path, and the time in reservation mode is is fixed at a time that is long enough for all terminals to make reservations.

The first method is a method in which the terminals that wish to make a reservation send reservation pulses to the transmission line 1 in the order of their proximity to the mode switch 5.
The reservation mode time changes according to the number of reservations. When the number of terminals connected to transmission line 1 is small, there is no difference between these two methods, but when the number of terminals increases, in method (a), it is necessary to devote enough time to reservation mode for all terminals to reserve. Therefore, the (guchi) method is more efficient in using the lines. FIG. 8 is a diagram showing an example of the configuration of the mode switch 5. As shown in FIG.

21 is a driver, 22 is a receiver, 23 is an execution instruction pulse generator, and the execution instruction pulse may have the same code as the information end flag, and 24 is a reservation instruction pulse generator.

25 is an identification unit that identifies information received from the receiver,
When it is a reservation instruction pulse, 01 is "l", when it is a reservation pulse, 02 is "l", and when the information end flag is detected, 03
Outputs “1” to .

26 is RS flip-flop, 27 is OR gate, 28
is an and gate.

29 is a counter, which sets 1 when there is an input to S, counts up when there is an input to U, counts down when there is an input to D, and sets ``1'' when the count value is ``O''. is configured to output.

30 is a down counter which sets a value when there is an input to S, counts down to the input to C, and outputs ``1'' when it reaches 0.

To explain the operation of this circuit, when a reservation instruction pulse is output, the counter 29 is reset, and the counter 30 is set with a clock having a time twice the delay time of the transmission line.

If there is a reservation here, the power counter 29 will be counted up,
Execution instruction generation unit 23 due to timeout of counter 30
Start. As a result, when the execution instruction pulse is output, the flip-flop 26 is reset and the clock is stopped through the AND gate 28. When the identification section 25 receives the information break, it counts down the counter 29, and when this value reaches "O", the reservation pulse generation section 24 is activated to output a reservation instruction pulse. 9th
The figure is a diagram showing an example of the main part configuration of each terminal interface when implementing the seat designation pulse insertion method.

32 is a reservation pulse generation block; 33 is an information input terminal; 34 is an input terminal indicating that there is information to be sent; 35
3 is an output terminal indicating the timing of information transmission, and 36 is an information output terminal.

When you want to send out information, the output Q of flip-flop 26
is "1", so when the identification circuit 25 receives the reservation instruction pulse via the receiver 22, it sets the counter 29 and sets the reservation pulse insertion timing unique to each terminal in the counter 30. Counter 29 counts the number of reservation pulses until counter 30 times out. When the counter 30 times out, the counter 29 stops counting and the reserved pulse generation block 32 sends out a reserved pulse. Next, the identification circuit 25
When the information is received through 2 and the end flag is detected, the counter 29 is counted down, and when the current value reaches ``O'', it outputs ``1'' to the output terminal 35 to notify the lower-level device of the timing of information transmission. .

FIG. 10 is a diagram showing the main part of each terminal interface when implementing the matrix first-come, first-served designated pulse insertion method.

37 is a receiver to which differential inputs between the transmission line 1 and the driver 21'' are applied.

38 is an identification circuit, regarding the input from the receiver 37,
If it is a reservation instruction pulse, "1" is output to 01, "1" is output to 02 when a reservation pulse collides, and "1" is output to 03 when an information end flag is detected.

39 is a dummy load for making the impedance equivalent to that of the coaxial cable.

When you want to send out information, the output Q of flip-flop 26
is "1", so when the identification circuit 38 detects the reservation instruction pulse via the receiver 37, the reservation pulse generator 32 sends out the reservation pulse.

At this time, if there is a reservation pulse on transmission line 1, the receiver 37
detects a collision of reservation pulses, and this is transmitted to the AND gate 28, which prohibits the transmission of reservation pulses. That is, the reservation pulse from the preceding terminal has priority, and the sending of the reservation pulse is retried after detecting the end of the reservation pulse from the preceding terminal and waiting for a predetermined timing. At this time, the counter 29 is incremented each time a collision is detected. This method foresees the existence of reservation pulses from the preceding terminal. Therefore, when there is a reservation pulse from the preceding terminal, a collision always occurs. In other words, the number of detected collisions matches the number of reservations from terminals that are located earlier. As a result, when the reservation pulse ends, the counter 29 registers the reservation. The number of attempts to insert a pulse will be indicated. Next, when the identification circuit 38 detects the information end flag, the flip-flop 26 is reset and the counter 29 is counted down. This directness is “0”
'', it outputs 1 to the output terminal 35 to notify the lower-level device of the timing of information transmission. As described above, when transmitting information in the switch control system of the present invention, the transmission timing is reserved in reservation mode, so that no information collision occurs on the transmission path. Therefore, the usage efficiency of the transmission path can be maximized. Furthermore, the time from when a transmission request is generated until the transmission is completed is shortened. The present invention can be applied not only to general data terminals but also to instantaneous terminals such as telephones, fax machines, etc. that require periodic transmission and reception of information, and has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional linear switching network. Figure 2 is a flowchart of information transmission using the conventional method. FIG. 3 is a configuration diagram of a linear switching network according to an embodiment of the present invention. Figure 4 is an operation flowchart of the mode switch section. FIG. 5 is a flowchart of information transmission in an embodiment of the present invention. FIG. 6 is a waveform diagram on the transmission path in the seat designation pulse insertion method. FIG. 7 is a waveform diagram on a transmission path in the matrix first-come, first-served designated pulse insertion method. FIG. 8 is a diagram illustrating a configuration example of a mode switch circuit. FIG. 9 is a diagram illustrating a main part configuration of a terminal interface circuit when implementing the seat designation pulse insertion method. FIG. 10 is a diagram illustrating a main part configuration of a terminal interface circuit when implementing a matrix first-come, first-served designated pulse insertion method. 1... Transmission line, 2... Terminator, 3a
~3e...Interface, 4a~4e...Terminal, 5...Mode switch, 11...Reservation instruction pulse,
12... Execution instruction pulse, 21.2'... Line driver, 22... Line receiver, 23... Execution instruction pulse generation unit, 24... Reservation instruction pulse generation unit,
25...Identification circuit, 26...Flip-flop, 2
7...or gate, 28...and gate, 29.
...Up-down counter, 30...Down counter, 32...Reservation pulse generation section, 33...Information input terminal, 34...Transmission request input terminal, 35...Information sending timing output terminal, 36・・・Information output terminal, 38・
...Identification circuit, 39...Dummy load.

Claims (1)

[Claims] 1.Equipped with one transmission line in which reflections at both ends are suppressed, and a plurality of terminals including a pair of transmitters/receivers that are branch-connected to this transmission line, and use the above transmission line in a time-sharing manner to transmit each of the above In a control system for a switching network that transmits and receives information between terminals, a mode switch connected to one end of the transmission line and switching the mode of the transmission line between reservation mode and execution mode sends a reservation instruction pulse onto the transmission line, and then The terminal detects the reservation instruction pulse, the terminal that has the sending information detects the reservation pulse from the previous terminal, counts the number of reservation pulses received after the reservation instruction pulse, records it as the reservation order, The reservation pulse is sent out in order from the first terminal to the second terminal.
After the mode switching device counts and stores the number of reservation pulses transmitted from each terminal and sends an execution instruction pulse to the transmission path, each terminal detects the execution instruction pulse and presets the reservation pulse in the reservation mode. The distributed electronic switching system is characterized in that the sending terminal sends the information in accordance with the reservation order, and the mode switching device confirms the information for the total number of reservations and transfers control to the sending of the reservation instruction pulse. control method.