SU1290569A1 - Access driver for common communication channel - Google Patents

Abstract

This invention relates to a related technique. The purpose of the invention is to increase the speed by reducing the time to resolve conflicts. The device contains, interface unit 1, transmitting buffer unit 2, shift register 3 transmissions, encoder 4, transmitter 5, receiver 6, decoder 7, shift receiving register 8, receiving buffer unit 9, collision detector 10, control unit 11, clock r p 12, four counters 13, 17, 20, 33, address decoder 14, address register 15, grs pulses 16, register 18, switch 19, four single-oscillators 21, 23, 24, 34, three trigger 22, 27, 35 , three el-And 25, 26, 29, inverter 28, three el-and OR 30-32 ,. the short pulse shaper 36 and the communication line 37. If the sign of successful transmission from the flip-flop 35 does not arrive, then this means that there is a draw on line 37. - The device does not receive the right to transfer until the only device that has been granted the right to transfer has been identified. Thus, the number of participants in the drawing is limited, which leads to a decrease in the time to resolve the conflict. 2 Il. (L 37 to with O ate

Description

The invention relates to communication technology and can be used in the organization of communication systems and computing systems with a common communication channel, telemetry and telecontrol systems.

The purpose of the invention is to increase speed by reducing the time to resolve conflicts.

FIG. 1 shows a block diagram of a device for controlling access to a common communication channel; in fig. 2 - the algorithm of the device.

The common access channel access control device (FIG. 1) comprises an interface unit 1, transmitting buffer unit 2, shift register 3 of transmission, encoder 4, transmitter 5, receiver 6, decoder 7, reception shift register 8, receiving buffer unit 9, collision detector 10;; control unit 11, clock generator 12, first counter 13, address decoder 14, address register 15, pulse generator 16, second counter 17, register 18, switch 19, third counter 20, first one-oscillator 21, first trigger 22, the second one-shot 23, the third one-shot 24, the first element And 25, the second element And 26, the second trigger 27, the inverter 28, the third element And 29, the first element OR 30, the second element OR 31, the third element OR 32, the fourth counter 33, the fourth one-shot 34, the third trigger 35, the driver 36 short pulses and communication line 37.

The device works as follows.

The interface unit 1 generates the data that must be transmitted to the communication line, and in parallel transmits it to the transmitting buffer unit 2. The data from the transmitting buffer unit 2 are written in parallel form into the shift register 3 of the transmission. The pulses of the clock generator 12 are fed to the shift input the register 3 and at its output the data in a serial code are formed, arriving at the first input of the encoder 4, the third input of which receives the pulses of the clock generator 12.

From the output of encoder 4, the data in the Manchester code is transmitted to

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five

0

five

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five

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sensor 5 and transmitted to communication line 37.

The input of the control unit 11, which coordinates the operation of the device blocks from the output of the 10 collision detector, receives a collision signal if the transmitted to the communication line 37 and the received data do not match.

When the power is turned on, the first one-shot 21 starts up. If by the moment the time interval specified by this pulse the link busy signal 37 does not appear, the first trigger 22 will be set to the falling edge of the pulse. The output of the first trigger 22 sets it to its initial state the third and fourth counters 20 and 33, and through the first element OR 30 generates a signal allowing data transmission. With the presence of this signal, as well as the requirements of the data transmission interface unit 1, the availability of data in the transmitting buffer unit 2 and the absence of communication line 37, the control unit 11 enables operation of the encoder 4 and the shift register 3. The resolution signal is removed when a collision signal arrives from the detector for 10 collisions on line 37, the first single vibrator 21 is cleared and there is no signal from the first trigger 22.

Restart of the first one-shot 21 occurs when the channel occupation signal is removed. Thus, the first one-shot 21 and the first trigger 22 form a timer, which allows the channel silence intervals to be fixed if they exceed a predetermined value. With simultaneous receipt of channel channel signals from several devices connected to the communication line 37, a conflict situation arises. In this case, when transmitting information to the communication line 37 through the second element I 26, a second trigger 27 is set, the signal of which indicates that the device has come into conflict and it should take part in the draw of the right to occupy the communication line 37.

A drawing is a decentralized procedure for randomly selecting a device that receives the right to transfer information. Signal

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from the output of the first element OR 30, enters the control unit 11, allowing the transfer of information. This signal is established as a result of the raffle, as well as when the first trigger 22 is set, or when a successful transmission signal is present. Signal about the presence of a successful frame transfer in-. the formations are formed using the fourth one-shot 34, the third trigger 35 and the driver 36. In order to distinguish a successfully transmitted frame of information from frames distorted during collisions, the minimum

over The numbers are compared by trial and error, independently by each device connected to the communication line 37.

