CN203149566U

CN203149566U - RS232 interface circuit

Info

Publication number: CN203149566U
Application number: CN 201320162123
Authority: CN
Inventors: 张洁; 李国军; 张毅宁; 崔群
Original assignee: Anshan Normal University
Current assignee: Anshan Normal University
Priority date: 2013-04-02
Filing date: 2013-04-02
Publication date: 2013-08-21
Anticipated expiration: 2023-04-02

Abstract

The utility model relates to the field of communication interface circuits, in particular to an RS232 interface circuit. The RS232 interface circuit is characterized in that a first conditioning circuit is arranged between an MAX232 integrated circuit and a nine-core RS232 connector to form a first electricity stealing access, the input end of the first conditioning circuit is connected with a V+ pin of the MAX232 integrated circuit, the output end of the first conditioning circuit is connected with a fourth base pin of the nine-core RS232 connector, and the grounding end of the first conditioning circuit is connected with a fifth base pin of the nine-core RS232 connector and is connected to the ground. Another mode is that under the condition that the first conditioning circuit is arranged, a second conditioning circuit is arranged between the MAX232 integrated circuit and the nine-core RS232 connector to form a second electricity stealing access. Compared with the prior art, the RS232 interface circuit has the advantages that an RS232 interface is guaranteed to be always reliably in communication with an RS485 interface through a passive RS232/RS485 converter under any condition.

Description

A kind of RS232 interface circuit

Technical field

The utility model relates to communication interface circuit field between the electronic equipment, particularly a kind of RS232 interface circuit.

Background technology

Industrial electronic instrument product majority is furnished with RS-232 or RS-485 communication port at present, simultaneously can be by the RS232/RS485 converter realization flexible conversion that buys in market between RS-232 and the RS-485 communication port, so the electronic device product only need be furnished with wherein that a kind of communication port gets final product as required.

RS-232 interface is the interface that industrial control computer generally is equipped with, its RS232 port pinout is defined as follows that (the RS232 port has two kinds of forms of 9 and 25 cores shown in the table 1, wherein 9 cores are the most commonly used), provide passive and active two kinds of RS232/RS485 converters on the market, to realize the mutual conversion between RS232 and two kinds of communication ports of RS485.

Passive RS232/RS485 converter since when using line simple and cheaply generally receive an acclaim, the required power supply of passive RS232/RS485 converter generally obtains by RS232 port " TXD ", " DTR ", " DSR ", " RTS ", the stealing of " CTS " pin, for the standard RS232 port of microcomputer and equipment thereof configuration mainly by " TXD ", " DTR ", the stealing of " RTS " pin.The RS232 interface configuration of computing machine is carried out in strict accordance with RS232 communication protocol and electrical standard, and the RS232 interface of instrument configuration only needs simply with two communication logic signals " TXD " usually, after " RXD " carries out level conversion (for example adopting the MAX232 of MAXIM company) according to the RS232 electrical standard, being connected to the RS232 connector gets final product, the RS232 interface pin connects as shown in Figure 1, the stealing of the passive RS232/RS485 converter of this situation is that the 3rd pin " TXD " by 9 core RS232 ports carries out, when usually occurring the phenomenon that can't carry out when carrying out communication with the equipment of being furnished with the RS485 port (for example S7-200PLC), this mainly be the electric weight that obtains not enough due to.

Table 1

Summary of the invention

The purpose of this utility model provides a kind of RS232 interface circuit, this interface circuit is on the basis of normal " TXD ", " RXD " communication line, for passive RS232/RS485 converter increases the stealing path, under any circumstance all can communicate by passive RS232/RS485 converter and RS485 interface reliably to guarantee the RS232 interface.

For achieving the above object, the utility model adopts following technical scheme to realize:

A kind of RS232 interface circuit, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit one and constitute stealing path one, the input end of modulate circuit one links to each other with the V+ pin of MAX232 integrated circuit, the output terminal of modulate circuit one links to each other with the 4th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit one links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground.

Another kind of RS232 interface circuit, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit two and constitute stealing path two, the input end of modulate circuit two links to each other with the T2out pin of MAX232 integrated circuit, the output terminal of modulate circuit two links to each other with the 7th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit two links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground.

Also having a kind of form is under the situation that is provided with modulate circuit one, is provided with modulate circuit two between MAX232 integrated circuit and 9 core RS232 connectors, forms two stealing paths simultaneously.

In the structure of described modulate circuit one, comprise resistance one R1, resistance two R2, diode one D1 and diode two D2, the just very input end of diode one D1, the negative pole of diode one D1 links to each other with the end of resistance one R1, the other end of resistance one R1 links to each other with the end of resistance two R2, the negative pole of diode two D2 respectively, the other end of resistance two R2 is output terminal, the just very earth terminal of diode two D2.

In described modulate circuit two structures, comprise resistance three R3, resistance four R4, diode three D3 and diode four D4, the just very input end of diode three D3, the negative pole of diode three D3 links to each other with the end of resistance three R3, the other end of resistance three R3 links to each other with the end of resistance four R4, the negative pole of diode four D4 respectively, the other end of resistance four R4 is output terminal, the just very earth terminal of diode four D4.

Compared with prior art, the beneficial effects of the utility model are: having increased modulate circuit is that passive RS232/RS485 converter increases the stealing path, guaranteed that the RS232 interface under any circumstance all can communicate by passive RS232/RS485 converter and RS485 interface reliably, and can be according to the equipment concrete condition increase and decrease stealing path of communication with it, use is simple and direct and safe and reliable.

