SU1501076A1 - Device for interfacing user stations of local network - Google Patents

Abstract

The invention relates to data transmission and can be used in the construction of mono-channel local computer networks with multiple access, carrier monitoring and collision detection in control systems, data collection and processing based on them. The purpose of the invention is to increase the capacity and reliability of the network by implementing the functions of the priority of a packet coming from a common communication line, the time priority of transmissions of stations connected to the device, cut-off transmission of a "generator" station and compensation of phase distortions of signals received from a common line. connection. A device for interfacing subscriber stations with a local network communication line connected to a common communication line terminating at the ends with line equivalents and to subscriber stations comprises a transmitting unit, a receiving unit, an external priority node and a pulse generator. The transmitting unit contains interface receivers, transmission detectors, a switch, an internal priority node, a channel transmitter, transmission timers, and OR elements. The receiving unit contains a channel receiver, a collision detector, interface transmitters, a collision signal conditioner, a delay compensation circuit, a receive timer, an OR-NOT element, and an NOT element. 3 il.

Description

The invention relates to computer technology, in particular, to data transmission, and can be used in the construction of mono-channel local computer networks with multiple access, carrier control and collision detection in control systems, the collection and processing of information on their basis. ve

The purpose of the invention is to increase the capacity and reliability of the network by implementing the priority functions of a packet coming from a common communication line, the time priority of transmissions of stations connected to the device, cut-off transmission of a station generator and compensating for phase distortion of signals received from a common communication line. .

31501076

Ma FIG. 1 shows a block diagram of a device for interfacing subscriber stations with a communication link of a local network; in fig. 2 is a timing diagram illustrating the operation of a device when receiving from a common communication link; and FIG. 3 is a timing diagram illustrating the operation of the device during the transmission of a station connected to the device when receiving a packet from a common call from another device.

 A device 1 for interface of subscriber stations with a local network communication line connected to a common 15 communication line 2 terminating at the ends with equivalents of 3 lines and to subscriber stations A contains a transmitting unit 5, a receiving unit 6, an external priority node 7 and generator 8 pulses.

The transmitting unit 5 comprises interface receivers 9, transmission detectors 10, switch 11, internal priority node 12, channel transmitter 13, transmission timers 14 and OR elements 15.

Receiver unit 6 contains channel receiver 16, collision detector 17 interface transmitters 18, collision signal gels 19, delay compensation node 20, reception timer 21, OR NOT 22 elements and NOT 23. Connections between devices about-35 are labeled mi 24-45,

The operation of the device 1 for interface of subscriber stations with a communication line of a local network will be considered on the example of the following situations: 40

1, Transmitting one station connected to a device;

2, Transmitting multiple stations connected to a device;

3, Reception from a common link; 45

4, Transmitting a station connected to a device when receiving a packet from a common communication link from another device.

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In the initial state, i.e. in the absence of transmissions from stations 4; (, N) connected to the device 1, and transmissions in the common communication line 2 from other devices 1 at the outputs of the external priority node 7, the transmission detectors 10, the outputs of the first group of outputs of the internal priority node 12, the elements OR 15, the detector 17

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collisions, reception timer 21 and elements OR NOT 22, high logic levels are set. At the outputs of the second group of outputs of the node 12 internal priority, timers 14 of the transmission and inverter 23 are set low logic levels.

1, Transfer station 4,.

The packet transmitted to common line 2 enters device 1 via line 24, to the input of interface receiver 9, from the first output of which, via line 25I, the packet arrives at the input of transmission detector 10. From the second output of the interface receiver 9 via line 26, the packet arrives at the first information input of the switch 1 1. At the output of the detector 10, the transmission at this time sets a low logic level signal (envelope of the packet) 5 arriving via the -271 line to the first inputs of the timer 14, the transmission and the element OR 15. The second input of the element OR 15 (line 28) is set to low logical level, which leads to the installation of a low logic level signal at the output of the OR 15 element (coming through line 29 to the first input of the internal-priority node 12. Setting the low logic level to the first input of the internal-priority node 12 results in setting ohm and (N + OM outputs of the first group of outputs of node 12 of the internal priority of low-level signals, respectively, via lines 30j and 31 to the first enable input of switch 11 and the first input of node 7 of external priority. This causes the appearance of a packet at the switch output 11 (line 32) and the installation at the output of node 7 of the external priority of a low logic level signal coming through line 33 to the enabling input of the channel transmitter 13 HJ, therefore, the packet is transmitted to the common link 2. The end of the transmission of the packet from station 4 leads to the resetting of the device 1 in the described sequence.

