Bus line data transceiver

Abstract

The present invention is a bus data transmitter, which relates to a bus data transmitter, a receiver and a data transmission method. The bus data transmitter is connected in parallel to a pair of cable buses with a dedicated DC power supply, and is characterized in that it includes a transmitter switch S1 and a voltage source that are respectively connected in parallel on the bus, and are connected in series with the switch S1 and then connected to the bus in parallel. The capacitor C1 above also includes a diode VD3 that conducts unidirectionally along the current direction of the dedicated DC power supply. The diode VD3 is connected in series with the voltage source and then connected in parallel with the switch S1. The voltage direction of the voltage source is opposite to the dedicated DC power supply voltage direction, and The other diode VD2, which is less than the dedicated DC power supply voltage and conducts unidirectionally along the dedicated DC power supply current direction, is connected in series with the load, and then connected to the bus in parallel; an inductor L is connected in series between the bus and the DC power supply. The invention can realize the data sending and receiving requirements of common control systems such as lighting control systems on the bus, and at the same time, 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

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