The random binary number is generated by the pulse generator 16 and the second counter 17 and is recorded in register 18 according to the signal of the transmission request coming from the transmitting buffer unit 2. The random number is analyzed one bit per step. A step is a period of time during which a device can reliably determine

the frame length is chosen so that the situation on the communication line 37. The duration of the transmission of the frame of information was longer than the duration of the collision situation.

The fourth one-shot 34 is triggered when a channel occupancy signal appears from the output of the decoder 7, while the driver 36 generates a short pulse on the leading edge of the signal, setting

The quality of the comparison step depends on whether a conflict has arisen or a silence interval has been fixed when analyzing the next bit of a random 20 number. The bitwise analysis corresponds to the choice of one number from the group of numbers on a given segment by dividing the segment into halves. In this case, the unit in the checked discharge is the initial state of the third trigger 35. leads to the generation of a resolution signal

The pulse duration of the fourth one-shot 34 is longer than the duration of the collision situation in the channel, but less than the transmission duration of the smallest possible frame, so if at the time of the end of the pulse of the fourth single-vibrator, the output signal from the decoder .7 is present, then the third one. trigger 35 will be set to one, i.e. on witts signal of the presence of a successful transfer. If the sign of successful transmission from the output of the third trigger 35 does not arrive, then this will mean that there is a draw on communication line 37 and the device does not receive the right to transmit until the draw is completed until you play

the transmission from the output of the first element OR 30. The number of the checked bit is determined by the number recorded in the third counter 20 and received at the control inputs of the switch 19, while the selected register register 18 arrives at its output. If, at a given transmission enable signal, the device without conflict 35 transmits information to the communication line, a third trigger 35 will be installed, forming a sign of successful transmission, the rally will be completed, the third and fourth counters 20 and 33 will be reset.

If, during the transmission of information, a collision is detected, then through the second element I 26 a second trigger 27 will be set, and 40

The only device (from the third element OR 32 per unit to the communication line 37) that obtains the right to transmit information. Thus, the number of participants in the game is limited and does not increase at the expense of devices that are not 50 participating in the initial collision, which reduces the time to resolve the conflict.

If this device has become a participant in the conflict and takes part in the drawing, then the procedure for comparing random numbers of devices participating in the drawing will be increased, the contents of the third counter 20 will increase, which will allow an analysis of the next bit of the random number.

If, when analyzing the next bit, the transmission resolution signal is not generated, and on the communication line 37, the transmission of another device is detected, the device drops out of the raffle and goes into standby mode from the third flip-flop 35. zi 37

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over The numbers are compared by trial and error, independently by each device connected to the communication line 37.

The random binary number is generated by the pulse generator 16 and the second counter 17 and is recorded in the register 18 according to the signal of the transmission request coming from the transmitting buffer unit 2. The random number is analyzed one bit per step. A step is a period of time during which a device can reliably determine

 situation in the communication line 37. The duration of the comparison step depends on whether a conflict has arisen or a silence interval has been fixed when analyzing the next digit of a random number. The bitwise analysis corresponds to the choice of one number from the group of numbers on a given segment by dividing the segment into halves. In this case, the unit in the checked bit leads to the generation of a resolution signal

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the transmission from the output of the first element OR 30. The number of the checked bit is determined by the number recorded in the third counter 20 and received at the control inputs of the switch 19, while the selected register register 18 arrives at its output. If, at a given transmission enable signal, the device without conflict 5 transmits information to the communication line, a third trigger 35 will be installed, forming the sign of successful transmission, the rally will be completed, the third and fourth counters 20 and 33 will be cleared.

If, during the transmission of information, a collision is detected, then through the second element I 26 a second trigger 27 will be set, and che0

This will increase the content of the third counter 20, which will allow analysis of the next bit of the random number.

If, when analyzing the next bit, the transmission resolution signal is not generated, and on the communication line 37, the transmission of another device is detected, the device drops out of the raffle and goes into standby mode from the third flip-flop 35. zi 37

is determined by the absence of a signal about its own transmission at the input of the inverter 28 and the presence of a busy signal at the input of the third element AND 29, as a result of which the second trigger 27 is set to the zero state, and the third and fourth are set to the zero state through the second OR 31 element counters 20 and 33.

It is possible that during the next analysis of the discharge, none of the devices connected to the communication line 37 and participating in the drawing will receive the right to transmit a message. In this case, a silence interval occurs. This interval is recorded by the third one-shot 24. The duration of the silence interval is determined by the second one-shot 23, which is triggered by a signal to drop the line 37 and the presence of a signal to request a transmission. The duration of the elementary silence interval is chosen such as to guarantee reliable determinations of the situation — when no device received the right to transmit (i.e., not less than the dual signal propagation time between the two most remote devices). The third one-shot 24 starts at the end of the pulse from the second one-shot 23. The output signal of the third one-shot 24 through the first element I 25 causes the unit to be added to the third counter 20 and thus provides an analysis of the next bit of the random number.