If the packet duration exceeds the maximum allowed, a timer 14 is triggered, the output of which sets a high logic level signal (line 2B., /), Which causes blocking of the element OR 15 and;.

triggered element OR-IE 22. at the output of the element OR 15 and then on the lines 30, 31 and 33 a high logic level is established. c This leads to blocking of the transmission of station 4j .. Simultaneously with this,

element output OR NOT 22 (sets a low logic level signal, which on line 34f arrives at the input of shaper 19, a collision signal, which leads to sending station 4 through line 35, a Collision signal. Terminating the transmission of station 4 sets the device 1 to the initial state. Thus, blocking the transmission of the generating station 4 does not exclude the possibility of transmission — from other stations 4j (, N), which, compared to

The prototype improves the reliability and survivability of the network as a whole.

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2. Transmission of stations 4, and 42 to a common link 2.

The situation of simultaneous transmissions arises when stations using a local network use protocols of random access methods to a common communication link.

In this case, similarly to the previous one, at the outputs of the elements OR. 15 / and 15, low-level signals are set up, which are on lines 29, and 29 are fed to the first and second inputs of the internal priority node 12. Node 12 of internal priority analyzes the moments of installation of low logic level signals at its inputs, and if at the first input a low logic level signal was set earlier than at the second, t6 at the first and (N + 1) -M outputs of the first group of decodes of node 12 internal priority signals are set to a low logic level, which causes a packet from station 4 to be transmitted to the common link 2. At the same time, a high logic level is set at the second input of the second group of inputs of the internal priority node 12, which, via line 362, goes to the second input of the OR-NOT 22 element, which causes it to trigger. And, therefore, the start of the collider 19, t. e. Alert station 4 that its transmission is corrupted .. The station stops transmitting and device 1 starts to propagate

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As in the first situation, the high logic signal is removed from the line. With complete simultaneous installation of low logic level signals on the first and second inputs (lines 29f, 29) of the internal priority node 12 at the outputs of the first group of outputs of the internal priority node 12, the state of the high logic level does not change; at the first and second outputs of the second group of outputs of the node 12 internal priorities (lines 36, 36) are set to high logic level signals, i.e. in 1 cJiyMae, neither the transmission from station 4, nor the transmission from station 4 is released to the common link 2 and both

20 these stations receive an alert that their transmissions are corrupted. In this way, the number of collisions in the common link 2 of the local network is reduced, i.e. increases

25 network bandwidth in general. 3. Receive a packet from a common link 2.

The packet is received by the channel receiver 16, which is output from the line

30 37 enters the inputs of the 17 collision detector and the delay compensation circuit 20. At the first output of the collision detector 17, a low logic level signal is set (envelope of the packet), coming through line 38 to the second input of the receive timer 21 and the first inputs of the interface transmitters 18; (, N). Pulses from the generator 40 of pulses (line 39) are fed to the first input of the receive timer 21. At the exit of the timer. 21 receptions (line 40) establishes a low logic level signal which is analyzed by the external priority node 7 and

In case of the absence of a low logic level at this moment in time, line 31 is blocked (prohibiting installation on line 33 of a low logic level and setting to

50 lines 41 of a low logic level) channel transmitter 13 and node 12 of internal priority. This is necessary to eliminate collision situations in shared link 2 due to

55 the possibility of the beginning of the transmission stations 4j. (, N) connected to the device 1. The response time of reception timer 21 (blocking time of the channel transmitter 13 and internal priority node 12) is selected from the following conditions: first, it must exceed the maximum time to resolve a conflict situation (meaning fixing conflict, extension of transmission, removal of transmission, etc. for a transmitting station that has entered into conflict; secondly, it must be shorter than the minimum message duration (taking into account the extension time of the conflict transmission) in order for station 4 to receive ayuscha packet, if busy its receive buffer could arrange oncoming intersection provoke ctolknovenie cottage and consequently receive the receiving delay, as the proportion of damaged package

wives be retransmitted to her after some time. From the output of compensation circuit 20 (line 42), the received packet arrives at the second inputs of the interface Hbix transmitters 18, -18 (4 and, since the first inputs of the interface transmitters 18 | -18 are set to low logic level, the packet from the outputs of the interface 8c transmitters (transmitted by lines to the information inputs of the respective stations.

In the event of a collision in the common link 2, a low logic level is set at the second output of the collision detector 17, which through line 44 enters the input of the HE element 23, which causes the output of the HE element 23 (line 45) of a high logic level and, therefore, the triggering of the elements lOTi-HE 22, -22 | d, -start of collision signal formers 19, i.e. signal transmission Collision with all stations connected to device 1.

