CN219611758U

CN219611758U - USB-to-multipath Rs232 and Rs485 circuit capable of automatically resetting and selecting channels in switching mode

Info

Publication number: CN219611758U
Application number: CN202320414589.4U
Authority: CN
Inventors: 杜辉; 周彦中; 戴旭毅; 曾定坤
Original assignee: Weisheng Energy Technology Co ltd
Current assignee: Weisheng Energy Technology Co ltd
Priority date: 2023-03-08
Filing date: 2023-03-08
Publication date: 2023-08-29
Anticipated expiration: 2033-03-08

Abstract

The utility model discloses a channel switching automatic chip-selection-resetting USB-to-multipath Rs232 and Rs485 circuit, which comprises a four-to-one switch circuit, wherein the four-to-one switch circuit is respectively and electrically connected with a USB-to-TTL circuit, a chip selection pin reset circuit, a TTL-to-Rs 232 circuit and a TTL-to-Rs 485 circuit; the chip selection pin reset circuit comprises a collector electrode of a first triode and one end of a fifth resistor, wherein the collector electrode of the first triode is electrically connected with a chip selection pin of the one-out-of-four switching circuit; the emitter of the first triode is grounded; the base electrode of the first triode is electrically connected with one end of the eighth resistor, the first reset circuit and the second reset circuit; one end of the eighth resistor is electrically connected with the other end of the fifth resistor. The chip select pin reset circuit is added, so that crosstalk between analog channels is eliminated, and the stability of communication is improved.

Description

USB-to-multipath Rs232 and Rs485 circuit capable of automatically resetting and selecting channels in switching mode

Technical Field

The utility model relates to the field of machinery, in particular to a USB-to-multipath Rs232 and Rs485 circuit with a channel switching function and automatic reset function.

Background

In the field of industrial control field communication test, common communication protocols include Rs232 and Rs485, and because the current PC end mainly uses a USB interface, a module for converting USB to Rs232 and converting USB to Rs485 is often used for communication. In some fields, a plurality of Rs232 or Rs485 (for example, when a distributed DTU measurement and control unit terminal is produced, 2 paths of Rs232 and 2 paths of Rs485 are required to be respectively tested for communication with a master station), for example, each interface uses a communication module, and a USB port of a PC end is definitely required to be added; if the switching is to be pulled back and forth, the mechanical loss and the operation time are increased; if serial port expansion is utilized, an operator is required to select different serial port numbers during testing, and confusion is easy. The patent discloses a circuit for converting a single USB to RS485, RS422, RS232 and TTL levels, but the circuit does not have a chip select pin reset circuit, so that crosstalk influence is easy to occur.

Disclosure of Invention

In order to solve the technical problems, the utility model provides a USB-to-multipath Rs232 and Rs485 circuit with automatic reset chip selection during channel switching.

The aim of the utility model is achieved by the following technical scheme:

a USB-to-multipath Rs232, rs485 circuit with automatic reset chip selection during channel switching comprises a four-to-one switch circuit 1, wherein the four-to-one switch circuit 1 is electrically connected with a USB-to-TTL circuit 2, a chip selection pin reset circuit 3, a TTL-to-Rs 232 circuit 4 and a TTL-to-Rs 485 circuit 5 respectively; the chip selection pin reset circuit 3 comprises a collector electrode of a first triode Q1 and one end of a fifth resistor R5 which are electrically connected with a chip selection pin CS of the one-out-of-four switch circuit 1; the emitter of the first triode Q1 is grounded; the base electrode of the first triode Q1 is electrically connected with one end of an eighth resistor R8, a first reset circuit and a second reset circuit; the other end of one end of the eighth resistor R8 is electrically connected with the other end of the fifth resistor R5.

Further improved, the first reset circuit comprises one end of a tenth resistor R10 electrically connected with the base electrode of the first triode Q5, the other end of the tenth resistor R10 is electrically connected with one end of a twelfth capacitor (C12; the other end of the twelfth capacitor (C12 is electrically connected with the first switch K1, the positive electrode of the first diode D1 and one end of a fourth resistor R4; the negative electrode of the first diode D1 is electrically connected with one end of a second resistor R2, the other end of the second resistor R2 is grounded; the other end of the fourth resistor R4 is electrically connected with one end of the tenth capacitor C10, the negative electrode of the second diode D2 and the first address pin CHO of the switch circuit 1, the other end of the tenth capacitor C10 is grounded, and the positive electrode of the second diode D2 is electrically connected with one end of the third resistor R3.

