SU1183973A1 - Interface for linking terminals with communication channel - Google Patents

Description

The invention relates to computing and can be used in automated systems for collecting and processing information, in particular, in automated systems. designing for, providing connection of remote terminals with computers.

The aim of the invention is to improve the performance of the device due to the introduction of the possibility of automatic repetition of the transmission of the character and automatic messages to the subscriber about the results of receiving from him the character.

Figure 1 presents the block diagram ^; the device in figure 2 is a functional diagram of the transceiver; in fig. 3 and 4 - timing charts of the device in the modes of transmission and reception of characters, respectively.

The device contains (FIG. 1) terminal 1, transceiver 2, group of elements AND 3, element OR-NOT 4, triggers 5 and 6, element NOT 7, elements AND 8-12, element OR 13, channel 14 of communication.

Information is exchanged between the terminal 1 and the subscriber connected to the communication channel using the following algorithm.

The terminal issues a symbol for transmission to the subscriber, the subscriber receives this symbol and reports the result of the reception. If the received symbol is not distorted, in the subscriber's reply message, the most significant digit is ϋ 8 = 0, if

> the character received by the subscriber is distorted, then О 8 = 1, the device automatically repeats the transmission of the character distorted in the communication channel.

When the terminal receives a symbol transmitted by the subscriber, the response message to the subscriber is transmitted by the device automatically, without the participation of the terminal. In this case, if the received symbol is distorted, in the response message, the high-order digit T 8 = 1, if the symbol is not distorted - T 8 = 0.

Terminal 1 is a. display module with key input device information and prev. assigned to pre-process information at the place of its occurrence (operator’s workplace).

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Element OR NOT 4 is connected by inputs to transceiver 2 and is intended for. trigger trigger lock 5.

5 The latter is intended for the formation of the 3 PR signal (reception request). When transmitting information by the terminal 1, the inclusion of the trigger 5 is blocked by the 0P signal (the end of the transmission).

Trigger 6 is designed to generate an OP signal, and by the signal of the VP terminal (to perform the transfer) it is turned off and set to the initial state 0P = 1, when it receives a confirmation from the subscriber about the correct reception of the symbol transmitted by the terminal 08 = 0.

Element NOT 7 blocks installation

20 trigger 6 in the initial state

with ϋ.8 = 1, when the character transmitted by the terminal was distorted in channel 14.

Element And 8 is connected to the inputs of the trigger 5 and the control output

25 PR (accept) terminal 1. At the output of the element And 8, a signal is generated by which the device sends to the subscriber a response message about the correctness of receiving information from it.

30 Element And 9 ensures that trigger 6 is reset to the initial state by the DPR signal (data received) with ϋ 8 = 0.

Element AND 10 with its own inputs under $ 3 of the keys to the output of the element OR NOT 4, to the output 0P of trigger 6 and to the output of the transceiver DPR. It is designed to enable trigger 5 when receiving an undistorted symbol, re 40 given by the subscriber.

Element 11 is designed to

signal generation, which sends a response message to the subscriber when a distortion is detected

45 received information in the communication channel when 0111 = 1.

Element And 12 is designed to generate a signal by which the device re-transmits a symbol of the symbol when ϋ 8 = 1.

The transceiver 2 contains (figure 2) the element 15 of the serial I / o triggers 16 and 17, shapers 18 and 19 ,. optocoupler

55 receiver 20, generator 21, counter-separator 22, switch 23.

Transceiver 2 is designed to convert parallel3 1183973 · 4

code of a symbol into a serial one and outputting it to communication channel 14, as well as for receiving in a serial form a character from a communication channel and converting it into a parallel code. In addition, the transceiver analyzes the information received from the channel for accuracy and generates an OR (error) signal.

As an element 15 serial I / o can be used, for example, LSI type G-136.

The device works as follows. 15

When the power is turned on, terminal 1 generates an RSB initial setup signal (general reset) in the form of a pulse.