4. Transfer station-4. at the moment when the device 1 receives a packet from the common link 2.

This situation is a combination of the first and third situations and reduces to the fact that the first and second inputs of the internal priority node 7 are set to low logical levels corresponding to the transmission of station k (line 31) and receiving a packet from the common link 2 (line 40 ). If the low-level signal on line 40 was lower, or at the same time

With a low logic level signal 31 on the first output of the external priority node 7, a low logic level signal is set, which via line 41 goes to the (K + 1) -th input of the internal priority node 12. Line state 33 (high level) i.e.

the state of the second output of the external priority node 7 does not change (the channel transmitter 3 is blocked). The internal priority node 2 analyzes the state of the input lines 29J-29u and 41 and so. as on lines 29 (and 41 are set low logic levels, the first output (transmits station 4) of the second group of outputs (line 36) is set to 1 high logic level signal, which will lead to the transmission of station 4

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forcing her to stop transmitting. If the low logic level signal on line 31 is set before the low logic level signal on line 40, then a high logic level is maintained at the first output of the external priority node 7 (line 41), a low logic level signal is set at the second output of the external priority node 7 arriving via line 33 to the enable input of the channel transmitter 13, i.e. the release packet transmitted by station 4 to a common link 2. Otherwise, the installation of low logic level signal on line 40 later than the installation of low logic level signal on line 31 is ignored by external priority node 7. Introduction to the device 1 node 7 external priority allows -. Do not block incorrectly started transmission stations 4, -4ts5 transmissions started at the moment when the packet is already being received by device 1, but has not yet reached station 4; (, N) connected to device 1, and thus reduce the number of collisions in a common link 2 and therefore increase the capacity of the network as a whole.

Claims (1)

Invention Formula Device for interface of subscriber stations of a local network, containing-20 9150 transmitting and receiving units, the transmitting unit contains N interface receivers, N transmission detectors, a switch, an internal priority node and a channel transmitter, the i-ro input (, N) of the interface receiver is the device input for connecting to the i-th output ( , N) subscriber station, the first output of the i-ro (i, N) interface receiver is connected to the input of the i-ro (, N) transmission detector, the second output of the i-ro (, N) interface receiver is connected to the i-m (, N) the informational input of the switch, the i-th {i --- l, N) control input of which is connected to the ith (, N) output of the first group of outputs internal priority, the switch output is connected to the information input of the channel transmitter, the receiver block contains a channel receiver, a collision detector, N interface transmitters and N drivers of the collision signal, the channel receiver input connected to the output of the channel transmitter is input the output of the device for connecting to a local network communication line, the output of the channel receiver is connected to the input of the collision detector, the first inputs of the N interface transmitters are combined and connected to the first collision detector home, exit. 35 i-ro (, N) of the interface transmitter is the output of the device for connecting the 1st (, N) subscriber station to the input signal, characterized in that, in order to increase the capacity and reliability of the local network by implementing the functions the priority of the packet incoming from the common communication line, the time priority of the transmissions of the subscriber stations connected to the device, the cut-offs transmitting the generating station and the compensation of the nitrogen distortion of the signals received 25 thirty ABOUT 20 - g 10 15 -,. 35 40 45 25 thirty from the common communication line, it is equipped with an external priority node, a pulse generator, the transmitting unit is equipped with N timers and N OR elements, and the receiving unit is equipped with a receive timer, a delay compensation unit, an NOT element and an N-OR element, and the first inputs of the i-ro (, N) transmission timer and i-ro (, N) of the OR element are combined and connected to the i-ro (; N) output of the transmission detector, the second inputs N of the transmission timers are combined and connected to the output of the pulse generator and the first input of the reception timer of the reception unit, the output of the i-ro (, N) timer before and connected to the first input (, N) of the element OR NOT and to the second input of the i-ro (, N) of the element OR, the output of which is connected to the i-th (, N) input of the internal priority node, (NY + 1) -th whose input is connected to the first output of the external priority node, the second output of the external priority node is connected to the enable input of the channel transmitter, the i-th (, N-) output of the second group of outputs of the internal priority node is connected to the second input of the i-ro (, N) element. OR-NOT., (N + l) th output of the first group of outputs of the internal priority node. Connected to the first input of the external priority node, the second input of which is connected to the output of the receive timer, the second input of the receive timer is connected to the first output of the collision detector, and the input of the delay compensation unit is connected to the output of the channel receiver, the second inputs of the N interface transmitters are combined and connected to the output of the delay compensation node, the second output of the collision detector is connected to the input of the HE element, the output of which is connected to the third the inputs of N elements are OR NOT, and the output of the i-ro () of the element OR is NOT connected to the input of the i-ro (, N) of the collider signal generator. EH g. y "ai" howl gav wm gvzh. №bZi & sis.,. ,,  1 Г ±: ГЛ.