Bus line data transceiver

Abstract

The invention relates to a bus data transmitter, a receiver and a transmission method, in particular to a bus data transmitter, wherein, the bus data transmitter is connected in parallel with a pair of cable bus with a special direct current power supply. The invention is characterized in that a transmitter switch S1 and a voltage source are connected in parallel with a bus; a capacitor C1 is connected in parallel with the switch S1 and the voltage source; a diode VD3 is unidirectionally conducted along the current direction of the special direct current power supply and connected in series with the voltage source; the voltage direction of the voltage source is opposite to that of the special direct current power supply; the voltage of the voltage source is less than that of the special direct current power supply; a diode VD2 is unidirectionally conducted along the current direction of the special direct current power supply and connected in series with a load, and then connected in parallel with the bus; an inductance L is connected in series between the bus and the direct current power supply. The invention has the advantages that data of ordinary control system (such as light control system) can be received and transmitted through the bus and the cost is low.

Description

technical field [0001] The invention relates to a data transmission device for control signals in industrial automatic control, in particular to a bus data transmitter, receiver and data transmission method. Background technique [0002] In the various existing industrial control systems, the use of fieldbus is the most effective means to realize the interconnection of field devices in order to maximize the use and dispatch of the intelligent processing functions of field devices. At present, the bus adopts multiple standards. For example, the RS-232-C bus standard is a serial physical interface standard formulated by EIA (Electronic Industry Association). For general duplex communication, one of its 25 signal lines can be used. Three lines are used to realize: one sending line, one receiving line and one grounding line. This standard can choose to set different data transmission rates, but since the driver only allows a capacitive load of 2500pF, the communication distance ...

AI Technical Summary

Problems solved by technology

At present, the bus adopts multiple standards. For example, the RS-232-C bus standard is a serial physical interface standard formulated by EIA (Electronic Industry Association). For general duplex communication, one of its 25 signal lines can be used. Three lines are used to realize: one sending line, one receiving line and one grounding line. This standard can choose to set different data transmission rates, but since the driver only allows a capacitive load of 2500pF, the communication distance is limited and can only transmit at most Another reason for the short transmission distance of tens of meters is that the bus is a single-ended signal transmission, which has problems such as common ground noise and inability to suppress common-mode interference, and is easily interfered by external signals. For some medium-distance transmission control systems, such as lighting Control system, this kind of bus is difficult to be well applied; at the same time, due to the use of unbalanced transmission mode, the signal is weak, and it needs to be amplified by operational amplifiers, so the cost is high. At the same time, many signal lines also lead to high costs

The RS-485 serial bus standard that is relatively commonly used today uses balanced transmission and differential reception, so it has the ability to suppress common mode interference, long transmission distance, high speed, and the maximum rate can reach 10Mbps when transmitting within 50Ft (feet). Megabytes / second), but when RS-485 adopts half-duplex mode, only one point is in the sending state at any time, so the sending circuit must be controlled by the enable signal, resulting in a complicated circuit structure, because two points The above are in the sending state at the same time, which will cause bus conflict and cause output short circuit

Neither of the above two bus standards can provide power for peripherals. The latest USB bus, a new interface standard jointly launched by seven world-renowned computer and communication companies, can provide power for peripherals. The communication rate can reach 12Mbps and it can also support multimedia. However, due to its pursuit of technical performance such as long-distance transmission and high-speed transmission, in the control field that does not need to meet these performance indicators, such as intelligent lighting control systems, the use of such buses will cause high costs, which is not conducive to intelligent lighting systems. Promoted application of

Images