SU1264363A1 - Device for duplex transmission of digital information via two-wire communication line - Google Patents

Abstract

The invention can be used in local networks to automate 1 control systems. Noise immunity is detected. The signal to be transmitted goes to transmitting amplifier I and to element 3 EXCLUSIVE OR. From the transmitting amplifier 1, the signal comes directly and through the current comparator (CT) 2 to the device inputs-outputs. CT 2 sets the value of the received signal. At the same time, the presence of a current indicates a counter-transmission of a signal of opposite polarity with respect to the transmitted data of the device, and the absence of a signal indicates a counter-transmission of a signal of the same polarity. The formation of the received signal is carried out by the element 3 EXCLUSIVE OR, which inverts the value of the parcel from the input of the transmitting amplifier 1 in the presence of current in the communication line and does not invert in the case S the absence of current. The introduction of CT 2 and element 3 EXCLUSIVE OR provides (looses the galvanic isolation of the circuit receiving information from the communication line and increases the noise immunity of communication. 2 Il. ND O) 4 OQ One CO

Description

The invention relates to telecommunications and can be used in local communication networks of automated control systems.

The purpose of the invention is to increase the noise immunity of communication.

Figure 1 presents a structural electrical diagram of a device for duplex transmission of digital information on a two-wire communication line; on figa, <$ - schematic diagrams of the current comparator.

A duplex device for transmitting digital information on a two-wire communication line contains a transmitting amplifier 1, a current comparator 2, and an EXCLUSIVE OR element 3. The current comparator (Fig. 2a) includes a diode bridge 4, a diode-transistor optocoupler 5 and a resistor 6. In addition, the current comparator (Fig. 26) consists of two diode-transistor optocouplers 7 and 8 and a resistor 9.

A duplex device for transmitting digital information on a two-wire communication line operates as follows.

The signal to be transmitted is fed to the input of the transmitting amplifier I and, through the current comparator 2, to the device inputs and outputs connected to a two-wire symmetric or asymmetric communication line. In the latter case, the first input-output of the transmitting amplifier 1 is connected to a common wire. The opposite end of the communication line is equipped with a similar device.

The selection of the values of the received signal is carried out using the element 3 EXCLUSIVE OR and the current comparator 2, which registers the presence or absence of current of any direction in the communication line. In this case, the presence of current indicates oncoming transmission from the opposite end

As a current comparator 2, one of the circuits shown in FIGS. 2 o and δ can be used. In the current comparator shown in Fig. 2a, 5, the diode bridge 4 allows, with the help of the diode of the optocoupler 5, to detect the flow of current in any direction in the communication line, and the transistor of the optocouple 5 connected to the power supply 10 generates a logical signal 1 at the resistor 6 the presence of current in the communication line and a logical O signal in its absence.

The current comparator according to the circuit of FIG. 26-15 contains a resistor 9 connected to a power source and two diode-transistor optocouplers 7 and 8, moreover, their light-emitting diodes are connected in parallel to the communication line break, and the transistor outputs are combined, forming the comparator 2 output current. This circuit generates a logic 0 signal in the presence of current in the communication lines and a logical 1 signal in the absence of it, i.e. the received signal receives a logical inversion.

Thus, the choice of the current comparator circuit (from the given 30 or some other) depends on the specific requirements for the device and on the used elemental base.

Compared to the prototype, the device for duplex digital information transmission over a two-wire communication line provides galvanic isolation of the information receiving circuit from the communication line, allows the use of 40 more noise-resistant symmetrical lines (twisted pairs), does not require individual adjustment *, which generally leads to increased noise immunity communication.

Claims (1)

FIG. 1 The invention relates to telecommunications and can be used in local area networks of automated control systems. The purpose of the invention is to increase the noise immunity of communication. Fig. 1 shows a structural electrical circuit of a duplex digital information transmission device over a two-wire communication line; in Fig.20.5, the current comparator circuit diagrams. A duplex digital information device over a two-wire communication line contains a transmitting amplifier I, a current comparator 2 and an EXCLUSIVE OR element 3. The current comparator (Fig. 2aj includes a diode bridge 4, a diode-transistor optocoupler 5 and a resistor 6. In addition, the current comparator (Fig.26) consists of two diode-transistor optocouplers 7 and 8 and a resistor 9. A device for duplex transmission of digital information over two wires The communication line operates as follows: The signal to be transmitted comes to the input of the transmitting amplifier 1 and through the current comparator 2 to the device inputs-outputs connected to a two-wire balanced or unbalanced communication line. In the latter case, the first input-output is transmitted its amplifier 1 is connected to the common wire. The opposite end of the communication line is equipped with a similar device. The received signal is displayed using the EXCLUSIVE OR element 3 and the current compiler 2, which detects the presence or absence of current of any direction in the communication line. In this case, the presence of a current indicates a counter transmission from the opposite end of the communication line of a signal of opposite polarity with respect to that transmitted by this device. The absence of current in the communication line is a sign of the transmission of a signal of the same polarity to this device. The formation of the received signal is performed by element 3 EXCLUSIVE. ALS OR, inverting the value of the parcel from the input of the transmitting amplifier 1 in the presence of current in the communication line and not inverting in the absence of current. 631 As the current KOMnapatopa 2, one of the circuits shown in Fig. 2 ib can be used. In the current comparator shown in Fig. 2a, the diode bridge 4 makes it possible to detect, using the diode of the optocoupler 5, the flow of current of any direction in the communication line, and the transistor of the optocoupler 5 connected to the power source on the resistor 6 generates a logical 1 signal at the presence of a current in the communication line and a logical O signal in its absence. The current comparator according to the scheme of Fig. 25 contains a resistor 9 connected to a power source and two diode transistor optocouplers 7 and 8, and their light-emitting diodes are included in the break of the communication line anti-parallel, and the transistors of the transistors are combined to form the output of the comparator 2 current . With this scheme, you generate a logical O signal when there is a current in the communication line and a logical 1 signal when it is (No, i.e. the received signal receives a logical inversion. Thus, the choice of the current comparator circuit (from among the given ones or some other) depends from the specific requirements of the device and from the element base used. The device for duplex transmission of digital information over a two-wire communication line, in comparison with the prototype, provides galvanic isolation of the information receiving circuit from the communication line. , allows the use of more robust symmetrical lines (twisted pairs), does not require individual adjustment, which generally leads to an increase in the noise immunity of the communication. Formula of inventions A device for duplex transmission of digital information over a two-wire communication line, containing a transmitting amplifier, whose input is The input of the device, and the first input of the transmitting amplifier is the first input-output of the device, characterized in that, in order to increase the noise immunity of the communication, the following but connected to current comparator and ISKPYUCHAICHEE OR element, the second 312643634 the input of which is connected to the input of the input-output of which is a reducing amplifier, the second input-output, jBTOpbiM input-output of the device, the stroke of which is connected to the first input of which is the output of the current comparator, the current EXCLUSIVE OR. FIG. 2