CN216281977U - Communication circuit and air conditioner - Google Patents

Abstract

The utility model discloses a communication circuit and an air conditioner, relates to the technical field of communication, and aims to overcome the technical problems that the standby power consumption of the communication circuit is increased, the amplitude of a high-frequency signal is reduced and the like caused by matching resistors in the communication circuit. The communication circuit includes: a first node and a bus. A first control module in the first node is connected with a first communication interface module and transmits data by using a bus; a first end of a first matching resistor in the first node is connected with a first signal line of the bus, a second end of the first matching resistor is connected with a first end of a first switch module, and a second end of the first switch module is connected with a second signal line of the bus; the first switch module is opened or closed according to the state of data transmission of the first control module. The communication circuit and the air conditioner disclosed by the utility model are used for avoiding the defects that the standby power consumption of the communication circuit is increased, the amplitude of a high-frequency signal is reduced and the like caused by the matching resistance in the communication circuit.

Description

Communication circuit and air conditioner

Technical Field

The utility model relates to the technical field of communication, in particular to a communication circuit and an air conditioner.

Background

The multi-split central air conditioner may include one outdoor unit and a plurality of indoor units. The outdoor Unit and the indoor Unit are provided with a Microcontroller Unit (MCU) and communication interface chips, and the MCUs are connected to the bus through the communication interface chips in a hand-in-hand serial connection mode to form a communication network of the multi-split central air conditioner. The outdoor unit or the indoor unit on the bus can be called as a node on the bus. Data is typically transmitted between nodes in the form of high frequency signals.

When a high-frequency signal is transmitted on a bus, if the characteristic impedance of the bus is not matched with the load impedance, the high-frequency signal forms a reflected signal when being transmitted to the tail end of the bus, and the quality of the transmitted high-frequency signal is influenced. In practical application, a matching resistor is added to the first node and the tail node of the bus respectively to match the characteristic impedance of the bus with the load impedance, so as to improve the reflection problem.

However, the connection mode of the matching resistor in the circuit structure in the related art may cause a series of problems such as an increase in standby power consumption of the first node and the last node of the bus, a reduction in amplitude of the high-frequency signal, a reduction in signal-to-noise ratio of the high-frequency signal, and a reduction in interference rejection.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide a communication circuit and an air conditioner, and aims to solve the technical problem of how to avoid the defects that standby power consumption of the communication circuit is increased, the amplitude of a high-frequency signal is reduced and the like caused by a matching resistor in the communication circuit.

To achieve the above object, the present invention provides a communication circuit comprising: a first node and a bus; the first node comprises: the device comprises a first control module, a first communication interface module, a first matching resistor and a first switch module; the bus includes: a first signal line and a second signal line;

the input end of the first control module is connected with the first end of the first communication interface module, and the output end of the first control module is connected with the second end of the first communication interface module; the third end of the first communication interface module is connected with the first signal line, and the fourth end of the first communication interface module is connected with the second signal line; a first end of the first matching resistor is connected with the first signal line, a second end of the first matching resistor is connected with a first end of the first switch module, and a second end of the first switch module is connected with the second signal line;

the first control module is used for transmitting data with other nodes on the bus through the first communication interface module;

and the first switch module is used for switching off or switching on according to the state of the data transmitted by the first control module.

The utility model has the beneficial effects that: the first switch module is switched off or switched on according to the state of the first control module for transmitting data, so that the reflection problem in the communication circuit is avoided, and meanwhile, when the first control module sends data, the resistance value of the load of the first communication interface module is smaller than that of the first matching resistor, so that the derivative problem caused by the fact that the first matching resistor is used as the load of the first communication interface module is avoided.

On the basis of the technical scheme, the utility model can be further improved as follows.

Further, a first control end of the first control module is connected with a control end of the first switch module; the first control module is used for controlling the first switch module to be switched off or switched on according to the state of data transmission of the first control module.

Further, the first node further comprises: a second control module; the first control end of the first control module is connected with the first end of the second control module, and the second end of the second control module is connected with the control end of the first switch module;

and the second control module is used for controlling the first switch module to be switched off or switched on according to the state of the data transmitted by the first control module.

Further, the first control end of the first control module is connected with the data transmission enabling end of the first communication interface module.

Further, the bus is an RS485 bus or a CAN bus.

Further, the first node further comprises: at least one second matching resistance;

the first end of each second matching resistor is connected with the first end of the first matching resistor, and the second end of each second matching resistor is connected with the second end of the first switch module.

