BG65075B1 - Method and device for two-way data exchange on a current circuit of a two-wire line - Google Patents

Abstract

The invention relates to a method and device which increases the speed of the two-way exchange of information within one cycle of the supply voltage. The device is simplified and reliable. In it the second winding of a mains transformer (5) is connected top one of the ends of a logical diagram (2), with a former of output current pulses (3) and with a converter of inlet current pulses (4) into voltage ones. Diagrams (2, 3 and 4) have standard connections to the serial interface (1) of the main station (I), and the secondary winding of the mains transformer (5), the second leads of the former (3) and the converter (4) are connected along a two-wire line (6) with a subordinated station (II).

Description

(54) METHOD AND DEVICE FOR BILATERAL DATA TRANSFER ON A DUAL CIRCUIT

Field of application

The invention relates to a method and device for two-way data exchange on a two-wire circuit between remote digital devices and can find application for the exchange of information between information, measuring and control devices (computers, microprocessor measuring systems, controllers for object management) and others·)·

BACKGROUND OF THE INVENTION

A method is known for performing two-way data exchange between a master and a slave station on a two-wire line with alternating sine wave voltage, in which, using the polar sign recognition signal, the transmission of information from the master station to the slave is performed by single positive pulses of a duration, close to the half-life of the supply voltage, and the reception of the information sent from the slave station by a combination of single negative pulses with duration. Each positive impulse is formed within one positive half-life of the supply voltage and each negative one is formed within the negative half-life (viewed from the side of the main station). Transmission is performed by a special protocol, and special algorithms are used to recognize the received information [1].

A device for carrying out this method is known, consisting of a main station with a sine wave generator, a special interface with an output to a transmitter with a coding device and an input from a receiver with a decoding device. The master station is connected via a two-wire line to a slave station including a special interface, with an output to a transmitter with a coding device and an input from a receiver with a decoding device [1].

A device for multipoint connection of more than one slave station to the main station by means of a special multiplexer for the three lines of the standard serial interface is known [2].

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for two-way data exchange over a two-wire line using a 50 Hz mains voltage as the supply sinusoidal voltage. Within one supply voltage period, by controlling current through the line, 1 byte (8 information bits and 2 service distances up to 4 km) are transmitted and received to 4 bytes (32 information bits and 8 service distances up to 1 km) at standard exchange rates of 2400 to 9600 Kbits / s. During the positive half-life of the supply voltage, the data exchange is from the main to the slave station, and through the negative - back. During transmission, the control of the supply sinusoidal voltage is ensured in order for the transmission to be carried out at a sufficient level of the positive supply voltage and reception at a sufficient level of the negative supply voltage (within a period of 20 milliseconds). Transmission from the master and slave stations is carried out by a constant current value of 10 to 30 mA at one logic level transmit (eg “0”) and 0 mA at the second logic level transmit (eg “1”). The data transmission and reception protocol allows direct use of standard serial interfaces on modern computers and microcontrollers.

The advantages of the proposed method are its simplicity, the increased speed of bilateral exchange of information within a single period of the supply voltage, the application of a standard data exchange protocol.

The apparatus implementing the method according to the invention comprises a main station with secondary power supply of a network transformer, a standard serial interface with two sets of output / input signals. One pair of signals is connected to a logic block for controlling the supply voltage and the other to the output current impulse generator and the output current converter of the voltage impulse respectively. The master station is connected via a two-wire line to a slave station, also including a standard serial interface with two sets of output / input signals. One pair of signals is also connected to a logic unit for controlling the supply voltage, and the other to the output current impulse generator and the output voltage converter output, respectively.

The advantages of the device are its simplicity and reliability - it uses a simple mains transformer instead of a standalone sinusoidal oscillator for increased frequency, eliminating the need for a complex logical block to convert the transmitted and received data. An elementary logic block is used to control the mains voltage and generate the signals required by the standard serial interface protocol.

Explanation of the attached figure

Attached figure 1 is a block diagram of a device for carrying out the method.

