CN210402331U

CN210402331U - RS232 and RS485 communication interface converter

Info

Publication number: CN210402331U
Application number: CN201921972413.0U
Authority: CN
Inventors: 谢世华; 罗汉生; 刘珂
Original assignee: Shenzhen Stone Electric Co ltd
Current assignee: Shenzhen Stone Electric Co ltd
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2020-04-24
Anticipated expiration: 2029-11-12

Abstract

The utility model relates to the technical field of communication interfaces, and discloses a RS232 and RS485 communication interface converter, wherein the input/output end of the RS232 communication interface is connected with the input/output end of the RS485 communication interface; the signal input end of the low-power consumption microprocessor is coupled with the signal output end of the DC-DC converter; the signal input end of the low-power consumption microprocessor is coupled with the signal output end of the RS232 communication interface and is used for receiving an enabling signal output by the RS232 communication interface; a signal receiving end of the RS485 communication interface is connected with a signal output end of the low-power-consumption microprocessor; and detecting the change of the enabling signal through a low-power-consumption microprocessor to determine the transmission or the reception of data between the RS232 communication interface and the RS485 communication interface. This scheme possesses the higher converter that just need not outside power supply intelligence and receive and dispatch of commonality.

Description

RS232 and RS485 communication interface converter

Technical Field

The utility model relates to a communication interface technical field, more specifically say, relate to a RS232 and RS485 communication interface converter.

Background

With the wide industrial application of computers, the control area network is also deeply applied to various industries. In many existing control systems, it is increasingly difficult to meet the requirement of controlling the equipment by using a single-machine control method, because the equipment to be controlled is only one basic unit of the whole system, which requires to input some necessary information externally, and also needs to output its own operating parameters and states externally. All of these, it is necessary to use control network technology to organically connect a plurality of devices together to ensure the safe and reliable operation of the whole system.

At present, RS-485 is most commonly used in field buses applied in China. When a user wants to connect a standard-based RS-232 interface device, such as a PC, to a communication network formed by RS-485, level conversion between RS-232 and RS-485 is required, conventionally, a communication adapter card is extended in the device, the level conversion is realized by the communication adapter card, and an internal host reads or writes data through a parallel bus.

The design method has the defects that the application range of the adapter card is limited because the adapter card is based on a bus standard extension rather than an RS-232 level standard, the adapter card is suitable for a bus (such as an ISA adapter card which cannot be inserted into an STD bus or a bus customized by a user), and the universality is poor.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model lies in, the above-mentioned adapter card to prior art is based on a bus standard extension, and not based on RS-232 level standard, and its range of application receives the defect of restriction, provides a commonality higher and need not the intelligent receiving and dispatching RS232 and RS485 communication interface converter of external power supply.

The utility model provides a technical scheme that its technical problem adopted is: an RS232 and RS485 communication interface converter is constructed, and comprises a DC-DC converter, an RS232 communication interface, an RS485 communication interface and a low-power-consumption microprocessor;

the signal input end of the DC-DC converter is connected with the signal output end of the RS232 communication interface and is used for acquiring a level signal output by the RS232 communication interface;

the input/output end of the RS232 communication interface is mutually connected with the input/output end of the RS485 communication interface and is used for data intercommunication;

the signal input end of the low-power consumption microprocessor is coupled with the signal output end of the DC-DC converter;

the signal input end of the low-power-consumption microprocessor is coupled with the signal output end of the RS232 communication interface and is used for receiving an enabling signal output by the RS232 communication interface;

a signal receiving end of the RS485 communication interface is connected with a signal output end of the low-power-consumption microprocessor;

and detecting the change of the enabling signal through the low-power microprocessor to determine the transmission or the reception of data between the RS232 communication interface and the RS485 communication interface.

In some embodiments, the DC-DC converter includes a first controller, a first resistor, a second resistor, and a first transistor,

the signal input end of the first controller is connected with the output end of the RS232 communication interface;

one end of the first resistor is connected with a level end, and the other end of the first resistor is coupled to an emitting electrode of the first triode;

a collector of the first triode is connected with a voltage feedback end of the first controller and one end of the second resistor;

and the other end of the second resistor is connected with the output end of the RS232 communication interface.

In some embodiments, the DC-DC converter further comprises a first inductor, a first diode, a second diode, a third diode, and a fourth diode,

one end of the first inductor is connected with the anode of the first diode, and the other end of the first inductor is coupled to the power input end of the first controller;

the cathode of the first diode is connected with one end of the first resistor;

the cathode of the second diode is connected with the output end of the RS232 communication interface, and the anode of the second diode is coupled with the voltage detection end of the first controller;

the cathode of the third diode is connected with the output end of the RS232 communication interface, and the anode of the third diode is coupled with the reference voltage end of the first controller;

the cathode of the fourth diode is connected with the output end of the RS232 communication interface, and the anode of the fourth diode is coupled to one end of the second resistor.