Further, the first node further comprises: a first capacitor and a second capacitor;

the first capacitor is connected in series with the first signal line, and a first end of the first capacitor is connected with a first end of the first matching resistor; the second capacitor is connected in series with the second signal line, wherein a first end of the second capacitor is connected with a second end of the first switch module.

Further, the first control end of the first control module is a data sending end of the first control module.

Further, the bus is a homebus bus.

Further, the communication circuit includes two first nodes, where one first node is a head node on the bus and the other first node is a tail node on the bus.

Further, the communication circuit further includes: at least one second node; the second node is an intermediate node on the bus, and the second node comprises: the third control module and the second communication interface module;

the input end of the third control module is connected with the first end of the second communication interface module, the output end of the third control module is connected with the second end of the second communication interface module, the third end of the second communication interface module is connected with the first signal line of the bus, and the fourth end of the second communication interface module is connected with the second signal line.

The utility model also provides an air conditioner which comprises the communication circuit according to any technical scheme.

The beneficial effects of the present invention are the same as those of the communication circuit described above, and are not described herein again.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic structural view of an air conditioner in the related art;

FIG. 2 is a waveform diagram of a high frequency signal;

fig. 3 is a schematic structural diagram of a communication circuit provided in the present application;

fig. 4 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 5 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 6 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 7 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 8 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 9 is a schematic structural diagram of another communication circuit provided in the present application;

fig. 10 is a schematic structural diagram of another communication circuit provided in the present application.

Detailed Description

Fig. 1 is a schematic structural diagram of an air conditioner in the related art. As shown in fig. 1, taking a multi-split central air conditioner as an example, the multi-split central air conditioner includes an outdoor unit and a plurality of indoor units. Fig. 1 is a schematic view of 3 indoor units as an example, and the indoor units 1, 2, and 3 are illustrated.

At present, both the outdoor Unit and the indoor Unit are provided with a Microcontroller Unit (MCU) and a communication interface chip, and each MCU is connected to a bus by the communication interface chip in a manner of serial connection by a hand, so as to form a communication network of the multi-split central air conditioner. Through the formed communication network, data interaction can be carried out between the outdoor unit and the indoor unit through a bus so as to realize the control of refrigeration or heating. For example, the MCU of the indoor unit may transmit parameters (e.g., temperature, operation mode, etc.) set by a user to the MCU of the outdoor unit, so that the MCU of the outdoor unit may control the compressor and the fan of the air conditioner based on the parameters.

In general, the outdoor unit is a master unit of the multi-split central air conditioner, and the indoor units are slave units of the multi-split central air conditioner, so in the communication network, the outdoor unit is usually located at the head end of the bus, and is a head node on the bus, the indoor units located at the tail end of the serial connection are tail nodes on the bus, and the rest of the indoor units are intermediate nodes on the bus. In the example shown in fig. 1, the indoor unit 3 is the tail node on the bus, and the indoor unit 1 and the indoor unit 2 are the middle nodes on the bus.

The bus involved in the communication Network may be, for example, an RS485 bus, a Controller Area Network (CAN) bus, a Homebus, or the like. Fig. 1 is a schematic diagram of an RS485 bus as an example.

Fig. 2 is a waveform diagram of a high-frequency signal, and as shown in fig. 2, a node on a bus generally transmits data in the form of a high-frequency signal, or the high-frequency signal transmitted by the node carries data. The high frequency signal may also be referred to as a high frequency voltage signal, or a high frequency alternating voltage signal. In the present application, the meaning of transmitting a high frequency signal is equivalent to that of transmitting data, and the present application does not distinguish between these.

When a high frequency signal is transmitted on the bus, if the characteristic impedance of the bus is not equal to (i.e., not matched with) the load impedance, i.e., the impedance is discontinuous, the high frequency signal forms a reflected signal when being transmitted to the end of the bus. The reflected signal is superimposed with the originally transmitted high-frequency signal, which causes distortion of the waveform of the high-frequency signal and affects the quality of the transmitted high-frequency signal.

With continued reference to fig. 1, in practical applications, a matching resistor (R1 and R2, respectively) is typically added to the first node and the last node of the bus to match the characteristic impedance of the bus to the load impedance, thereby improving the above-mentioned reflection problem. For example, when the outdoor unit transmits data, the matching resistor R2 prevents the high frequency signal from being reflected by the indoor unit 3. When the indoor unit located at the end of the bus transmits data, the high frequency signal is prevented from being reflected at the outdoor unit by the matching resistor R1.

