KR20030039081A - Half-duplex communication system - Google Patents

Abstract

PURPOSE: A half-duplex communication system is provided to transmit and receive signals by using only a transmission cable of two lines without sharing a signal ground terminal between devices. CONSTITUTION: The first terminal portion(210) includes the first differential line driver(211) and the first optical coupler(212). The first differential line driver(211) is used for transmitting a signal to the second terminal(220). The first optical coupler(212) is used for receiving the signal from the second terminal(220). The second terminal portion(220) includes the second optical coupler(222) and the second differential line driver(221). The second optical coupler(222) is used for receiving the signal from the first differential line driver(211) of the first terminal portion(210). The second differential line driver(221) is used for transmitting a signal to the first optical coupler(212) of the first terminal portion(210). A transmission cable(230) is used for connecting the first terminal portion(210) with the second terminal portion(220).

Description

Half-duplex communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and more particularly, to a half-duplex communication system capable of transmitting / receiving signals using two lines of transmission cables without sharing signal ground terminals between devices in performing communication between devices. .

In general, a lot of communication needs to be performed for transmission of signals and data. Such transmission of signals and data may be performed by wire or wirelessly depending on the equipment. At this time, in transmitting signals, data, and the like through a wire, signal ground terminals must be shared between the equipment. However, when a potential difference is generated between two devices, there is a problem that a ground current is generated by the potential difference between the two devices.

As one method for solving such a problem, as shown in FIG. 1, there is a method in which an opto-coupler is not used to share a signal ground terminal between devices. 1 is a block diagram schematically illustrating a configuration of a communication system using a conventional optical coupler.

Referring to FIG. 1, a communication system using a conventional optical coupler includes a first terminal 110 including a first transmitter 111 for transmitting a signal and a first optocoupler 112 for receiving a signal; A second terminal 12 having a second transmitter 121 for transmitting a signal and a second optocoupler 122 for receiving a signal; And a transmission cable 130 for transmitting a signal between the first terminal 110 and the second terminal 120.

In the communication system using the optical coupler, by using the first optical coupler 112 and the second optical coupler 122 in transmitting and receiving signals, the first terminal 110 and the second terminal 120. It does not require sharing of the signal ground between the terminals.

At this time, the first terminal 110 transmits a signal to the second optical coupler 122 of the second terminal 120 through the first transmitter 111, the second terminal 120 is a second transmitter The signal is transmitted to the first optocoupler 112 of the first terminal 110 through the 121. Accordingly, the transmission cable 130 for transmitting the signal between the first terminal 110 and the second terminal 120 has a disadvantage that requires four lines.

On the other hand, when the potential difference between the two equipments, there is another method for using a separate power source as a way to solve the problem that the ground current is generated by the potential difference between the two equipments. As described above, in the case of using a separate power supply for each equipment, additional devices such as a DC / DC converter are required together with the sharing of the signal ground terminal.

The present invention has been made in view of the above circumstances, and in performing communication between devices, a signal is transmitted using a differential line driver in transmitting a signal, and an optical coupler is used in receiving a signal. It is an object of the present invention to provide a half-duplex communication system capable of transmitting / receiving signals using two lines of transmission cables without sharing signal ground terminals between equipments.

1 is a block diagram schematically showing the configuration of a communication system using a conventional optocoupler.

Figure 2 is a block diagram schematically showing the configuration of a half-duplex communication system according to the present invention.

3 is a diagram illustrating a control state in a case of transmitting a signal from a first terminal to a second terminal in a half-duplex communication system according to the present invention.

4 is a timing diagram when a signal is transmitted in the half-duplex communication system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

110, 210 ... first terminal 111 ... first transmitter

112, 212 ... first optocoupler 120, 220 ... second terminal

121 ... second transmitter 122, 222 ... second optocoupler

130, 230 ... Transmission cable 211 ... First differential line driver

213 ... first relay 216 ... first photodiode

217 ... First optical receiver 221 ... Second differential line driver

223 ... 2nd relay 226 ... 2nd photoelectric diode

227. Second optical receiver

Half-duplex communication system according to the present invention to achieve the above object,

A first terminal having a first differential line driver transmitting a signal to another terminal and a first opto-coupler receiving a signal transmitted from another terminal;

A second terminal having a second optocoupler for receiving a signal transmitted from a first differential line driver of the first terminal and a second differential line driver for transmitting a signal to the first optocoupler of the first terminal; And

A transmission cable connecting the first terminal and the second terminal and having two lines; Its features are to include.