Description of drawings

Fig. 1 is the general interface circuit figure of RS232 that constitutes with MXA232;

Fig. 2 is the structural representation of the utility model embodiment one;

Fig. 3 is the structural representation of embodiment two of the present utility model;

Fig. 4 is the structural representation of embodiment three of the present utility model;

Fig. 5 is the internal circuit diagram of the utility model modulate circuit one;

Fig. 6 is the internal circuit diagram of the utility model modulate circuit two.

Embodiment

Below in conjunction with accompanying drawing embodiment of the present utility model is described further:

Embodiment 1

See Fig. 2, it is a kind of RS232 interface circuit, be between MAX232 integrated circuit and 9 core RS232 connectors, to be provided with modulate circuit one to constitute stealing path one, the input end of modulate circuit one links to each other with the V+ pin of MAX232 integrated circuit, the output terminal of modulate circuit one links to each other with the 4th pin of 9 core RS232 connectors, the earth terminal of modulate circuit one links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground, realizes the high level pumping source stealing from MAX232 integrated circuit V+ pin.

Embodiment 2

See Fig. 3, it is another kind of RS232 interface circuit, be between MAX232 integrated circuit and 9 core RS232 connectors, to be provided with modulate circuit two to constitute stealing path two, the input end of modulate circuit two links to each other with the T2out pin of MAX232 integrated circuit, the output terminal of modulate circuit two links to each other with the 7th pin of 9 core RS232 connectors, the earth terminal of modulate circuit two links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground, the high level signal of MAX232 integrated circuit the 7th pin (T2out) output RS232 level standard is for the passive RS232/RS485 converter in downstream provides another stealing path.

Embodiment 3

See Fig. 4, it is the third RS232 interface circuit, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit one and constitute stealing path one, the input end of modulate circuit one links to each other with the V+ pin of MAX232 integrated circuit, the output terminal of modulate circuit one links to each other with the 4th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit one links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground; Between MAX232 integrated circuit and 9 core RS232 connectors, be provided with simultaneously modulate circuit two and constitute stealing path two, the input end of modulate circuit two links to each other with the T2out pin of MAX232 integrated circuit, the output terminal of modulate circuit two links to each other with the 7th pin of 9 core RS232 connectors, the earth terminal of modulate circuit two links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground, and two stealing paths are provided simultaneously.

See Fig. 5, in above-described embodiment, in the structure of modulate circuit one, comprise resistance one R1, resistance two R2, diode one D1 and diode two D2, the just very input end of diode one D1, the negative pole of diode one D1 links to each other with the end of resistance one R1, the other end of resistance one R1 links to each other with the end of resistance two R2, the negative pole of diode two D2 respectively, the other end of resistance two R2 is output terminal, the just very earth terminal of diode two D2, and diode two D2 play clamping action.Diode one D1 plays and anti-pours in down a chimney effect in the circuit, and resistance one R1, resistance two R2 play the protection buffer action.

See Fig. 6; in above-described embodiment; in modulate circuit two structures; comprise resistance three R3, resistance four R4, diode three D3 and diode four D4; the just very input end of diode three D3; the negative pole of diode three D3 links to each other with the end of resistance three R3; the other end of resistance three R3 links to each other with the end of resistance four R4, the negative pole of diode four D4 respectively; the other end of resistance four R4 is output terminal; the just very earth terminal of diode four D4; diode four D4 play clamping action, and diode three D3 play and anti-pour in down a chimney effect in the circuit, and resistance three R3, resistance four R4 play the protection buffer action.

The utility model still can reliably guarantee proper communication during with passive RS232/RS485 converter between the equipment that has also guaranteed to be furnished with the equipment of RS232 communication port and to be furnished with the RS485 communication port when guaranteeing to be furnished with RS232 communication port communication between devices.

Claims

1. RS232 interface circuit, it is characterized in that, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit one and constitute stealing path one, the input end of modulate circuit one links to each other with the V+ pin of MAX232 integrated circuit, the output terminal of modulate circuit one links to each other with the 4th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit one links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground.

2. RS232 interface circuit, it is characterized in that, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit two and constitute stealing path two, the input end of modulate circuit two links to each other with the T2out pin of MAX232 integrated circuit, the output terminal of modulate circuit two links to each other with the 7th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit two links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground.

3. a kind of RS232 interface circuit according to claim 1, it is characterized in that, between MAX232 integrated circuit and 9 core RS232 connectors, be provided with modulate circuit two and constitute stealing path two, the input end of modulate circuit two links to each other with the T2out pin of MAX232 integrated circuit, the output terminal of modulate circuit two links to each other with the 7th pin of 9 core RS232 connectors, and the earth terminal of modulate circuit two links to each other with the 5th pin of 9 core RS232 connectors and connects signal ground.

4. according to claim 1 or 3 described a kind of RS232 interface circuits, it is characterized in that, in the structure of described modulate circuit one, comprise resistance one R1, resistance two R2, diode one D1 and diode two D2, the just very input end of diode one D1, the negative pole of diode one D1 links to each other with the end of resistance one R1, and the other end of resistance one R1 links to each other with the end of resistance two R2, the negative pole of diode two D2 respectively, the other end of resistance two R2 is output terminal, the just very earth terminal of diode two D2.

5. according to claim 2 or 3 described a kind of RS232 interface circuits, it is characterized in that, in described modulate circuit two structures, comprise resistance three R3, resistance four R4, diode three D3 and diode four D4, the just very input end of diode three D3, the negative pole of diode three D3 links to each other with the end of resistance three R3, and the other end of resistance three R3 links to each other with the end of resistance four R4, the negative pole of diode four D4 respectively, the other end of resistance four R4 is output terminal, the just very earth terminal of diode four D4.