SU1437872A1 - Device for interfacing subscriber stations with communication line of local network - Google Patents

Abstract

The invention relates to computing and can be used in the construction of mono-channel local number networks with multiple access, carrier control and collision detection. The aim of the invention is the extension of the class of tasks by enabling the connection of a group of subscriber stations. The goal is achieved in that the device containing the channel transmitter, the first interferer receiver and the transmission detector and the timer in the transmitter unit, and the channel receiver, the collision detector and the first interface transmitter and the collider signal transmitter are entered into the receiver unit N -1 interferer transmitters and N-1 collision shapers, and in the transmitting unit a switch, a priority node and N-1 transmit detectors and N-1 interface receivers. 9 il. sh (l

Description

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The invention relates to computing technology, in particular, to data transmission, and can be used in the construction of single-channel local computer networks with multiple access, carrier control and collision detection in control systems, the collection and processing of information based on them,

The aim of the invention is to expand the class of tasks of the device by enabling the connection of a group of stations.

Fig. 1 shows a block diagram of the device proposed; Fig. 2-4 shows a functional diagram of a channel transmitter, a switch and a priority node, respectively; in fig. 5-9 is a functional diagram of an interface receiver, a transmission detector, a collision detector, an interface transmitter, a collider signal generator

respectively.

The device is a multiplexer 1 - (FIG. 1) connected to a common link 2, terminating at the ends with impedances of $ 3 and; to subscriber stations 4, contains a front-end unit 5 and a receiving unit b, Transmitting unit 5 consists of a group of interface receivers 7, transmission detectors 8, switch 9, priority node 10, channel transmitter P and timer 12. Receiving unit 6 consists of a channel receiver 13 ,, the collision detector 14, the interface transmitters 15 and the formers (generators) 16 of the collision signal.

Fig. 1 also shows lines 17-30 of the connections of the elements of the device.

The channel transmitter 11 (FIG. 2) is designed as a series-connected current-limiting resistor 31, a key 32 and a diode 33, 34 and 35 isolators, connected in series by a current-limiting resistor 36 and key 37, the element OR 38, the element 39 and the key 40,

The switch 9 (fig.Z) contains the elements OR 41 and the element And 42,

Priority node 10 (FIG. 4) contains elements OR 43, elements OR NOT 44, 45 and 46.

The interface receiver 7, shown in FIG. 3, performs the function of receiving the information sequence

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through the device interface and consists of a comparator 47, a transformer 48 and current limiting resistors 49 - 52.

In the absence of an information sequence on the primary winding of the transformer 48 (line 17), the inputs of the comparator 47 are shorted and a voltage is set at its outputs, which from the direct output (line 18) goes to the input of the switch 9.

Dp matching the impedance of the interface cable parallel to the secondary winding of the transformer 48 are connected resistors 49 and 50, the common point of which is connected to the reference voltage output of the comparator 47s

The information sequence supplied to the primary winding of the transformer 48 comes from the secondary winding to the inputs of the comparator 47, from the direct output of which is fed to the input of the switch 9,

Transmitting detectors 8 contain (Fig.6) comparators 53 and 54, current limiting resistors 55-64, storage capacitors 65 and 66, and diodes 67 and 68.

The collision detector 14 is provided with components (FIG. 7), comparators 69 and 70, buffer amplifiers 71 and 72, HE element 73, transistors 74–81, current-limiting resistors 82-104, and storage capacitors 105-109.

Interface transmitters 15 contain (FIG. 8) buffer amplifiers 110-112, an element OR 113, a transistor 114, current-limiting resistors 115-124, storage capacitors 125-127, and a transformer 128.

The drivers (generators) 16 of the collision signal contain (FIG. 9) with an OR element 129, a transformer 130, current limiting resistors 131-133, storage capacitors 134-136, and a delay element (inductance) 137.