In some embodiments, the RS485 communication interface converter comprises a second controller, an input end of the second controller is connected with an output end of the RS232 communication interface,

an output terminal of the second controller is coupled to an input terminal of the RS232 communication interface.

In some embodiments, the RS485 communication interface converter further comprises a third controller, an input of the third controller being coupled to an output of the second controller;

the input end of the third controller is coupled to the output end of the low-power microprocessor.

In some embodiments, the RS485 communication interface converter further includes a third resistor, one end of the third resistor is connected to the output end of the third controller, and the other end of the third resistor is connected to a connection terminal.

The RS232 and RS485 communication interface converter of the present invention comprises a DC-DC converter, an RS232 communication interface, an RS485 communication interface and a low power consumption microprocessor; the signal input end of the DC-DC converter is connected with the signal output end of the RS232 communication interface, and the input/output end of the RS232 communication interface is mutually connected with the input/output end of the RS485 communication interface and used for data intercommunication; the signal input end of the low-power consumption microprocessor is coupled with the signal output end of the DC-DC converter; the signal input end of the low-power consumption microprocessor is coupled with the signal output end of the RS232 communication interface and is used for receiving an enabling signal output by the RS232 communication interface; a signal receiving end of the RS485 communication interface is connected with a signal output end of the low-power-consumption microprocessor; and detecting the change of the enabling signal through the low-power-consumption microprocessor to determine the transmission or the reception of data between the RS232 communication interface and the RS485 communication interface. Compared with the prior art, the change of the enable signal is detected by the low-power-consumption microprocessor to determine the sending or receiving of data between the RS232 communication interface and the RS485 communication interface, the defect of poor universality of the adapter card is effectively overcome, a built-in plug-in card is not needed, the communication changing method is simple and convenient, and the use cost is further reduced.

Drawings

The invention will be further explained with reference to the drawings and examples, wherein:

fig. 1 is a schematic diagram of an internal circuit structure of an embodiment of the RS232 and RS485 communication interface converter provided in the present invention;

fig. 2 is a partial circuit diagram of an embodiment of a DC-DC converter;

fig. 3 is a circuit diagram of the present invention for switching between RS232 and RS485 communication interface.

Detailed Description

In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of an internal circuit structure of an embodiment of the RS232 and RS485 communication interface converter provided in the present invention; fig. 2 is a partial circuit diagram of an embodiment of a DC-DC converter; fig. 3 is a circuit diagram of the present invention for switching between RS232 and RS485 communication interface. As shown in fig. 1 to fig. 3, in the first embodiment of the RS232 and RS485 communication interface converter of the present invention, the RS232 and RS485 communication interface converter is used as an independent level shifter, which relates to the on-line power taking, intelligent switching of sending and receiving states, setting of communication method, and the conversion between RS232 level and RS485 level. Specifically, the system mainly includes a DC-DC converter 100, an RS232 communication interface 200, a low power consumption microprocessor 300 (corresponding to the processor U3), and an RS485 communication interface 400.

Specifically, the operating principle of the DC-DC converter 100 is: the voltage conversion function is completed by using elements such as an inductor, a capacitor and the like as energy storage elements, namely, the input direct current is converted into alternating current, and then the alternating current is converted into direct current for output after the voltage is changed by a transformer, or the alternating current is converted into high-voltage direct current for output.

The DC-DC converter 100 operates a high-frequency switch by a controllable switch (such as a MOSFET) to store input electric energy in a capacitor (inductor), and when the switch is turned off, the electric energy is released to a load to supply energy.

Specifically, a signal input end of the DC-DC converter 100 is connected to a signal output end of the RS232 communication interface 200, and is configured to obtain a level signal output by the RS232 communication interface, where the level signal is 12V voltage, and an internal boost operating voltage source is provided by the level signal.

The RS232 communication interface is provided with three signal sending ends, specifically: the output level signal of each line of the RS-TXD (corresponding to the sending data terminal), the RS-RTS (corresponding to the requesting sending terminal) and the RS-DTR (corresponding to the data terminal ready) is 12V voltage, and the time when the RS-TXD (corresponding to the sending data terminal) is at the negative level (at the time of stopping sending, or when the sending number is "1") is longer, so that the DC-DC converter 100 adopts the negative power input to increase the input power to the maximum extent and boost the input power to the required working power.

For example, since the communication is in an intermittent operation mode, the capacitor at the input power end and the RS-TXD (at a negative level) can supplement a certain power, and the voltage of 12V is converted into a voltage of +3V or +5V through the conversion of the DC-DC converter 100.

