CN103034604A

CN103034604A - Conversion equipment of universal serial bus (USB) and various serial ports and realization method thereof

Info

Publication number: CN103034604A
Application number: CN2011102928533A
Authority: CN
Inventors: 朱正兴; 王娟
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-06
Filing date: 2011-10-06
Publication date: 2013-04-10

Abstract

The invention relates to conversion equipment of a universal serial bus (USB) and various serial ports and realization method of conversion of the USB and the various serial ports. The conversion equipment comprises a USB transceiver, a logic module, a receiving and transmitting automatic conversion module, an RS232 transceiver, two RS485 transceivers and corresponding port elements, wherein the two RS485 transceivers are capable of achieving the functions of an RS422 transceiver. By means of the logic module and the receiving and transmitting automatic conversion module, under the condition of no additional operation, the conversion equipment is simultaneously provided with the functions of the conversion from a USB to an RS232, the conversion form the USB to an RS485 and the conversion from the USB to an RS422.

Description

The conversion equipment of USB and multiple serial ports and its implementation

Technical field

The invention belongs to the serial communication field, relate to computing machine USB communication commonly used and RS232, RS485, the RS422 communication commonly used of electric information product.

Background technology

Serial communication refers to the in order communication modes of bit by bit transfer of data message.By the direction of transfer of information, can be divided into three kinds of single worker, half-duplex and full duplexs; And can according to whether the needs synchronous clock, be divided into asynchronous serial communication and synchronous serial communication.

USB is Universal Serial BUS(USB (universal serial bus)) abbreviation, be an external bus standard, be used for being connected and communication of proper calculation machine and external unit.USB interface uses semiduplex differential signal to carry out communication, and the plug and play of support equipment and warm connection function have experienced the upgrading of a plurality of versions, is one of communication interface the most frequently used on the present computing machine.

RS232, RS485, RS422 are asynchronous serial communication interfaces commonly used in the electric information product, wherein RS232 and RS422 can realize the communication mode of full duplex, the electric property of RS485 and RS422 is just the same, the key distinction is that RS422 has two pairs of differential signal lines, realize simultaneously receiving and sending data, and RS485 only has a pair of differential signal line, and time-sharing multiplex realizes receiving and sending data.The minimum connection that realizes the RS232 communication comprises the RXD(receive data), TXD(sends data), the SGND(signal ground).

Have in the market similar products, but do not possess simultaneously the USB RS 232, USB turns RS485, USB turns RS422 function, perhaps need the switching by the manual mode practical function of selecting, this brings no small trouble to the user.

Summary of the invention

The present invention is by increasing the method for logic module (Fig. 1-2) and transmitting-receiving automatic switching module (Fig. 1-3), and the realization conversion equipment is in the situation that need operation bidirectional, possesses simultaneously the USB RS 232, USB turns the function that RS485, USB turn RS422.

Logic module (Fig. 1-2) can realize the logical and function to the reception pin (RO) of the reception pin (RxOUT) of RS232 transceiver (Fig. 1-4), two RS485 transceivers (Fig. 1-5 and Fig. 1-6) at least.

Transmitting-receiving automatic switching module (Fig. 1-3) and RS485 transceiver (Fig. 1-5) are realized RS485 serial communication transmitting-receiving automatic switching function, with reference to realizing circuit as shown in Figure 3 and Figure 4.

Description of drawings

Fig. 1: theory diagram of the present invention.

Fig. 2: a kind of circuit diagram that possesses logic module (Fig. 1-2) function.

Fig. 3: a kind of RS485 serial communication circuit figure with transmitting-receiving automatic switchover.

Fig. 4: another has the RS485 serial communication circuit figure that transmitting-receiving is automaticallyed switch.

Fig. 5: a kind of circuit diagram of USB transceiver.

Fig. 6: a kind of circuit diagram of RS232 transceiver.

Fig. 7: a kind of circuit diagram of RS422 transceiver.