Further improved, the second reset circuit comprises a fourteenth resistor R14 which is electrically connected with the base electrode of the first triode Q5, and the other end of the fourteenth resistor R14 is electrically connected with one end of a fifteenth capacitor C15; the other end of the fifteenth capacitor C15 is electrically connected with the second switch K2, the anode of the third diode D3 and one end of the sixteenth resistor R16; the negative electrode of the third diode D3 is electrically connected with one end of a seventeenth resistor R17, and the other end of the seventeenth resistor R17 is grounded; the other end of the sixteenth resistor R16 is electrically connected to the negative electrode of the fourth capacitor D4 and the second address pin CH1 of the one-out-of-four switching circuit 1, and the positive electrode of the fourth capacitor D4 is electrically connected to one end of the eighteenth resistor R18.

Further improved, the one-out-of-four switching circuit 1 is a 2 single-pole 4-throw analog switch chip of CH 444G.

Further improvement, the chip used by the USB-to-TTL circuit 2 is a CH340G chip; the chip used by the TTL-to-Rs 232 circuit 4 is an SP3232 chip; the chip used by the TTL-to-Rs 485 circuit 5 is an SP3485 chip.

Further improved, the one-out-of-four switch circuit (1) is electrically connected with an LED lamp through a dial switch.

The utility model has the beneficial effects that:

1. a USB interface and a serial number are used for realizing communication of multiple paths of Rs232 and Rs 485;

2. and a chip selection pin reset circuit is added to eliminate crosstalk between analog channels and improve the stability of communication.

3. Efficiency is improved, and module cost and operation actions are reduced.

Drawings

The utility model is further illustrated by the accompanying drawings, the content of which does not constitute any limitation of the utility model.

FIG. 1 is a block diagram of the overall circuit of the present utility model;

FIG. 2 is a schematic diagram of a chip select pin reset circuit;

FIG. 3 is a circuit diagram of a USB to TTL circuit;

FIG. 4 is a circuit diagram of a TTL to Rs232 circuit;

fig. 5 is a circuit diagram of a TTL to Rs485 circuit.

Detailed Description

The utility model will be further described in detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the utility model more apparent.

Example 1

The whole circuit block diagram of the utility model is shown in figure 1, and mainly comprises a USB-to-TTL circuit 2, a 4-to-one switch switching circuit 1, a chip selection pin reset circuit 3, a TTL-to-Rs 232 circuit 4 and a TTL-to-Rs 485 circuit 5.

The analog switch chip of the 4-choice switch switching circuit is a 2-single-pole 4-throw analog switch chip of Nanjing constant CH444G, and the chip has lower on-resistance and anti-interference capability than the traditional 74HC 4052. The analog switch chip needs to reset (pull up) the chip selection pins when switching channels, otherwise, crosstalk between adjacent channels still exists in a period of time after switching, and the circuit can realize the reset operation of the chip selection pins by adding an NPN triode by using a resistance-capacitance charge-discharge loop under the condition of not adding additional switching devices.

As shown in the chip select pin reset circuit shown in FIG. 2, the chip select pin CS is connected with the collector of Q1, and as Q1 is biased by R8, Q1 is in a conducting state, CS is 0 in default, and the analog switch is in a working state. When the switch K1 is switched from low level to high level, the capacitor C12 starts to charge, the triode base level voltage is suddenly changed from 0.7V to about-1.3V, the triode is cut off, CS is 1, the analog switch is in a non-working state, the channel switching is completed at the moment, after the C12 is fully charged, the Vb voltage is restored to 0.7V, Q1 is continuously conducted, CS is changed to 0 again, and the analog switch is in a working state again.

When the switch K1 is switched from high level to low level, the capacitor C12 starts to discharge, the triode base level voltage is suddenly changed from 0.7V to-5V, the triode is cut off, CS is 1, the analog switch is in a non-working state, the channel switching is completed at the moment, when the C12 is discharged, the voltage Vb is restored to 0.7V, the Q1 is continuously conducted, CS is changed to 0 again, and the analog switch is in a working state again.

