CN113411241A - RS485 communication circuit, communication system and air conditioning system - Google Patents
RS485 communication circuit, communication system and air conditioning system Download PDFInfo
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- CN113411241A CN113411241A CN202110494603.1A CN202110494603A CN113411241A CN 113411241 A CN113411241 A CN 113411241A CN 202110494603 A CN202110494603 A CN 202110494603A CN 113411241 A CN113411241 A CN 113411241A
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- 238000004891 communication Methods 0.000 title claims abstract description 60
- 238000004378 air conditioning Methods 0.000 title claims abstract description 8
- 239000003990 capacitor Substances 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008054 signal transmission Effects 0.000 description 2
- 102100028680 Protein patched homolog 1 Human genes 0.000 description 1
- 101710161390 Protein patched homolog 1 Proteins 0.000 description 1
- 102100036894 Protein patched homolog 2 Human genes 0.000 description 1
- 101710161395 Protein patched homolog 2 Proteins 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/88—Electrical aspects, e.g. circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40006—Architecture of a communication node
- H04L12/40013—Details regarding a bus controller
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/403—Bus networks with centralised control, e.g. polling
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Dc Digital Transmission (AREA)
Abstract
The invention provides an RS485 communication circuit, a communication system and an air conditioning system, wherein the circuit comprises an RS485 chip and a triode; the transmitting enabling end and the receiving enabling end of the RS485 chip are connected and are both connected with the collector electrode of the triode; the collector of the triode is connected with working voltage through a first resistor, the base of the triode is connected with the sending end of the control chip, and the emitter of the triode is grounded; the data sending end of the RS485 chip is grounded, the data receiving end is connected with the receiving end of the control chip, the positive output end is connected with the pull-up resistor, and the negative output end is connected with the pull-down resistor. The invention automatically commutates through zero delay of hardware without adding IO port and using software to commutate, thereby reducing interference introduction, improving communication speed and reliability, saving hardware resource of a singlechip and simplifying software design.
Description
Technical Field
The invention relates to the technical field of RS485 communication, in particular to an RS485 communication circuit, a communication system and an air conditioning system.
Background
The existing one-to-one or many-to-many half-duplex RS485 communication circuit is realized by adopting 3 lines, except for receiving and sending two IO (Input/Output) ports, a conversion port for receiving and sending needs to be added, and a receiving and sending port of an RS485 chip is controlled by software, so that the following problems exist in the mode: 1. if the lower computer is changed into a sending state to report data after the data processing is finished, the RS485 of the upper computer cannot carry out channel switching in time due to time delay switching, and the reported data can be lost; 2. interference is easily introduced during conversion of the received and transmitted data; 3. the software and hardware resources of the single chip microcomputer are wasted.
Disclosure of Invention
The invention solves the problems that the existing RS485 chip is not timely in receiving and transmitting switching, interference is easily introduced, and single chip microcomputer resources are wasted.
In order to solve the above problems, the present invention provides an RS485 communication circuit, which includes an RS485 chip and a triode; the transmitting enabling end and the receiving enabling end of the RS485 chip are connected and are both connected with the collector electrode of the triode; the collector of the triode is connected with working voltage through a first resistor, the base of the triode is connected with the sending end of the control chip, and the emitter of the triode is grounded; the data transmitting end of the RS485 chip is grounded, the data receiving end is connected with the receiving end of the control chip, the positive output end is connected with the pull-up resistor, and the negative output end is connected with the pull-down resistor.
The RS485 communication circuit provided by the invention adopts a hardware mode for receiving and transmitting switching, the control chip can realize the switching of the access through the transmitting end, and the zero-delay automatic reversing through the hardware does not need to increase an IO port and use software for reversing, thereby reducing the introduction of interference, improving the communication speed and reliability, saving the hardware resource of a singlechip and simplifying the software design.
Optionally, an RC filter circuit is connected between the data receiving end and the receiving end of the control chip; the RC filter circuit comprises a second resistor and a first capacitor; one end of the second resistor is connected with the data receiving end, the other end of the second resistor is connected with one end of the first capacitor and the receiving end of the control chip, and the other end of the first capacitor is grounded.
The filter circuit is arranged between the data receiving end and the receiving end of the control chip, so that the high-pass filtering or low-pass filtering effect can be achieved, and the signal interference in a line is reduced.