The input/output end of the RS232 communication interface 200 is connected to the input/output end of the RS485 communication interface 400 for data communication.

Specifically, the RS232 communication interface 200 adopts level mode transmission, is suitable for point-to-point communication, does not need special transceiving enabling control, and is different from the RS485 communication interface 400 in that differential level mode transmission is adopted, and multiple nodes are allowed to be hooked on one communication bus, and each node is inevitably required to be capable of independently controlling the bus driver to be turned off or turned on, so as to ensure that normal communication of other nodes is not affected.

The low power consumption microprocessor 300 (corresponding to the processor U3) is a core element of the converter, which performs automatic control of setting achievable parameters and transmission enabling through I/O lines, and controls conversion between RS232 level and TTL level, and conversion between RS485 level and TTL level.

The UART controller is provided with a multiplexing output pin (corresponding to GP0 and GP1 ends), an RS-TXD input (corresponding to GP2 end) and an 11-bit serial data format (corresponding to GP3 end), wherein the multiplexing output pin (corresponding to GP0 and GP1 ends) is used for controlling the receiving enabling of a third controller U4, and the RS-TXD input (corresponding to GP2 end) is used for detecting when the UART sends and stops data.

The signal input terminal of the low power consumption microprocessor 300 (corresponding to the processor U3) is coupled to the signal output terminal of the DC-DC converter 100, and receives the +3V or +5V voltage outputted from the DC-DC converter 100 to drive the low power consumption microprocessor 300 (corresponding to the processor U3) to operate.

A signal input terminal of the low power consumption microprocessor 300 (corresponding to the processor U3) is coupled to the signal output terminal of the RS232 communication interface 100, and is configured to receive an enable signal output by the RS232 communication interface 100, and further control data interaction between an input/output terminal of the RS232 communication interface 200 and an input/output terminal of the RS485 communication interface 400 according to parameters set therein.

The signal receiving end of the RS485 communication interface 400 is connected to the signal output end of the low power consumption microprocessor 300 (corresponding to the processor U3).

Further, the change of the enable signal (i.e., the change of the high level or the low level) is detected by the low power consumption microprocessor 300 (corresponding to the processor U3) to determine the transmission or reception of data between the RS232 communication interface 200 and the RS485 communication interface 400.

For example, the low power microprocessor 300 (corresponding to the processor U3) turns on the transmit enable after detecting the start of communication of UART (universal asynchronous receiver transmitter) and allows serial data to be transmitted to the RS485 communication interface 400 communication network. The low power consumption microprocessor 300 (corresponding to the processor U3) starts to detect whether the next start bit arrives according to the set baud rate delay to the UART stop sending general time (for example, 11-bit format delay, delay 10.5T), and keeps the sending state if the next start bit arrives within the time T, otherwise, turns off the sending enable, and ends the data sending.

In some embodiments, in order to meet the requirement of the converter voltage, a first controller U1, a first resistor R1, a second resistor R2, and a first transistor Q1 may be disposed in the DC-DC converter 100, wherein the first controller U1 adopts an efficient PFM control method, and has the characteristics of small switching loss and small switching current less than the load current.

Specifically, a signal input end (corresponding to the LBI end) of the first controller U1 is connected with an output end (corresponding to the RS-DTR end) of the RS232 communication interface 200; the signal input end (corresponding to the REF end) of the first controller U1 is connected with the output end (corresponding to the RS-RTS end) of the RS232 communication interface 200, the 12V voltage of the output of the RS232 communication interface 200 is respectively input into the first controller U1, and is reduced to +3V or +5V voltage through the first controller U1 for output.

One end of the first resistor R1 is connected to the level terminal (+3V), and the other end of the first resistor R1 is coupled to the emitter of the first transistor Q1.

The collector of the first transistor Q1 is connected to the voltage feedback terminal (corresponding to the FB terminal) of the first controller U1 and one end of the second resistor R2, and the other end of the second resistor R2 is connected to the output terminal (corresponding to the RS-TXD terminal) of the RS232 communication interface 200.

Wherein, the resistance of the second resistor R2 is selected to be 100K.

In some embodiments, in order to stabilize the voltage value input to the first controller U1, a first inductor L1, a first capacitor C1, a second capacitor C2, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4 may be disposed in the DC-DC converter 100, wherein the diodes are zener diodes, and the first inductor L1, the first capacitor C1, and the second capacitor C2 have an energy storage function.

One end of the first inductor L1 is connected to the anode of the first diode D1, and the other end of the first inductor L1 is coupled to the power input terminal (corresponding to the V + terminal) of the first controller U1.

The cathode of the first diode D1 is connected to one end of the first resistor R1, the cathode of the second diode D2 is connected to the output end (corresponding to the RS-DTR end) of the RS232 communication interface 200, and the anode of the second diode D2 is coupled to the voltage detection end (corresponding to the LB0 end) of the first controller U1.