The device 1 for coupling the subscriber stations operates as follows

In the Transmission mode, information from the station 4, where i 1, N, on line 17 is fed to the input of the interface receiver 7, from the outputs of which on line 18 is fed to the corresponding input of the switch 9, and via line 19 - to the input of the detector 8. De0

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tector 8 generates a signal at its output. A transmission transmitted by a low level on line 20 to the corresponding input of node 10, which causes a low level node 10 to be transmitted on line 1 to the 1st control input of switch 9, and Signal Allowing Transmission Allowed by Low Level on Line 22; Setting a low level on the control input of switch 9 causes information to appear on line 23. Setting the Signal Allowing Transmission to Low Level on Line 22 causes the channel to be connected. 1 1 to the common link 2 and transfer to it information from the output of switch 9 and start timer 12. In case the duration of the transmission on line 2 exceeds the maximum packet transfer duration defined by the exchange protocol, the output of timer 12 is set to low Long packet signal, which via line 2A goes to the second input of the channel transmitter 11, which will lead to the disconnection of the channel transmitter 11 from the general communication line 2 and to the termination of transmission. Signal Dismiss Transmission resolution, i.e. setting a high level on line 22, sets timer 12 to its initial state. If an attempt is made to simultaneously transmit from several stations 4, line 25 will set a low signal. The conflict in the block, which via line 25 will go to the fourth input of the channel transmitter 11, which will result in the installation of a DC level perceived by all connected to the common link 2. lines 2 communication devices 1 as Stolenie.

In the Receive mode, information from the common link 2 is fed to the input of the channel receiver 13, from the output of which via line 26 is fed to the inputs of the detector 14 and interface transmitters 5, the Detector 14 determines the availability of information on line 2 and generates an output signal received at the output low level on line 27 to the inputs of interface transmitters 15, which causes the appearance at the outputs of interface transmitters 15 of information received from line 2 and its transmission through lines 28 to stations 4,

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in addition to the situation in line 2 of the collision, i, e. simultaneous transmission of two or more stations 4, the output of the detector 14 generates a signal Line conflict transmitted by a low level on line 29, which causes the generator 16 to start and the signal to pass through the lines 30 Collision 4.

The end of any transmission station in a common line 2 communication, t, e. Removing signal 22 from the signal line Transmission resolution also causes the detector 14 to momentarily triggered and the signal transmitted to line 30 Collision, perceived by stations 4, as a successful completion of the transmission to line 2 and device operation 1 confirmation. At the same time, detector 4 responds to the falling edge Signal transmission resolution and generates on line 29 a signal Line conflict equal in duration to 9-15

5 bit intervals, i.e. 900-1500 not, which causes all stations 4 connected to device 1 to transmit a collision signal. This function is necessary to control the operation of the latching mechanism. In this case, the Collision signal is perceived by stations 4 as a test signal. Unambiguous response of stations to a signal A collision as a test or a real conflict in a common link 2 is achieved by the demands on the transmission system that uses the proposed device, i.e. the minimum duration of the transmitted information packet must be twice the propagation time of signals between the end stations of the system. A station can start a transfer only if there are 2 transmissions of other stations in the line, etc. according to the requirements for systems with random multiple access, carrier sensing and collision detection using a common pshna communication channel (standard 1 EE 802.3). Fulfillment of these requirements allows the stations to identify a Collision signal as a test one if Station 4 at the time of receiving the Collision signal is not transmitting, and as a signal of a real line conflict, if at the time of receiving the signal

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Collision station transmits on common link 2

Channel transmitter 11 (Fig, 2) works as follows.

In the initial state, i.e. in the absence of transmissions from station 4, on lines 22-25, high levels of S keys 32, 37 and 40 are set off. When transmitting information From any station 4 on lines 22, a low level signal is set to enable transmission. Since line 25 is set to a high level, which is inverted by inverter 39, the information supplied by line 23 to the input of the OR element 38 is passed to the control input of the switch 32 and causes current to flow into the common link 2 from the power source E. through a resistor 31, crc 32 and diodes 33 - 35, corresponding to the sequence of transmitted data (low and high levels). In the case of simultaneous transmission from two or more stations connected to device 1, line 25 will be set to low - Signal level Conflict in the block, which will lead to installing a high level at the output of the HE element 39, prohibiting the passage of information through the OR element 38, the output of which is set to high, turning off the key 32 and turning on the key 37 "To the common line 2 connection from the power source -E through a resistor 36, key 37 and diodes 33 - 35 will be supplied with a current level detected by the devices as the presence of two or more transmissions in the line 2, e, as a situation. Collision. In the case of an attempt to transfer to the general communication line 2 an information packet with a duration longer than the maximum (defined by the proto on the line 24, the Long Packet signal will be set to a low level, causing the key to turn on. 40 and regardless of the state of the keys 32 and 37, the channel transmitter 11 will be disconnected from the common link 2 of the communication by the reverse biased diodes 33-35,

Switch 9 () works as follows.