The resistance value of the matching resistor can be determined according to the characteristic impedance (i.e. characteristic impedance) of the cable of the bus. For example, when the RS485 bus and the CAN bus are used, the characteristic impedance of the cable of the RS485 bus and the CAN bus is 120 ohms (Ω), and therefore, the resistance values of the matching resistors R1 and R2 may be 120 Ω, for example.

Although the reflection problem can be improved by increasing the matching resistor, the matching resistor is connected in the circuit structure in such a way that the matching resistor becomes a load of a driver in the corresponding communication interface chip (i.e., a device for transmitting a high-frequency signal to a bus in the communication interface chip), or the matching resistor becomes a load of the node, and the following two problems arise:

1. the driving current of the communication interface chip is increased, the driving voltage drop of the communication interface chip is increased, and the standby power consumption of the first node and the tail node is increased.

2. The amplitude of the transmitted high-frequency signal is reduced, the longest communication distance on the bus is further reduced, and the number of nodes connected in series on the bus is reduced. In addition, the signal-to-noise ratio of the high-frequency signal is reduced, and the anti-interference capability is weakened.

The inventor finds that when the head node on the bus transmits data, the matching resistance at the tail node improves the reflection problem, and conversely, when the tail node transmits data, the matching resistance at the head node improves the reflection problem. That is, the presence or absence of a matching resistance at the node has no effect on improving the reflection problem when the node is transmitting data.

In view of the above, the present application provides a communication circuit, which is configured to a node having a matching resistor, and is capable of disconnecting the matching resistor of the node when the node transmits data, so as to avoid the derivative problem caused by the matching resistor as a load.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

Fig. 3 is a schematic structural diagram of a communication circuit provided in the present application, and as shown in fig. 3, the communication circuit includes: a first node and a bus.

The bus may include: a first signal line and a second signal line. The bus mentioned here may be, for example, an RS485 bus, a CAN bus, or a Homebus bus.

The first node may be any node in the communication circuit at which a matching resistance is provided, for example, a first node or a tail node in the communication circuit. Taking the communication circuit as an example of being applied to a multi-split central air conditioner, the first node may be, for example, an outdoor unit of the multi-split central air conditioner, or an indoor unit located at an end of a serial connection bus.

The first node may include: the communication device comprises a first control module, a first communication interface module, a first matching resistor (such as a resistor R shown in figure 3) and a first switch module. The input end of the first control module is connected with the first end of the first communication interface module; the output end of the first control module is connected with the second end of the first communication interface module. The third end of the first communication interface module is connected with the first signal wire; and the fourth end of the first communication interface module is connected with the second signal line. The first end of the first matching resistor is connected with the first signal line, and the second end of the first matching resistor is connected with the first end of the first switch module. The second end of the first switch module is connected with the second signal line.

And the first control module is used for transmitting data with other nodes on the bus through the first communication interface module. The other nodes on the bus referred to herein may be, for example, at least one of nodes 1-N as shown in fig. 3. For example, the first control module may be any module having a control function, such as an MCU, a CPU, a single chip, and the like. Still taking the communication circuit as an example applied to a multi-split central air conditioner, and the first node is an outdoor unit of the multi-split central air conditioner, the first control module of the outdoor unit of the multi-split central air conditioner may transmit data with each indoor unit on the bus through the first communication interface module.

The first communication interface module may be any module that can transmit data through a bus, for example, a communication interface chip. In some embodiments, the types of the communication interface chips corresponding to the different types of buses may be the same or different. For example, the types of the communication interface chips corresponding to the RS485 bus and the CAN bus may be the same, and the types of the communication interface chips corresponding to the Homebus bus and the RS485 bus or the CAN bus may be different.

The first matching resistor can be a single resistor, or a plurality of resistors can be connected in parallel, or connected in series, or connected in parallel and in series to obtain the first matching resistor. Illustratively, the first matching resistor may have a resistance equal to a characteristic impedance of the bus line.

And the first switch module is used for opening or closing according to the state of the data transmitted by the first control module. The state of the first control module transmitting data may be a state of transmitting data, or a state of receiving data. It should be understood that the first control module described in this application may receive data at the time of actually receiving the data, or may regard all times except for the time of transmitting the data as the time of receiving the data.

Illustratively, the first switch module can be, for example, any switch capable of being closed or opened according to a control signal, such as a single-throw relay, a unidirectional electronic switch, an analog switch, and the like. The analog switch may be, for example, a transistor, a MOS transistor, a thyristor, or the like.

Optionally, the first switch module may be opened when the first control module is in a data sending state, and closed when the first control module is in a data receiving state, for example.