Examples of carrying out the invention

According to FIG. 1, a logic unit 2, an output current generator 3, and an input current converter 4 are connected to one end of the secondary coil of the network transformer 5. Blocks 2,3 and 4 have the standard connections required by the main digital serial interface 1 device. The second end of the secondary winding of the network transformer 5, as well as the second terminals of the shaper 3 and the transducer 4, are connected via a two-wire line 6 to the slave station adapter, which is in the same circuit.

The operation of the device is as follows. If a transmit request (RTS) signal is received from the serial interface 1 of the main station I, the logic unit 2 waits for the positive voltage period to occur and then sends a CTS (transmit permission) signal to the serial interface

1. The latter transmits by standard protocol up to 4 bytes of the TxD bus, which are converted to the shaper 3 in current pulses (eg logic level “0” at 10-30 mA, logic level “1” in 0 mA) and are transmitted according to the two-wire line 6 to the converter 4 of the slave station adapter. The converter 4 converts the current pulses into voltage and according to the standard protocol they are transmitted via the RxD bus to the serial interface 1 of the slave station II. Generally, transmission from Main Station I is made between the second and eight milliseconds of the mains voltage period when it is positive and with a value greater than 0.6 of the maximum value. The negative half-life for the main station I is positive for the slave station adapter. After receiving the information, the serial interface 1 of the slave station II submits a transmission request signal (RTS), the logic unit 2 waits for the positive voltage period (negative if viewed from the side of the main station) and then sends a signal CTS (Transmission Permission) to Serial Station Serial Interface 1. The latter transmits, by standard protocol, up to 4 bytes of the TxD bus, which are converted to the current generator 3 into current pulses and returned via the two-wire line 6 to the converter 4 of the main station adapter I. Converter 4 converts the current pulses into voltage and according to the standard protocol enter the RxD bus to the serial interface 1 of the master station.

With sufficient speed of data processing in digital devices, it is possible to exchange each other twice from one (at two-wire length up to 4 km) up to four bytes (at two-wire length up to 1 km) during each period of the mains voltage.

The main station is the leading information exchange. In most cases, multiple point connections of multiple slave stations to one master station are required by multiplexing the lines to the slave stations, but this does not fundamentally change things.

In FIG. 2a shows the manner and type of impulses generated by the method described in [1].

For comparison of FIG. 26 shows the method and type of impulse generation in the proposed method. Within one supply voltage period (eg 50 Hz) 50 bits / s are transmitted and received at [1]. In the proposed method, for a standard rate of exchange of 9600 bits / s between the serial interfaces of the master and slave stations, 40 bits can be transmitted and received, over 2000 bits / s, over a period of mains voltage. s.

Claims (2)

Claims 1. Shevkoplyas BV Microprocessor Structures - Solution Engineering. Moscow, “Radio and Communication” - 1993 (p. 18: Patent 2.212.954 A, UK, MKI G 06 F 1/00). 1. A method of bilateral data exchange over a two-wire circuit between a master and slave stations using the polar sign recognition feature, characterized in that 1 to 4 bytes of information are transmitted from the master station, positive half-life of the supply voltage, which is a 50 Hz mains voltage, and information from the slave station of 1 to 4 bytes is received during the negative half-life of the supply voltage, the exchange being synchronized with the forward Leno minimum level of mains voltage. 2. A device for bilateral data exchange on a two-wire line circuit intended for carrying out the method according to claim 1, comprising a main station (I) connected via a two-wire line to a slave station (II), characterized in that the secondary the coil of the mains transformer (5) supplying the main station (I) is connected at one end to a logic block (2), with an output current impulse generator (3) and with an input current impulse converter (4), as blocks (2, 3 and 4) have the standard connections required by se main interface (I) of the main station (I) and the other end of the secondary winding of the mains transformer (5), as well as the second terminals of the shaper (3) and the converter (4), are connected along the two-wire line (6) to the slave station (II), which has the same scheme. Attachment: 2 figures Literature 2. Shevkoplyas BV Microprocessor Structures - Solution Engineering. Moscow, “Radio and Communication” -1993 (p. 11: European Patent EP 0.359.064.A2. MKI G 06 F 13/00).