The signal OSB transceiver 2 and triggers 5 and 6 are set 20

in the original state. At the same time on the direct output of the trigger 5 signal.

The PDL (request for reception) is absent, and at the direct output of trigger 6, a signal is generated for the end of the transmission ²⁵ 0P = 1.

In the mode of transmitting information from the terminal to the remote subscriber, the device operates as follows. thirty

The terminal on its information outputs connected to the inputs T1-T7 of the element 15, sets the character code to be transmitted to the communication channel. The control signal is generated at the control output (35).

Signal VP trigger 6 switches to a state in which 0P = 1. In addition, the signal. VP on the 40th output of the element OR 13 forms a signal of the ZBR (loading of the buffer register). It should be noted that the duration of the signal VP should be longer than the repetition period of the sync-45 timing pulses F of the transceiver 2, received using the generator 21, the counter-divider 22, the switch 23.

ZBR signal comes to input 50

trigger 16, to the other input of which sync pulses F are received. At the output of trigger 16, a low-level signal is generated, which records the character code at 55 element 15.

When you turn off the signal VP, at the output of the trigger 16, a high level signal is generated, on the front of which the element 15 transforms and outputs the recorded character code in a sequential form to the output TO. The signal from the output of the TO through the driver 18, which is a current amplifier, is fed into the channel 14 connection.

In this mode, when receiving from the subscriber a response message about the correctness of the reception of the symbol transmitted by the terminal, the most significant bit

the response symbol will be zero. In this case, the DPR signal (data received) is fed to the input element I 9, at the other output of which there is a single signal, since ϋ8 = 0, and sets trigger 6 to its original state. A single signal OP from the output of the trigger 6 informs the terminal 1 of the completion of the transmission of the symbol, i.e. The terminal may issue the next symbol for transmission to the communication channel.

If, in the subscriber response symbol, the most significant digit is ϋ8 = 1, this means that the symbol transmitted by terminal 1 has been distorted in the communication channel and the subscriber requests to repeat the transmission.

In this case, without the intervention of the terminal, the symbol that is distorted in the channel is repeated.

Repeat as follows.

The signal from the transceiver DPR when ϋ 8 = 1 on the element And 12 generates a signal, which through the scheme OR 13 carries out the formation of the ZBR. In this case, the code of the transmitted symbol is re-recorded, and then the process of transmitting it to the communication channel 14 occurs in a similar way.

When O 8 = 1 element And 9 is blocked by the output signal of the element NOT 7, therefore, at the output of trigger 6, there is no signal OP, allowing the terminal to increase the next character, i.e. on the information outputs of terminal 1, the information does not change.

Thus, in the mode of transmitting information from the terminal to the remote subscriber, the proposed device, in comparison with the known one, has greater productivity for the account of the organization of automatic

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Repeated transmission when the symbol is distorted in the communication channel and greater transmission reliability due to the fact that the OP signal informs the terminal that the transmission of the symbol is complete, i.e. The terminal transmits the next character only when an acknowledgment is received from the remote subscriber.

In the mode of receiving information from a remote subscriber, the device operates as follows.

Information from the subscriber in the form of a sequence of pulses received from the channel 14 to the receiver input photocouple performing a galvanic isolation from the subscriber, and further through the generator 18 is supplied to the serial input of element 15. A strobe inputs £ ₀ {.elementa 15 clock pulses are fed F . Low levels of signals and BRO BIS provide connection to the output of information signals ϋ1-ϋ8, signal PD, "flags"

04 00 D P, where 04 is an error in the reception of parity, 00 D is an error in the reception according to the format of the word.

Element 15 converts the serial code of the symbol and generates at the outputs ϋ1-ϋ8 the parallel code of the received symbol, the signal PD, a sign of error if the information in the communication channel has been distorted. The signal PD trigger 17 generates a signal DPR with a duration equal to the repetition period of the clock pulses f. In the case of receiving information from the subscriber without an error (0111 = 0), the DPR signal through the AND 10 element sets the trigger 5 to one state, since in this mode 0P = 1 and the output of the OR-NOT 4 element is also a single signal.