Here, the first terminal and the second terminal to which the transmission cable is connected, characterized in that the relay is further provided to control the connection of the signal transmission path, according to the direction of the signal transmitted through the transmission cable. .

According to the present invention, in the communication between the equipment, in the signal transmission by transmitting a signal using a differential line driver, and in receiving the signal by using a optocoupler to receive the signal, the signal ground between the equipment There is an advantage in that the signal can be transmitted / received using two lines of transmission cables without sharing the terminal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram schematically showing the configuration of a half-duplex communication system according to the present invention.

Referring to FIG. 2, the half-duplex communication system according to the present invention receives a first differential line driver 211 transmitting a signal to a second terminal 220 and a signal transmitted from the second terminal 220. A first terminal 210 having a first optocoupler 212; Signals are transmitted to a second optocoupler 222 that receives a signal transmitted from the first differential line driver 211 of the first terminal 210 and a first optocoupler 212 of the first terminal 210. A second terminal 220 having a second differential line driver 221 for transmitting; And a transmission cable 230 that connects the first terminal 210 and the second terminal 220 to each other.

Here, the first terminal 210 and the second terminal 220 to which the transmission cable 230 is connected, according to the direction of the signal transmitted through the transmission cable 230, controlling the connection of the signal transmission path First and second relays 213 and 223 are further provided, respectively. In addition, the resistor R1 of the first terminal 210 and the resistor R2 of the second terminal 220 are resistors for limiting a current flowing in the transmission path.

In addition, the first or second optocouplers 212 and 222 may include first or second photodiode diodes 216 and 226 that receive light and transmit light, and the first or second photocoupler diodes. And a first or second light receiver 217 or 227 for receiving a signal emitted from the 216 and 226.

Next, the operation of the half-duplex communication system having such a configuration will be described with reference to FIGS. 3 and 4. 3 is a diagram illustrating a control state when a signal is transmitted from a first terminal to a second terminal in the half-duplex communication system according to the present invention, and FIG. 4 is a case in which a signal is transmitted in the half-duplex communication system according to the present invention. The timing diagram of FIG.

First, referring to FIG. 3, a state in which a signal is transmitted from the first terminal 210 to the second terminal 220 will be described. The 'Tx enable' will be applied to the first differential line driver 211 of the first terminal 210. 'A control signal is applied to a state in which a signal can be transmitted, and a control signal of' Relay open 'is applied to the first relay 213 of the first terminal 210. Accordingly, the first optocoupler 212 of the first terminal 210 is in a state of 'Rx disable'.

When a signal is transmitted from the first terminal 210 to the second terminal 220, a control signal of 'relay close' is applied to the second relay 223 of the second terminal 220 to receive a signal. And a control signal of 'Tx disable' is applied to the second differential line driver 221 of the second terminal 220.

Accordingly, a signal transmitted through the first differential line driver 211 of the first terminal 210 is transmitted through the transmission cable 230 to the second optocoupler 222 of the second terminal 220. Can be received from. That is, as shown in Figure 4, by adjusting the timing of the control signal for the differential line driver 211 (221) and the relay 213 (223), by using the transmission cable 230 composed of two lines A signal can be transmitted / received between the first terminal 210 and the second terminal 220.

As described above, according to the half-duplex communication system according to the present invention, in performing communication between equipments, a signal is transmitted using a differential line driver to transmit a signal, and an optical coupler is used to receive a signal. By receiving the signal, there is an advantage that the signal can be transmitted / received by using two lines of transmission cables without sharing the signal ground terminal between devices.

Claims (2)

A first terminal having a first differential line driver transmitting a signal to another terminal and a first optocoupler receiving a signal transmitted from another terminal; A second terminal having a second optocoupler for receiving a signal transmitted from a first differential line driver of the first terminal and a second differential line driver for transmitting a signal to the first optocoupler of the first terminal; And A transmission cable connecting the first terminal and the second terminal and having two lines; Half-duplex communication system comprising a. The method of claim 1, The first terminal and the second terminal to which the transmission cable is connected, the half-duplex communication system, characterized in that each further provided with a relay for controlling the connection of the signal transmission path in accordance with the direction of the signal transmitted through the transmission cable.