It is possible that the random numbers selected by the devices participating in the raffle will be the same. In this case, in a number of steps equal to the binary random number size: a, the rally will not be completed with successful transmission and a single signal at the output of the higher bit of the third counter 20 will go to the fourth counter 33, fixing the number of attempts to take the communication line 37, t . number of draws.

in which this device took part. In addition, this signal records the new random number to register 18 and the procedure of the raffle is repeated. When several raffles do not lead to conflict resolution, a signal is generated at the output of the high bit of the fourth counter 33, to the evidence

that either the hardware is out of order, or the load on the system is extremely high. The first one-shot 21 and the first trigger 22 provide the possibility of transmitting information in the case when the device that received the right to transfer information, during the rally, was out of order. The rest of the devices connected to the communication line 37 and not participating in or leaving the rally are in standby mode for a successful transmission signal. In this case, this signal is generated by the first trigger 22.

Claims (1)

Invention Formula Access control device 0 to a common communication channel containing serially connected interface unit, transmitting buffer block, transfer shift register, encoder and transmitter, the output of which is connected 5 with the communication line and the input of the receiver, the output of which is connected to the serially connected decoder, the receive shift register and the receiving buffer unit, the output of which is connected to the first input of the interface, the second output of which is connected to the first input of the control unit, the second input of which is connected to the second output of the transmit buffer from the unit whose second input is connected to the first output of the control unit, the second output of which is connected to the second inputs of the encoder and the shift shift register, the third input of which is connected to the third input of the encoder and the clock generator output, with the outputs of the shift receive register connected to the corresponding inputs of the address decoder whose output is connected to the second input of the receiving buffer unit and the first input of the address register, the output of which is connected to the third input of the receiving buffer unit, the fourth input of which connected to the output of the receive shift register and the input of the first counter, the output of which is connected to the second input of the address register, and the second output of the decoder is connected to the third input of the control unit, the fourth input of which is connected to the output of the collision detector, the first and second inputs of which are connected respectively to the output at 0 five 0 five the transmitter and the transmitter input, which is so that, in order to improve speed by reducing the time of conflict resolution, sequentially connected pulse generator, the second counter, the register, the switch and the first OR element, whose output is connected to the fifth input, are entered control unit, the third input of which is connected to the inputs of the first and fourth single-vibrators, a short pulse shaper, the first inputs of the second one-oscillator, the first trigger, the third one-oscillator, the third And element, and the third The second and third inputs of which are connected respectively to the outputs of the fourth one-shot and short pulse shaper, and the output of the third trigger is connected to the first input of the second OR element and the second control input, the second input of which is connected to the second input of the second one-shot and the first control input of the register, The second control input of which is connected to the first output of the third counter and the first input of the fourth counter, the second input of which is connected to the output of the second OR element and the first input The second counter, the second input of which is connected to the output of the third element OR, the first input of which is connected to the output of the second element AND and the second input of the second trigger, the output of which is connected to the first input of the first element And, the second input of which is connected to the output of the third single-oscillator and the third input the second one-shot, the output of which is connected to the second input of the third one-shot, and the output of the first one-shot is connected to the second input of the first trigger, and OR, the third input of which is connected to the output of the first trigger, the output of the first element, AND is connected to the second and second inputs of the second element by the second input of the third element OR, OR, the third input of which is connected to the second outputs of the third account, to the first input of the second trigger and the output of the third element And, the second input of which is connected to the output of the inverter, the input of which is combined with the first input of the second element And and connected to the second output of the unit thirty The sensor is connected to the control inputs of the switch, and the output of the fourth counter is connected to the second input of the interface unit, with the second input of the second And element connected to the output of the collision detector. five 0 control, the second input of which is connected to the second input of the second single vibrator and the first control input of the register, the second control i input of which is connected to the first output of the third counter and the first input of the fourth counter, the second input of which is connected to the output of the second OR element and the first input of the third counter whose second input is connected to the output of the third OR element, the first input of which is connected to the output of the second element AND and the second input of the second trigger, the output of which is connected to the first input of the first ele cient And, a second input coupled to an output of the third monostable multivibrator and a third input of the second monostable multivibrator, whose output is connected to a second input of the third monostable multivibrator, the output of the first monostable multivibrator is connected to a second input of the first flip-flop, and 5, the output of the first element I is connected to the second input of the third element OR, and the second outputs of the third count are the output of the first element And is connected to the second input of the third element OR, and the second outputs of the third count are The sensor is connected to the control inputs of the switch, and the output of the fourth counter is connected to the second input of the interface unit, with the second input of the second And element connected to the output of the collision detector. VNIIPI Order 7918/59: Circulation 660 Random polygons pr-tie, Uzhgorod, st. Project, 4 Subscription