Information arriving via line 18 can be supplied to the output of switch 9 (line 23) through AND 42 only according to the condition of installation on the low logic level 21.

Node 10 (Fig, 4) works as follows

In the initial state, t, e, in the absence of transmissions from station 4, high levels are set on lines 20, high levels on lines 21, low levels on inverse outputs of elements 43, low levels on outputs of elements

NI-44 44 - low levels, on lines 22 and 25 - high levels. When transmitting information from station 4, line 20 will receive a low level Transmit signal i, which will cause switching of the IZH 43 / element and set a low level on line 21 and a high level on the inverse output of the OR 43- element. This will block the remaining elements OR 43 and setting a low level at the output of the element OR NOT 46, t, a, setting the signal to transmit the transmission to line 22; In the case of an attempt to transmit by the station 4 when the station 4 starts transmitting to the line

20 low level will be installed

Signal Transmit J, However element.

OR 43i will be locked and will change

its state, with inverse output

element OR 43i low level is fed to the input element OR NOT 44i. Therefore, setting a low level on line 20; will lead to an OR-NOT 44j element triggering and setting a high level at its output, which is fed to the input of the OR-NOT 45 element. The OR-NE 45 element output is set to a low level, i.e., on line 25, the Conflict in the block signal is set. Transmit signals 1 Transmit 1 and Transmit j with line 20; returns node 10 to its original state,

The transmission detector 8 (FIG. 6) operates as follows.

In the absence of information sequence on the primary winding. transformer 48 (line 17), the following potentials are set: 10.2V - resistor 55 - direct comparator input 53 - resistor 56 - resistor 57 - inverse comparator 53, In this case, a lower potential is set at the direct input of the comparator 53

than the inverse of the input. Therefore, the output 6 of the comparator 53 is set to level 1 and the output 7 level O, which is fed through the resistors 58 and 59, respectively, to the inputs

element 54, whereby a level I is established on line 20, which corresponds to the absence of a receive signal,

At the forward output of comparator 54, a level O is set, the inputs to the positive feedback circuit, consisting of diodes 67 and 68 and resistor 60, diode 68 is closed and diode 67 is open. The offset of the inputs of the comparator 53 is determined by the current flowing through the circuit: 10, 2V - resistor 60 - diode 67 - comparator input 53 - resistor 56 - resistor 57 - comparator input 53, The circuit is set to a steady state. In order to bring the circuit out of this state, the inverse input relative to the direct input of the comparator 53 must have a negative signal, at a magnitude larger than the constant offset between the inputs. When the information sequence appears on the primary winding of the transformer 48 (line 17), the first negative voltage drop on the secondary winding of the transformer 48 will cause a change in potentials at the inputs of the comparator 53. Now the potential of the inverter 53 will be lower than at the direct input. The comparator 53 switches: on the inverse output, the level is O, and the direct output is level 1, while the capacitor -66 is charged through the output impedance of the open emitter follower on the direct output of the comparator 53, the comparator 54 switches with a delay, the resistor 58 and 59 and the codensor 65, after which the line O is on line 20, and the forward output of the comparator 54 is level 1. In this state, the diode 68 opens and the diode 67 closes, the current through the circuit : 10, 2V - resistor 69 - diode 67 - bo resistor 56 not even leaking and

In this state, the capacitor 66 cannot be discharged through the output resistance of the closed emitter follower, its discharge time is determined by the value of the resistor 62 and for all this time the comparator 54 maintains state 1 on the direct output and About on the inverse output. This time is called the delay time of the detector 8 and is equal to - 200 n. If during this time the primary winding of the transformer 48 (line 17, fig 5) and, therefore, the inverse input of the comparator 53 comes a new negative pulse of the information sequence, then the capacitor 66 will quickly charge again

and the comparator 54 will remain in the same position.