Optionally, a third resistor is further included; one end of the third resistor is connected with the data receiving end, and the other end of the third resistor is connected with the working voltage.
According to the invention, the third resistor is arranged between the data receiving end and the working voltage, so that the working voltage after voltage reduction can be provided for the data receiving end.
Optionally, a fourth resistor is further included; one end of the fourth resistor is connected with the data transmitting end, and the other end of the fourth resistor is grounded.
According to the invention, the fourth resistor is connected between the data transmitting end and the ground, so that the data transmitting end can be grounded after voltage reduction.
Optionally, a fifth resistor is further included; one end of the fifth resistor is connected with the positive output terminal, and the other end of the fifth resistor is connected with the negative output terminal.
According to the invention, the terminal matching resistor is arranged between the output positive end and the output negative end, so that signal reflection and echo can be avoided during long-line signal transmission.
Optionally, a resistance value of the fifth resistor ranges from 100 to 140 Ω.
The invention provides a specific value of the fifth resistor, and the function of avoiding signal reflection and echo can be realized.
Optionally, the device further comprises a first thermistor and a second thermistor; the first thermistor is connected between the positive output end and the other RS485 chip, and the second thermistor is connected between the negative output end and the other RS485 chip.
The invention is connected with the thermistors between the RS485 chips and other RS485 chips, thereby realizing resistance reduction connection between chip circuits.
Optionally, a sixth resistor is further included; one end of the sixth resistor is connected with the base electrode of the triode, and the other end of the sixth resistor is connected with the receiving end of the control chip.
According to the invention, a sixth resistor is arranged between the base electrode of the triode and the receiving end of the control chip, so that the voltage reduction protection effect can be achieved.
The invention provides a communication system based on an RS485 communication circuit, which comprises the RS485 communication circuit.
The invention provides an air conditioning system which comprises the communication system based on the RS485 communication circuit.
The communication system and the air conditioning system based on the RS485 communication circuit can achieve the same technical effect as the RS485 communication circuit.
Drawings
Fig. 1 is a schematic structural diagram of an RS485 communication circuit according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
The embodiment of the invention provides an RS485 communication circuit, which comprises an RS485 chip and a triode.
The transmitting enable end DE and the receiving enable end RE of the RS485 chip U1 are connected and are both connected with the collector electrode of the triode Q1; the collector of the triode Q1 is connected with the working voltage (+5V) through the first resistor R1, the base is connected with the transmitting terminal TXD of the control chip, and the emitter is grounded. The control chip may be, for example, a single chip microcomputer. The first resistor is used for generating circuit voltage difference, and connecting the working voltage into the triode and the two enabling ends after the working voltage is reduced.
The data sending end DI of the U1 is grounded, the data receiving end RO is connected with the receiving end RXD of the control chip, the positive output end A is connected with a pull-up resistor, and the negative output end B is connected with a pull-down resistor.
In the communication circuit, a communication sending port of the control chip is directly connected to a receiving and transmitting conversion pin of an RS48 chip U1 after being inverted through a triode Q1, a data sending end DI of an RS485 chip U1 is grounded, and a data receiving end RO of the RS485 chip U1 is unchanged; the output positive terminal A and the output negative terminal B need to be matched with a pull-up resistor and a pull-down resistor.
The RS485 communication circuit provided by the invention adopts a hardware mode for receiving and transmitting switching, the control chip can realize the switching of the access through the transmitting end, and the zero-delay automatic reversing through the hardware does not need to increase an IO port and use software for reversing, thereby reducing the introduction of interference, improving the communication speed and reliability, saving the hardware resource of a singlechip and simplifying the software design.
Fig. 1 is a schematic structural diagram of an RS485 communication circuit of the present invention, showing an RS485 chip U1 and a transistor Q1.
As shown in fig. 1, an RC filter circuit is connected between the data receiving end RO and the receiving end of the control chip; the RC filter circuit comprises a second resistor R2 and a first capacitor C1.
One end of the R2 is connected with a data receiving end RO, the other end of the R2 is connected with one end of the C1 and a receiving end RXD of the control chip, and the other end of the C1 is grounded. The resistance and capacitance parameters of the RC filter circuit can be adjusted according to the specific communication rate, so as to perform high-pass filtering or low-pass filtering, and the low-pass filtering is illustrated in fig. 1 as an example.