The cathode of the third diode D3 is connected to the output terminal (corresponding to the RS-RTS terminal) of the RS232 communication interface 200, and the anode of the third diode D3 is coupled to the reference voltage terminal (corresponding to the REF terminal) of the first controller U1.

The cathode of the fourth diode D4 is connected to the output terminal (corresponding to the RS-TXD terminal) of the RS232 communication interface 200, and the anode of the fourth diode D4 is coupled to one terminal of the second resistor R2.

The 12V voltage output by the RS232 communication interface 200 is regulated by the above-mentioned voltage regulator, then input to the DC-DC converter 100, and after being processed by the first controller U1 and the surrounding circuits, the voltage becomes a voltage of +3V or +5V and is output to the low power consumption microprocessor 300 (corresponding to the processor U3), so as to drive the low power consumption microprocessor 300 (corresponding to the processor U3) to output, receive and enable.

In some embodiments, in order to meet the requirements of half-duplex and full-duplex in the RS485 communication interface 400, a second controller U2, a fourth capacitor C4, and a fifth capacitor C5 may be disposed in the converter circuit. The performance indexes are as follows: the single power supply works at + 3V- +3.5V, the working current is 1mA, and when a load of 60 ohms is driven (when in half-duplex, the parallel value of two 120-ohm terminals is matched with the resistor), the peak current can reach 50Ma, wherein the half-duplex and full-duplex working modes are set through jumper wires.

Specifically, an input terminal (corresponding to RIIN terminal) of the second controller U2 is connected to an output terminal (corresponding to RS-TXD terminal) of the RS232 communication interface 200, and an output terminal (corresponding to TIOUT terminal) of the second controller U2 is coupled to an input terminal (corresponding to RS-RXD terminal) of the RS232 communication interface.

In some embodiments, to improve the stability of the RS485 communication interface 400, a third controller U4 and a third resistor R3 may be disposed in the converter. Specifically, an input terminal (corresponding to terminal RD) of the third controller U4 is coupled to an output terminal (corresponding to terminal RIOUT) of the second controller U2, and an input terminal (corresponding to terminals RE, DE, and DI) of the third controller U4 is coupled to an output terminal (corresponding to terminals GP0, GP1, and GP 2) of the low power microprocessor 300 (corresponding to terminal U3).

One end of the third resistor R3 is connected to the output end (corresponding to the a end) of the third controller U4, and the other end of the third resistor R3 is connected to the connection terminal (corresponding to the J1).

The specific working principle is as follows: after the low power consumption microprocessor 300 (corresponding to the U3) is reset, all the I/O ports are set as input, all the I/O port states are read, the states are stored in a register, the GP2 terminal and the GP3 terminal are changed into output states, and low level is output, so that the RS485 communication interface 400 is in a state of prohibiting receiving. The low power consumption microprocessor 300 determines the communication baud rate and the serial data format set by the user according to the initial state of the GP0, thereby presetting the internal delay setting.

After the low-power microprocessor 300 detects that the UART starts communication, the sending enable is turned on, after the internal preset delay, whether the next start bit arrives or not is detected within a wide bit time, and if so, the low-power microprocessor delays for waiting again; otherwise, the sending enable is closed, the current communication is ended, and the initial bit is detected again.

For half-duplex communication, the receive enable should be turned off before the transmit enable is allowed, and the receive enable is turned on after the transmit enable is turned off. For the full duplex communication mode, the receiving enable can be not controlled by the signal, but can be directly grounded through a jumper wire, and the receiving is always allowed.

While the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many modifications may be made by one skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An RS232 and RS485 communication interface converter is characterized by comprising a DC-DC converter, an RS232 communication interface, an RS485 communication interface and a low-power-consumption microprocessor;

2. The RS232 to RS485 communication interface converter of claim 1,

the DC-DC converter comprises a first controller, a first resistor, a second resistor and a first triode,

3. The RS232 to RS485 communication interface converter of claim 2,

the DC-DC converter further comprises a first inductor, a first diode, a second diode, a third diode and a fourth diode,

the cathode of the first diode is connected with one end of the first resistor;

4. The RS232 to RS485 communication interface converter of claim 1,

the RS485 communication interface converter comprises a second controller, the input end of the second controller is connected with the output end of the RS232 communication interface,

5. The RS232 to RS485 communication interface converter of claim 4,

the RS485 communication interface converter further comprises a third controller, wherein the input end of the third controller is coupled with the output end of the second controller;

6. The RS232 to RS485 communication interface converter of claim 5,

the RS485 communication interface converter further comprises a third resistor, one end of the third resistor is connected with the output end of the third controller, and the other end of the third resistor is connected with the wiring terminal.