The first switch module is controlled to be switched off when the first control module sends data, so that the first matching resistor and the first communication interface module do not form a loop any more, and the first matching resistor is not a load of the first communication interface module any more. Since the driving current and the driving voltage of the first communication interface module are positively correlated with the load size of the first control module when sending data, the load of the first node is reduced when the first control module sends data, the driving current and the driving voltage of the first communication interface module can be reduced, and the standby power consumption of the first node can be reduced. In addition, because the load of the first node is reduced when the first control module sends data, the amplitude of the sent high-frequency signal can be increased, the signal-to-noise ratio and the anti-interference capability of the high-frequency signal are improved, the longest communication distance on the bus can be further increased, and the number of nodes connected in series on the bus is increased.

The first switch module is controlled to be closed when the first control module receives data, so that the first matching resistor and the first communication interface module form a loop, and the first matching resistor is used as a load of the first communication interface module. By using the first matching resistor as the load of the first communication interface module, the load impedance of the first node can be matched with the characteristic impedance of the cable of the bus, so that when the first control module receives data, the data cannot form a reflected signal, and the quality of the first control module for receiving the data is improved.

Or, if the first node further includes a second matching resistor having one end connected to the first end of the first matching resistor and the other end connected to the second end of the first switch module, the first switch module may be turned on when the first control module is in a data transmitting state and turned off when the first control module is in a data receiving state.

In this embodiment, the first switch module is turned off or turned on according to the state of the first control module transmitting data, so that the reflection problem in the communication circuit is avoided, and meanwhile, when the first control module transmits data, the load resistance of the first communication interface module is smaller than the resistance of the first matching resistor, thereby avoiding the derivative problem caused by the first matching resistor serving as the load of the first communication interface module.

The following is a detailed description of how to control the opening or closing according to the state of the data transmitted by the first control module:

as a possible implementation manner, the first control module may directly control the first switch module to be turned off or turned on according to a state of the first control module transmitting data. For example, fig. 4 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 4, the first control terminal of the first control module may be connected to the control terminal of the first switch module. In this implementation manner, the first control module may be configured to control the first switch module to be opened or closed according to a state of the first control module transmitting data. For example, the first control module may control the first switch module to open when the first control module transmits data. And when the first control module receives the data, the first switch module is controlled to be closed. Or, the first control module may further control the first switch module to be closed when detecting that a rising edge signal exists in data sent by the first control module.

The first control module can control the first switch module to be switched off when the first control module sends data; for example, when the first control module receives data, the first control module may send a signal capable of driving the relay to close to control the relay to close, so that a loop formed by the first matching resistor and the first communication interface module is closed. Optionally, when sending data, the first control module may not send a driving signal to the relay, or send a signal that cannot drive the relay to close, so as to control the relay to open.

It should be understood that the present application is not limited to the type of relay described above. Illustratively, the relay may be, for example, a current relay or a voltage relay. The driving signal sent by the first control module to the relay is matched with the type of the relay. For example, taking the relay as a current relay, the first control module may output a current greater than or equal to a preset current threshold to the current relay when receiving data, so as to control the relay to close. The first control module may output no current to the current relay or output a current less than a preset current threshold to control the relay to open when transmitting data. Wherein, the preset current threshold is the closing threshold of the current relay.

The first control module can control the first switch module to be switched off when the first control module sends data; for example, taking the first switch module as an analog switch as an example, the first control module may send a signal indicating that the analog switch is closed to control the relay to be closed when receiving data, so that a loop formed by the first matching resistor and the first communication interface module is closed. Optionally, when sending data, the first control module sends a signal to the analog switch, where the signal indicates that the analog switch is turned off, so as to control the relay to be turned off.

It should be understood that the present application is also not limited to the type of signal used to indicate the closing or opening of the analog switch described above. For example, the signal for indicating the closing or opening of the analog switch may be an analog voltage signal, or an analog current signal, for example. Taking the analog current signal as an example, the magnitude of the analog current signal for indicating the closing of the analog switch and the magnitude of the analog current signal for indicating the opening of the analog switch may be different.

In the embodiment, the first control module directly controls the first switch module to be switched on or off according to the state of the data transmitted by the first control module, so that the derived problems caused by the first matching resistor as a load are avoided, the complexity of the communication circuit is not changed, the probability of the communication circuit being in fault is reduced, and the cost of the communication circuit is saved.

As another possible implementation manner, when the signal output by the first control end of the first control module is not matched with the signal for controlling the first switch module to be opened or closed, the second control module may further control the first switch module to be opened or closed according to the state of the data transmitted by the first control module.