The level O at the inverse output of the comparator 54 is a Receive signal coming in line 20 to

input node 10,

The detector 14 performs the carrier detection function when receiving the information sequence from the common link 2, the situation detecting function Collision in the common link 2 and the testing function of the collision detection mechanism after each transmission made by the device 1, and operates as follows

in the manner (FIG. 7),

The emitter follower on transistor 75 and its discrete components associated with it: resistors 83, 84, 90 and capacitors 105, 106, 108 form a low-pass filter circuit. At the filter output, the voltage level is equal to the average value of the signal in the common link 2, From the output the filter signal is fed to the forward input of the comparator 69 and through the resistor 96 to the direct input of the comparator 70, and is compared with two reference voltage levels. One reference voltage level is used to determine

DC voltage between 50 availability of information sequence-inputs of comparator 53 disappears, between these inputs there is only an information sequence coming from the secondary winding of the transformer 48 (line 19). At the end of 55 negative voltage drop on the secondary winding of the transformer 48 by VTS voltage which switches the comparator 53, t, e, on its strength in the common link 2, and the other reference voltage level - to determine the situation Collision, t, e, the simultaneous presence of 2 and the communication of two or more of the transmissions. The reference levels are respectively supplied to the inverted inputs of the comparators 69 and 70. These two reference voltage levels are set by precision and the difference of the information sequence

the common reference level of the voltage to determine the situation Collision, t, e, of the simultaneous presence in the link 2 of two or more gears. The reference levels are respectively supplied to the inverted inputs of the comparators 69 and 70. These two reference voltage levels are set by a precision current source consisting of the transistor 81 and the compensation circuit of the transistor 80, the base of the transistor 81 is connected to the power supply - 5.2V, and its emitter - with power — 10.2V through resistor 10; Resistor 101 is highly accurate; the voltage across it is set by the current of the transistor 81. The source of the reference levels is tuned by a resistor 10

The transistor 80 is a similar current source with an emitter resistor 100 to obtain the same emitter current.

Transistor 74 has a current source that sets the current for transistors 75 and 7fi. Transistor 76 is a current source whose emitter through high-precision resistors 86 and 95 is connected to the collector of transistor 81 and serves to stabilize the current in this circuit,

The signal from the emitter of transistor 75 is provided by filtering the sum of the signals from the common link and the collision test signal from the collector of transistor 78 and is compared with the indicated reference voltage levels

In the absence of information sequence in the common link 2, a lower potential is set at the inverse input of the comparator 69 than at the direct input. Accordingly, level 1 is set at the direct output of the comparator 69, and O at the inverse output arrive at the inputs of the buffer amplifier 71. According to this, the output of the buffer amplifier 71 is set to level 1, which is fed to the input of the interface transmitter 15 via line 27, which corresponds to the reception signal removal.

When the information sequence appears in the common link 2, a lower potential is established at the direct input of the comparator 69 than at the inverse input. The comparator 69 is switched, the O level is set at the direct output, and the level 1 is at the inverse output, which respectively arrive at the inputs of the buffer amplifier 71. Accordingly, the O level is set at the output of the buffer amplifier, which corresponds to the signal received at the input interface transmitter 15 on line 27.

In the absence of a situation, a collision in the common link 2 at the inverted input 12 of the comparator 70 is set at a lower potential than at the direct input. In accordance with this, the direct output of the comparator VO is set to level 1, and the inverse output is set to level O,. which are fed to the inputs of the buffer amplifier 72, the output of which is set to level 1, which is fed to the input of the generator 16 through line 29, which corresponds to the setting of the signal Collision in the line. The element 73, the transistors 77 and 78, the resistors 88-94 and the capacitor 107 implement the function of testing the collision detection mechanism after each transmission made by the device 1 to the common link 2.