From the output of the trigger 5 to the control input of terminal 1 receives the signal BRA (receive request).

On this signal, the terminal, if it is ready to receive a symbol, generates a PR signal (receive a symbol). The duration of the signal PR is greater than the repetition period of the sync signals, f.

Information from the outputs of the transceiver 2 is gated by the PR signal and through the elements And 3 enters the information inputs of the terminal.

The signal PR, passed through the elements of the OF, OR 13 at the output of the element OR 13, a signal ZBR, on which there is a transfer confirmation of the correctness of the character from the subscriber.

When you turn off the signal PR output signal element And 8 sets the trigger 5 to its original state, which means the device is ready to receive the next character.

When receiving a symbol from the communication channel with an error, the transceiver generates an error signal 0SH = 1. In this case, the element And 10 is blocked by a low level signal from the output of the element OR NOT 4 and the signal DPR does not affect the trigger 5, leaving it in its original state, in which the signal BRA is not generated.

The signal DPR, passed through the element And 11 to the input element OR 13, a signal ZBR, which is sending a message to the subscriber about the error. Information about the error in reception is set by transceiver 2 in the eighth digit of the transmitted symbol. This is done by connecting the signal 0Ш = 1 to the input T 8 of element 15. ·

It should be noted that in the mode of transmitting information to the subscriber, when 0P = 0, the And 10 element is blocked, therefore, when receiving a confirmation from the subscriber to the symbol transmitted by the device, trigger 5 is not included. Figure 4 shows the timing diagram of the device in the mode of receiving information from the subscriber.

Thus, in the receive mode, the proposed device has greater performance due to the fact that the error handling algorithm for receiving information is performed automatically, without interrupting the terminal. In addition, in the proposed device, the reliability of the received information is increased due to the fact that the device informs the remote subscriber about the results of receiving information, which allows to exclude the loss of information in the case of a busy terminal or in case of distortion of information in the communication channel.

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Claims (1)

A DEVICE FOR CONNECTING TERMINALS WITH A COMMUNICATION CHANNEL, containing a transceiver, a group of AND elements, an OR-NOT element, the first and second triggers, the first and second elements AND, the first input of the first element AND connected to the input signal of the device Accept, and the second input is connected to the output of the first trigger, the output of the second element And is connected to the first input of the second trigger; the information outputs of the device are connected to the outputs of the AND elements, the first inputs of which are connected to the information output of the transceiver, info mation input of which is connected to the information input device and the signal output "error" and controlling the discharge - to first and second inputs of OR-NO element, characterized in that, in order to increase its productivity, it introduced a third ,. the fourth and fifth elements are AND, the OR element and the element are NOT, and the element input is NOT connected to the transceiver's control discharge, and the output to the first input of the second And element, the second input of which is connected to the data output of the transceiver and the first inputs of the third , the fourth and fifth element And, the second inputs of which are connected respectively with the output of the element OR NOT, with the output signal "Error" of the transceiver and the output of the control digit of the transceiver, and the outputs of the third, fourth and fifth element And are connected respectively to the installation input of the first trigger and to the first, second inputs of the OR element, the third and fourth inputs of which are connected respectively to the device's Run signal input, to the first reset input of the first trigger and the output of the first And element, and the output to the input signal "download" transceiver input reset which is connected to the second reset input of the first trigger, the second installation input of the second trigger and the device reset input, the reset input of the second trigger is connected to the device's input signal, and the output to the third input of the third element And the output of the device's end signal , the output "Request reception" of the device is connected to the output of the first trigger, the input signal "Accept" of the device is connected to the second inputs of the AND elements of the group, the control discharge input of the transceiver is connected to the output signal "Error" n iemoperedatchika. zi "1183973 eleven