For example, fig. 5 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 5, the first node may further include: and a second control module. The first control end of the first control module is connected with the first end of the second control module, and the second end of the second control module is connected with the control end of the first switch module. In some embodiments, the first control end of the first control module and the output end of the first control module may also be the same port, and fig. 5 is only an exemplary illustration of different ports at the end of the first control module and the output end of the first control module.

Optionally, the second control module may control the first switch module to be turned off when it is determined that the first control module sends data; and controlling the first switch module to be closed when the first control module is determined to receive the data. Or, the second control module may also control the first switch module to be closed when it is determined that the first control module receives the data; and controlling the first switch module to be switched off when the first control module is determined to send data.

Taking the first switch module for being turned off when the first control module is in the data sending state as an example, the aforementioned "the signal output by the first control end of the first control module does not match the signal for controlling the first switch module to be turned off" may be, for example: when the first control module is in a data sending state, the strength of a signal output by a first control end of the first control module is greater than (or less than) the strength of a signal for controlling the first switch module to be switched off; or, the first control end of the first control module outputs a high level signal, and the signal for controlling the first switch module to be switched off is a low level signal; or, the output of the first control end of the first control module is a low level signal, and the signal for controlling the first switch module to be switched off is a high level signal.

When the first control module is in a data sending state, the second control module can convert a signal output by the first control end of the first control module into a signal for controlling the first switch module to be switched off so as to control the first switch module to be switched off. When the first control module is in a data receiving state, the second control module may convert a signal output by the first control end of the first control module into a signal for controlling the first switch module to be closed, so as to control the first switch module to be closed.

Optionally, the second control module may be any module having a control function, such as an MCU, a CPU, a single chip microcomputer, and the like.

Alternatively, the second control module may be, for example, a device capable of amplifying (or reducing) the intensity of the signal output by the first control terminal of the first control module to obtain a signal having the same intensity as the intensity of the signal for controlling the first switch module to be turned off, such as a signal scaling device. Optionally, the type of the signal scaler may be matched with the type of the signal output by the first control terminal of the first control module, for example. Taking the signal output by the first control end of the first control module as a current signal with a current value smaller than the current value for controlling the first switch module to be switched off as an example, the second control module may be, for example, a current signal amplifier.

Further alternatively, for example, when the first control module is in a data sending state, the signal output by the first control end of the first control module is opposite to the signal for controlling the first switch module to be turned off, and the second control module may be any device capable of inverting a high level signal into a low level signal or inverting a low level signal into a high level signal.

The following is an exemplary description of how the second control module determines the status of the first control module transmitting data:

optionally, the first control end of the first control module may be connected to a data transmission enabling end of the first communication interface module, for example. The first control end of the first control module may send a data sending enable signal to instruct sending of data through the first communication interface module by sending the data sending enable signal to the data sending enable end of the first communication interface module.

Because the first end of the second control module is also connected with the first control end of the first control module, when the first control end of the first control module sends the data sending enabling signal, the second control module can also obtain the data sending enabling signal. For example, the first switch module is configured to be turned off when the first control module is in a data sending state, and is turned on when the first control module is in a data receiving state, and the second control module may convert the data sending enable signal into a signal for controlling the first switch module to be turned off, so as to control the first switch module to be turned off. If the second control module does not acquire the data transmission enable signal, which indicates that the first control module does not transmit data, the second control module may determine that the first control module is in a data receiving state, and optionally, the second control module may control the first switch module to be turned on.

Optionally, the first communication interface module provided with the data sending enable end may be, for example, a communication interface chip corresponding to an RS485 bus, or a communication interface chip corresponding to a CAN bus. That is, in this implementation, the aforementioned bus may be, for example, an RS485 bus, or a CAN bus, etc.

In this example, the first control end of the first control module is connected to the data transmission enabling end of the first communication interface module, so that the first switch module is controlled to be switched off or switched on according to the data transmission state of the first control module, and meanwhile, the port of the first control module is not occupied additionally, and the occupation of the first control module resource is reduced.

Optionally, the first control end of the first control module may be connected to a data receiving enable end of the first communication interface module, for example. The first control end of the first control module may send a data reception enable signal to the data reception enable end of the first communication interface module to instruct to receive data through the first communication interface module. Because the first end of the second control module is also connected with the first control end of the first control module, when the first control end of the first control module sends the data receiving enabling signal, the second control module can also obtain the data receiving enabling signal. For example, the first switch module is configured to be turned off when the first control module is in a data sending state, and turned on when the first control module is in a data receiving state, and the second control module may convert the data receiving enable signal into a signal for controlling the first switch module to be turned on, so as to control the first switch module to be turned on. If the second control module does not acquire the data reception enable signal, it is indicated that the first control module does not receive data, and optionally, the second control module may control the first switch module to be turned off.