Optionally, on the basis of the RC filter circuit, a third resistor R3 is further disposed between the data receiving end RO and the operating voltage. As shown in fig. 1, one end of R3 is connected to the data sink RO, and the other end of R3 is connected to the operating voltage. The data receiving terminal RO is connected to the operating voltage through R3, and the stepped-down operating voltage may be provided to the data receiving terminal RO.
As shown in fig. 1, a fourth resistor R4 is connected between the data transmitting terminal DI and the ground. As shown in fig. 1, one end of R4 is connected to the data transmitting terminal DI, and the other end of R4 is grounded. The R4 is also connected between the data transmitting terminal DI and the ground, so that the data transmitting terminal DI can be grounded after being stepped down.
Optionally, a fifth resistor R5 is further disposed between the output positive terminals a and B, the resistor R5 is a terminal matching resistor, as shown in fig. 1, one end of R5 is connected to the output positive terminal a, and the other end of R5 is connected to the output negative terminal B.
The terminal matching resistor is not required to be used in low-speed and short-distance communication generally, and is required to be accessed to a terminal at a receiving end in order to avoid signal reflection and echo in long-line signal transmission, wherein the terminal resistor is generally between 100 and 140 omega, and the typical value is 120 omega.
Optionally, the output positive terminal a and the output negative terminal B are respectively connected with another RS485 chip through a thermistor. As shown in fig. 1, the first thermistor PTC1 is connected between the output positive terminal a and another RS485 chip, and the second thermistor PTC2 is connected between the output negative terminal B and another RS485 chip. Wherein the thermistor can be replaced by a resistor. By connecting the thermistors, resistance reduction connection among chip circuits can be realized.
Optionally, the base of the Q1 is connected to the control chip through a sixth resistor R6. As shown in fig. 1, one end of R6 is connected to the base of the transistor, and the other end of R6 is connected to the receiving terminal RXD of the control chip. And a sixth resistor is arranged between the base of the Q1 and the control chip to play a role in voltage reduction protection.
Based on the RS485 communication circuit shown in FIG. 1, the working principle is as follows:
receiving data: TXD is high and inverted to low by Q1, the RS-485 chip receives permission, and RXD data is determined by A, B differential signals generated by other machines of the communication network.
And (3) sending data: when the TXD is transmitting low, inverted by Q1, DE/-RE is high, transmission is allowed, and since DI is grounded, the output A, B of the 485 chip generates a differential signal indicating low, and the RS485 chip in communication with this RS485 chip in the network can receive low if it is in a receiving state.
When the TXD sends a high level, the TXD is inverted through Q1, DE/-RE is a low level, the RS485 chip is in a receiving state, the A, B end of the RS485 chip is in an input state, positive differential signals are generated on the bus by the pull-down and pull-up action of resistors R8 and R7, and if the RS485 chip which is positioned in the network and communicated with the RS485 is in a receiving state, the RO pin can receive the high level.
Based on the RS485 communication circuit, the program does not need to use an instruction to control the DE/-RE to carry out the conversion of receiving and sending, the conversion is automatically completed by hardware, the function of controlling the direction by sending data is completely realized, when the data is sent, the channel is automatically in a sending state, and after the sending is stopped, the channel is automatically in a receiving state. When two transmitters transmit simultaneously, bus collision is caused, correct data cannot be received, and the circuit cannot be damaged.
According to the RS485 communication circuit, the communication sending port of the main control chip is directly connected to the receiving and transmitting conversion pin of the RS485 chip after the phase of the communication sending port is reversed through the triode; the data sending port is grounded through a resistor, the resistance value of the resistor can be adjusted as required, the pin A needs to be matched with a pull-up resistor, and the pin B needs to be matched with a pull-down resistor. The receiving and sending switching adopts a hardware mode, software is not needed to participate in reversing, no time delay is basically realized, and the communication speed is improved; saving single chip resources, reducing IO ports on hardware, simplifying software design and improving efficiency.
The RS485 communication circuit can be used for one-to-one communication and can also be used for networking communication.
The embodiment of the invention also provides a communication system based on the RS485 communication circuit, which comprises the RS485 communication circuit.