The interface information transmitter 15 performs the function of transmitting the information sequence through the multiplexer interface and operates as follows (FIG. B).

Resistor 115 and capacitor 125 filter out high-frequency harmonics from the received information sequence. The transistor 114 is a secondary repeater providing low output impedance for a high-pass filter consisting of a capacitor 126 and a resistor 117, the emitter of transistor 1I4 is connected to the forward input of amplifier 110. The outputs of amplifier 110 are connected respectively to the inputs of buffer amplifier 111, Output of buffer amplifier connected to the input of the buffer amplifier 112, as well as to the output of the I4 detector (line 27, buffer amplifier 71, FIG. 7). Since this is emitter-coupled logic, i, e, the output of any of the amplifiers 71 or 111 is high, their overall yield is high (level 1). Consequently, in the absence of an information sequence, the output of the amplifier 71 is set to level 1 (output of the second detector 14, line 27, Fig.7), which turns off the output of the buffer amplifier 111,

When the information sequence appears in the common link 2, the output of the second detector 14 (amplifier 71, line 27) is set to level O, which corresponds to the setting of the Receive signal. From the output of the channel receiver 13 (line 26) the information sequence passes through the path described above: transistor 114 — capacitor 126 — software amplifier — amplifier 111 — amplifier 112 — OR element 113. From the outputs of the OR element 113, the information sequence is fed to the primary winding of the transformer 128 Differential the signal from the secondary winding of the transformer 128 is fed to the information input station 4.

Collision signal generator 16 performs the signal transmission function Collision through the multiplexer interface and operates as follows (FIG. 9).

On the OR 129 element, the capacitors 134, 135, the inductance 137 and the resistor 131, a controlled oscillator is built according to the circuit with a phase-shifting back coupling, tuned to a frequency of 10 MHz.

In the initial conditions at the input of the element OR 129, the line is set to level 1, which is a prohibition to start the generator.

The generator starts when the low logic level 29 is installed.

Claims (1)

Invention Formula A device for interfacing subscriber stations with a local network communication line, comprising a transmitting unit consisting of a channel transmitter connected by a lock input to a timer output, and a first transmission detector connected by an input to a first output of the first interface receiver whose output is an input of the device for connecting to the information output of the first subscriber station, a receiving unit consisting of a channel receiver, an output connected to the information inputs of the collision detector and the first int A front-end transmitter, the enable input of which is connected to the first output of the collision detector, the second output connected via the first collider driver to the output 1437872 12 five 0 device to connect to the input of the collision signal of the first subscriber station, and the output of the first interface transmitter is the output of the device to connect to the information input of the first subscriber station, the output of the channel transmitter connected to the input of the channel receiver is the input-output of the device to connect to local network, characterized in that, in order to expand the class of tasks of the device, N-1 interface receivers, N-1 transmission detectors, which mmutator and priority node, and in the receiving unit - N-1 interface transmitters and N-1 collision shapers, the input of the i-ro transmission detector (i 2,. К) is connected to the first output of the i-ro interface receiver, whose input is 5 input device to connect to the information output of the i-th subscriber station, the output of the channel receiver and the first output of the collision detector are connected respectively to the information and enable inputs of the i-ro interface transmitter, the output of which is the output of the device for for prison to the data input of the i-th subscriber station, the second output of the collision detector through the i-th formation. The collision signal is connected to the output of the device to connect the input of the collision signal - the i-th subscriber station, the first to the N-th information inputs of the switch are connected respectively to the second outputs from the first to the N-th interface receivers, and the output to the g information input channel transmitter, the enable input of which is connected to the enable input of the collision detector, the timer input and the first output of the priority node, the second output and a group of outputs connected respectively to the control input channel Nogo transmitter group and the actuating switch inputs, the outputs of the first through N-th transmission detectors are connected to the input node priority group. five 0 0 five  -, F1 / 8. .f DD CSD 33 3 yf -kw . FI.5 as Y9V1Sh D m -ia2vw .2i -S2V t FIG. 7 17 125 f / 5U "7 $ 0 // AG - / L2 29 Fiz.v -5.ZV -5.2 / CPUS. 9