In this embodiment, the second control module controls the first switch module to be turned on or off according to the state of the data transmitted by the first control module, so that the second control module corresponding to the first switch module can be set for different types of first switch modules, thereby improving the flexibility of the communication circuit.

Example two

Further, the inventor finds, through research, that there are some types of buses, such as a homebus bus, where the first communication interface module is in a high impedance state when the signal sent by the corresponding first control module is a high level signal, and the first communication interface module is in a non-high impedance state when the signal sent by the corresponding first control module is a low level signal. When the signal sent by the first control module changes from a low-level signal to a high-level signal, that is, when the signal sent by the first control module is a rising edge, the first communication interface module changes from a non-high impedance state to a high impedance state, and at this time, there may be a short-time spike in the signal sent by the first control module to cause signal abnormality. The inventor finds that when the signal sent by the first control module is a rising edge, the resistance value of the matching resistor in the first node is reduced, and short-time spikes appearing in the signal sent by the first control module can be reduced.

Thus, as a possible implementation, the first node of the communication circuit may further comprise at least one second matching resistance. For example, taking the first node of the communication circuit includes a second matching resistor as an example, fig. 6 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 6, optionally, wherein each second matching resistance (R as shown in fig. 6)_{Second one}) Is connected to a first end of the first matching resistor and a second end of each second matching resistor is connected to a second end of the first switch module. It should be understood that the resistance of the second matching resistor may be the same as or different from the resistance of the first matching resistor.

In this implementation manner, optionally, the first switch module may be closed when the state of the first control module transmitting data is sending data; and when the state of the first control module transmitting data is receiving data, the first control module is disconnected.

The first switch module is closed when the first control module transmits data in a data transmission state, so that the first matching resistor and the second matching resistor are connected in parallel, and the obtained resistance value of the first matching resistor and the second matching resistor connected in parallel is used as the resistance value of the matching resistor in the first node. And the total resistance value of any two resistors after being connected in parallel is smaller than the resistance value of any one of the two resistors. Therefore, the resistance value of the first matching resistor and the resistance value of the second matching resistor after being connected in parallel are used as the resistance value of the matching resistor in the first node, so that the resistance value of the matching resistor in the first node can be reduced, the standby power consumption of the first node is reduced, the amplitude of a transmitted high-frequency signal is increased, the signal-to-noise ratio and the anti-interference capability of the high-frequency signal are improved, the resistance value of the matching resistor in the first node can be reduced, when a rising edge signal exists in data transmitted by the first control module, the probability of short-time spikes appearing in the data is reduced, and the stability of the data transmitted by the first control module is improved.

The first switch module is disconnected when the first control module transmits data and receives the data, so that the resistance value of the matching resistor in the first node is equal to the resistance value of the second matching resistor. The second matching resistor is used as the load impedance of the first node, so that when the first control module receives data, the data cannot form a reflection signal, and the data receiving quality of the first control module is improved.

As a possible implementation manner, the first control end of the first control module may be used as a data sending end of the first control module. The data sending end of the first control module can be directly connected with the control end of the first switch module to control the first switch module to be closed when the state that the first control module transmits data is sending data and to be opened when the state that the first control module transmits data is receiving data. Or, the data sending end of the first control module may be further connected to the second control module, and the second control module may control the first switch module to be turned on when the state of data transmission by the first control module is sending data, and to be turned off when the state of data transmission by the first control module is receiving data.

It should be understood how to make the first switch module close when the state of the first control module transmitting data is transmitting data; for a specific implementation manner of the disconnection when the state of the data transmission of the first control module is receiving data, the implementation manner of how to control the disconnection or the connection according to the state of the data transmission of the first control module in the foregoing embodiment may be referred to, and details are not described herein again.

Further, as a possible implementation manner, considering that on some types of buses, such as a homebus bus, the transmitted signals may include direct current signals and alternating current signals, the first node may further include: a first capacitor and a second capacitor. For example, fig. 7 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 7, the first capacitor (e.g., capacitor C1 shown in fig. 7) may be connected in series with the first signal line. The first end of the first capacitor is connected to the first end of the first matching resistor. A second capacitor (e.g., capacitor C2 shown in fig. 7) may be connected in series with the second signal line, and a first terminal of the second capacitor may be connected to the second terminal of the first switch module.