The embodiment of the invention also provides an air conditioning system which comprises the communication system based on the RS485 communication circuit.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. An RS485 communication circuit is characterized by comprising an RS485 chip and a triode;
the transmitting enabling end and the receiving enabling end of the RS485 chip are connected and are both connected with the collector electrode of the triode; the collector of the triode is connected with working voltage through a first resistor, the base of the triode is connected with the sending end of the control chip, and the emitter of the triode is grounded;
the data transmitting end of the RS485 chip is grounded, the data receiving end is connected with the receiving end of the control chip, the positive output end is connected with the pull-up resistor, and the negative output end is connected with the pull-down resistor.
2. The RS485 communication circuit of claim 1, wherein an RC filter circuit is connected between the data receiving terminal and the receiving terminal of the control chip;
the RC filter circuit comprises a second resistor and a first capacitor;
one end of the second resistor is connected with the data receiving end, the other end of the second resistor is connected with one end of the first capacitor and the receiving end of the control chip, and the other end of the first capacitor is grounded.
3. The RS485 communication circuit of claim 1, further comprising a third resistor; one end of the third resistor is connected with the data receiving end, and the other end of the third resistor is connected with the working voltage.
4. The RS485 communication circuit of claim 1, further comprising a fourth resistor; one end of the fourth resistor is connected with the data transmitting end, and the other end of the fourth resistor is grounded.
5. The RS485 communication circuit of claim 1, further comprising a fifth resistor; one end of the fifth resistor is connected with the positive output terminal, and the other end of the fifth resistor is connected with the negative output terminal.
6. The RS485 communication circuit of claim 5, wherein the resistance of the fifth resistor ranges from 100 Ω to 140 Ω.
7. The RS485 communication circuit of claim 1, further comprising a first thermistor and a second thermistor;
the first thermistor is connected between the positive output end and the other RS485 chip, and the second thermistor is connected between the negative output end and the other RS485 chip.
8. The RS485 communication circuit of claim 1, further comprising a sixth resistor; one end of the sixth resistor is connected with the base electrode of the triode, and the other end of the sixth resistor is connected with the receiving end of the control chip.
9. A communication system based on an RS485 communication circuit, characterized in that it comprises an RS485 communication circuit according to any of claims 1-8.
10. An air conditioning system, characterized in that it comprises a communication system based on an RS485 communication circuit according to claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494603.1A CN113411241A (en) | 2021-05-07 | 2021-05-07 | RS485 communication circuit, communication system and air conditioning system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494603.1A CN113411241A (en) | 2021-05-07 | 2021-05-07 | RS485 communication circuit, communication system and air conditioning system |
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| CN113411241A true CN113411241A (en) | 2021-09-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202110494603.1A Pending CN113411241A (en) | 2021-05-07 | 2021-05-07 | RS485 communication circuit, communication system and air conditioning system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114237102A (en) * | 2021-12-03 | 2022-03-25 | 珠海格力电器股份有限公司 | Communication state switching circuit and equipment |
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| CN204965418U (en) * | 2015-10-14 | 2016-01-13 | 深圳益邦阳光有限公司 | Novel RS -485 interface drive circuit |
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| CN205160512U (en) * | 2015-12-14 | 2016-04-13 | 威胜集团有限公司 | RS485 circuit and metering device who makes with this circuit |
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| CN211759027U (en) * | 2019-12-27 | 2020-10-27 | 无锡信捷电气股份有限公司 | Control system of PLC manual control box for wire cutting |
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2021
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| CN103441780A (en) * | 2013-08-16 | 2013-12-11 | 北京汉柏科技有限公司 | Communication circuit capable of enabling direction of RS-485 chip to be automatically changed |
| CN204965418U (en) * | 2015-10-14 | 2016-01-13 | 深圳益邦阳光有限公司 | Novel RS -485 interface drive circuit |
| CN205142203U (en) * | 2015-11-23 | 2016-04-06 | 无锡隆玛科技股份有限公司 | Automatic transceiver circuits of RS485 |
| CN205160512U (en) * | 2015-12-14 | 2016-04-13 | 威胜集团有限公司 | RS485 circuit and metering device who makes with this circuit |
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| CN114237102A (en) * | 2021-12-03 | 2022-03-25 | 珠海格力电器股份有限公司 | Communication state switching circuit and equipment |
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Application publication date: 20210917 |