The high-low level switching is utilized to charge and discharge the capacitor, so that the pulse generated by the cut-off of the triode realizes the chip selection reset of the switch chip, thereby eliminating the crosstalk generated during switching, and the two switches are connected in parallel to realize the switching of four channels.

As shown in fig. 3-5, the circuit for converting usb to TTL, converting TTL to Rs232, and converting TTL to Rs485 has already a mature circuit module in reality, and only a circuit is attached here, which will not be described in detail

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present utility model and not for limiting the scope of the present utility model, and although the present utility model has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present utility model without departing from the spirit and scope of the technical solution of the present utility model.

Claims

1. The USB-to-multipath Rs232 and Rs485 circuit capable of automatically resetting chip selection during channel switching is characterized by comprising a four-to-one switching circuit (1), wherein the four-to-one switching circuit (1) is electrically connected with a USB-to-TTL circuit (2), a chip selection pin reset circuit (3), a TTL-to-Rs 232 circuit (4) and a TTL-to-Rs 485 circuit (5) respectively; the chip selection pin reset circuit (3) comprises a collector electrode of a first triode (Q1) and one end of a fifth resistor (R5), wherein the collector electrode of the first triode (Q1) is electrically connected with a chip selection pin (CS) of the one-out-of-four switch circuit (1); the emitter of the first triode (Q1) is grounded; the base electrode of the first triode (Q1) is electrically connected with one end of an eighth resistor (R8), the first reset circuit and the second reset circuit; one end and the other end of the eighth resistor (R8) are electrically connected with the other end of the fifth resistor (R5).

2. The channel-switching, auto-resettable USB to multi-way Rs232, rs485 circuit of claim 1, wherein the first reset circuit comprises a tenth resistor (R10) having one end electrically connected to the base of the first transistor (Q1), the other end of the tenth resistor (R10) being electrically connected to one end of a twelfth capacitor (C12); the other end of the twelfth capacitor (C12) is electrically connected with one end of the first switch (K1), the anode of the first diode (D1) and the fourth resistor (R4); the negative electrode of the first diode (D1) is electrically connected with one end of a second resistor (R2), and the other end of the second resistor (R2) is grounded; the other end of the fourth resistor (R4) is electrically connected with one end of the tenth capacitor (C10), the negative electrode of the second diode (D2) and the first address pin (CHO) of the one-out-of-four switching circuit (1); the other end of the tenth capacitor (C10) is grounded, and the anode of the second diode (D2) is electrically connected with one end of the third resistor (R3).

3. The channel-switching, auto-resettable USB to multi-way Rs232, rs485 circuit of claim 1, wherein the second reset circuit comprises a fourteenth resistor (R14) having one end electrically connected to the base of the first transistor (Q1), the other end of the fourteenth resistor (R14) being electrically connected to one end of a fifteenth capacitor (C15); the other end of the fifteenth capacitor (C15) is electrically connected with the second switch (K2), the anode of the third diode (D3) and one end of the sixteenth resistor (R16); the negative electrode of the third diode (D3) is electrically connected with one end of a seventeenth resistor (R17), and the other end of the seventeenth resistor (R17) is grounded; the other end of the sixteenth resistor (R16) is electrically connected with the negative electrode of the fourth capacitor (D4) and the second address pin (CH 1) of the one-out-of-four switching circuit (1), and the positive electrode of the fourth capacitor (D4) is electrically connected with one end of the eighteenth resistor (R18).

4. The channel switching automatic chip-resetting USB-to-multipath Rs232, rs485 circuit as claimed in claim 1, wherein the chip used in the one-out-of-four switching circuit (1) is a 2 single-pole 4-throw analog switch chip of CH 444G.

5. The circuit of claim 1, wherein the chip-switched, automatically resettable, USB-to-multi-path Rs232, rs485 circuit is characterized in that the chip used in the circuit (2) is a CH340G chip; the chip used by the TTL-to-Rs 232 circuit (4) is an SP3232 chip; the chip used by the TTL-to-Rs 485 circuit (5) is an SP3485 chip.

6. The channel switching automatic chip-selection USB-to-multichannel Rs232 and Rs485 circuit as claimed in claim 1, wherein the one-to-four switching circuit (1) is electrically connected with an LED lamp through a dial switch.