Because the main alternating current signal that carries effective information, and direct current signal often does not carry effective information, consequently, through establishing ties first electric capacity on first signal line, establish ties the second electric capacity on the second signal line, can use this first electric capacity and second electric capacity to filter the signal on the bus, the direct current signal on the filtering bus, make the signal that this first control module received through this bus or the signal that sends through this bus be alternating current signal, the utilization ratio of bus has been improved and direct current signal has been avoided the influence to alternating current signal, and then each node on the bus has been improved and has carried out relevant operation's accuracy according to this alternating current signal.

EXAMPLE III

In some embodiments, the communication circuit may include two first nodes. Optionally, one of the first nodes may be a head node on the bus, and the other first node may be a tail node on the bus. Taking the communication circuit shown in fig. 3 as an example, the node N (tail node on the bus) in the communication circuit may be the aforementioned another first node. Still taking the communication circuit as an example for application to a multi-split central air conditioner, for example, one of the first nodes may be, for example, an outdoor unit of the multi-split central air conditioner, and the other first node may be, for example, an indoor unit connected to an end of the bus.

In this embodiment, the first node and the last node on the bus are both set as the first node, so that whether data is sent to the last node through the first node on the bus or the last node sends data to the first node, the problem of reflection caused by the first node is avoided in the communication circuit, and meanwhile, the load of the first node is reduced when the first control module sends data, so that the problem of derivation caused by the first matching resistor as a load is avoided, the power consumption of the communication circuit is further reduced, the amplitude of the sent high-frequency signal is further increased, and the signal-to-noise ratio and the anti-interference capability of the high-frequency signal are improved.

Optionally, the communication circuit may further include: at least one second node. Wherein any one of the second nodes is an intermediate node on the bus. Taking the communication circuit shown in fig. 3 as an example, the intermediate node in the communication circuit, such as node 1, may be the second node. The second node may include: a third control module, and a second communication interface module. For example, taking the communication circuit includes two second nodes as an example, fig. 8 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 8, the input terminal of the third control module may be connected to the first terminal of the second communication interface module. An output of the third control module may be connected to a second terminal of the second communication interface module. The third end of the second communication interface module can be connected with the first signal line of the bus, and the fourth end of the second communication interface module is connected with the second signal line.

In some embodiments, the third control module may be the same as or different from the first control module. Optionally, in a specific implementation, the type of the third control module may be determined according to a function that the second node needs to implement. The second communication interface module may be the same as or different from the first communication interface module. Optionally, in a specific implementation, the type of the second communication interface module may be determined according to a function that the second node needs to implement.

It should be understood that the present application is not limited to whether the second node further includes other modules. Illustratively, the second node may further include a third matching impedance, and a second switching module, for example. In this implementation manner, the third matching impedance, and the connection manner and the function of the second switch module in the second node may refer to the first node described in the foregoing embodiment, and are not described herein again.

Still taking the communication circuit as an example applied to a multi-split central air conditioner, the second node may be, for example, each indoor unit of the multi-split central air conditioner connected to the bus.

In this embodiment, by providing at least one second node in the communication circuit, data transmission can be performed between the first node and the at least one second node, so that the flexibility and the application range of the communication circuit are improved.

Example four

Taking an RS485 bus or a CAN bus as an example, fig. 9 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 9, the communication circuit may include two first nodes. One of the first nodes is a head node of the bus, and the other first node is a tail node of the bus. The communication circuit may further comprise at least one second node (fig. 9 is an example in which the communication circuit comprises two second nodes).

For any first node, the first control module of the first node may be an MCU, and the first communication interface module may be a first communication interface chip. The first communication interface chip may include an RO (port through which the first communication interface chip receives a signal), an RE (receive enable port through which the first communication interface chip receives a signal), a DE (transmit enable port through which the first communication interface chip transmits a signal), a DI (port through which the first communication interface chip transmits a signal), a VCC (port through which power is supplied to the first communication interface chip), a B (port through which the first communication interface chip is connected to the first signal line), a (port through which the first communication interface chip is connected to the second signal line), and a GND (ground port through which the first communication interface chip is connected). The meaning of the respective port identifications of the communication interface chip shown in fig. 1 is the same as here.

For any second node, the third control module of the second node may also be an MCU. The second communication interface chip may be the same as the first communication interface chip (for a more concise description, other ports of the second communication interface are omitted from fig. 9).

In this implementation, as shown in an example shown by two dotted lines in fig. 9, the MCU may be directly connected to the first switch module, and the first switch module is controlled to be turned off when the MCU transmits data and turned on when the MCU receives data. Or the MCU can be further connected with a second control module, and the second control module can control the first switch module to be switched off when the MCU sends data and to be switched on when the MCU receives data.