Embodiment

The present invention at first will receive and dispatch automatic switching module (Fig. 1-3) and RS485 transceiver (Fig. 1-5) is combined into the RS485 transmission circuit with transmitting-receiving automatic switching function, Fig. 3 and Fig. 4 are reference circuits, wherein RS485_RXD receives pin, and RS485_TXD sends pin.The RS485 transmission circuit that transmitting-receiving is automaticallyed switch also can be realized with other method.

The USB transceiver can use CP2102, and as shown in Figure 5, wherein RXD receives pin, and TXD sends pin, also can use the USB transceivers such as PL2303, FT2232, CP2104; The RS232 transceiver can use SP3232, and as shown in Figure 6, wherein RS232_RXD receives pin, and RS232_TXD sends pin, also can use the RS232 transceivers such as MAX232; For multiplexing with the RS485 transceiver, the RS422 transceiver uses two RS485 transceivers, a responsible transmitting data, another is responsible for receive data, and as shown in Figure 7, wherein RS422_RXD receives pin, RS422_TXD sends pin, and RS422_TXD and RS485_TXD are same pin.

This conversion equipment is after energising, when not carrying out data transmission, the transmission pin (TXD) of USB transceiver (Fig. 1-1), the reception pin (RS232_RXD) of RS232 transceiver (Fig. 1-4), the reception pin (RS485_RXD and RS422_RXD) of two RS485 transceivers (Fig. 1-5 and Fig. 1-6) all is in logic level 1(high level) state, the reception pin of RS232 transceiver and two RS485 transceivers carries out logic and operation by logic module (Fig. 1-2), operation result links to each other with the reception pin (RXD) of USB transceiver (Fig. 1-1), Fig. 2 is a kind of circuit of realizing logic and operation, also can realize logic and operation by other forms of circuit.

When carrying out USB to the data transmission of RS232, RS485, RS422, the transmission pin of USB transceiver sends by the mode of asynchronous serial communication, behind driving circuit, link to each other with the transmission pin (RS232_TXD) of RS232 transceiver and the transmission pin (RS485_TXD) of RS485 transceiver (also being the transmission pin of RS422 transceiver), convert respectively the output of RS232 level and RS485 level to; When carrying out RS232, RS485, RS422 to the data transmission of USB, the reception pin (RxOUT) of RS232 transceiver, the reception pin (RS485_RXD) of RS485 transceiver, reception pin (RS422_RXD) timesharing of RS422 transceiver is single effectively, after logic module, link to each other with the reception pin (RXD) of USB transceiver.

Claims

1. the conversion equipment of a USB and multiple serial ports is characterized in that: in the situation that do not need operation bidirectional, possess simultaneously the USB RS 232, USB turns the function that RS485, USB turn RS422.

2. conversion equipment according to claim 1 is characterized in that: realize by the method that increases logic module (2) and transmitting-receiving automatic switching module (3).

3. conversion equipment according to claim 1 should comprise USB transceiver (1), logic module (2), transmitting-receiving automatic switching module (3), RS232 transceiver (4), two RS485 transceivers (5 and 6) and corresponding interface device.

4. two RS485 transceivers according to claim 3 (5 and 6) is characterized in that: a RS485 transceiver (5) is realized transmission-receiving function, and another RS485 transceiver (6) is only realized receiving function; The receiving function of the sending function of RS485 transceiver (5) and RS485 transceiver (6) is combined into the RS422 serial communication of full duplex.

5. transmitting-receiving automatic switching module according to claim 3 (3) and RS485 transceiver (5), it is characterized in that: the RS485 serial communication can realize receiving and dispatching automatic switching function.

6. RS232 transceiver according to claim 3 (4) should can be realized the data transmit-receive of RS232 serial communication at least.

7. conversion equipment according to claim 3, it is characterized in that: after energising, when not carrying out data transmission, the reception pin (RO) of the transmission pin (TXD) of USB transceiver (1), the reception pin (RxOUT) of RS232 transceiver (4), two RS485 transceivers (5 and 6) all is in logic level 1(high level) state.

8. logic module according to claim 3 (2) should can realize the logical and function of the reception pin (RO) of reception pin (RxOUT), two RS485 transceivers (5 and 6) to RS232 transceiver (4) at least.