Taking the homebus as an example, fig. 10 is a schematic structural diagram of another communication circuit provided in the present application. As shown in fig. 10, the communication circuit may also include two first nodes. One of the first nodes is a head node of the bus, and the other first node is a tail node of the bus. Optionally, the communication circuit may further comprise at least one second node (not shown in fig. 10). Each first node includes a first matching resistor R2, and a second matching resistor R1, as well as a capacitor connected in series with the first signal line and a capacitor connected in series with the second signal line.

For any first node, the first control module of the first node may be an MCU, and the first communication interface module may be a Homebus interface chip. The Homebus interface chip may include Din (a port of the first communication interface chip to receive a signal), Dout (a receive enable of the first communication interface chip), a (in/out) (a transmit enable of the first communication interface chip), B (in/out) (a port of the first communication interface chip to transmit a signal).

In this implementation, as shown in fig. 10 as an example, the MCU may be connected to a second control module (e.g., a control circuit shown in fig. 10), and the control circuit may control the first switch module (e.g., S1 shown in fig. 10) to be turned on when the MCU transmits data and to be turned off when the MCU receives data.

The embodiment of the utility model also provides an air conditioner, which comprises the communication circuit provided by any one of the previous embodiments. Illustratively, the air conditioner may be a central air conditioner, such as a multi-split central air conditioner. The air conditioner has the technical effect similar to that of the communication circuit, and the description is omitted. It should be understood that the air conditioner may also include other components, such as a fan, a compressor, etc., for example, and is not limited thereto.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the utility model has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (12)

1. A communication circuit, the communication circuit comprising: a first node and a bus; the first node comprises: the device comprises a first control module, a first communication interface module, a first matching resistor and a first switch module; the bus includes: a first signal line and a second signal line;

the input end of the first control module is connected with the first end of the first communication interface module, and the output end of the first control module is connected with the second end of the first communication interface module; the third end of the first communication interface module is connected with the first signal line, and the fourth end of the first communication interface module is connected with the second signal line; a first end of the first matching resistor is connected with the first signal line, a second end of the first matching resistor is connected with a first end of the first switch module, and a second end of the first switch module is connected with the second signal line;

the first control module is used for transmitting data with other nodes on the bus through the first communication interface module;

and the first switch module is used for switching off or switching on according to the state of the data transmitted by the first control module.

2. The communication circuit of claim 1, wherein the first control terminal of the first control module is connected to the control terminal of the first switch module; the first control module is used for controlling the first switch module to be switched off or switched on according to the state of data transmission of the first control module.

3. The communication circuit of claim 1, wherein the first node further comprises: a second control module; the first control end of the first control module is connected with the first end of the second control module, and the second end of the second control module is connected with the control end of the first switch module;

and the second control module is used for controlling the first switch module to be switched off or switched on according to the state of the data transmitted by the first control module.

4. The communication circuit according to claim 2 or 3, wherein the first control terminal of the first control module is connected to the data transmission enable terminal of the first communication interface module.

5. The communication circuit of claim 4, wherein the bus is an RS485 bus or a CAN bus.

6. The communication circuit according to any of claims 1-3, wherein the first node further comprises: at least one second matching resistance;

the first end of each second matching resistor is connected with the first end of the first matching resistor, and the second end of each second matching resistor is connected with the second end of the first switch module.

7. The communication circuit of claim 6, wherein the first node further comprises: a first capacitor and a second capacitor;

the first capacitor is connected in series with the first signal line, and a first end of the first capacitor is connected with a first end of the first matching resistor; the second capacitor is connected in series with the second signal line, wherein a first end of the second capacitor is connected with a second end of the first switch module.

8. The communication circuit of claim 7, wherein the first control terminal of the first control module is a data transmitting terminal of the first control module.

9. A communication circuit according to claim 8, wherein the bus is a homebus bus.

10. A communication circuit according to any of claims 1-3, characterized in that the communication circuit comprises two first nodes, one of which is the first node on the bus and the other of which is the last node on the bus.

11. The communication circuit of claim 10, further comprising: at least one second node; the second node is an intermediate node on the bus, and the second node comprises: the third control module and the second communication interface module;

the input end of the third control module is connected with the first end of the second communication interface module, the output end of the third control module is connected with the second end of the second communication interface module, the third end of the second communication interface module is connected with the first signal line of the bus, and the fourth end of the second communication interface module is connected with the second signal line.

12. An air conditioner characterized by comprising a communication circuit according to any one of claims 1 to 11.

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