JP6015487B2 - Frequency modulation communication terminal device - Google Patents

Description

The present invention relates to an air conditioning system and an FA network, and more particularly to a transmission signal collision detection method applied to a frequency modulation type communication terminal apparatus.

In the air conditioning system and FA (Factory Automation), the amount of communication increases when many terminals are connected, and each terminal transmits a signal after confirming that there is no signal transmitted from another terminal on the transmission path. Even if it is processed, it is difficult to avoid collision of signals on the transmission path that occurs when signals are transmitted from a plurality of terminals at the same time because of the delay time of processing by the program.

For this reason, in order to perform normal communication even if signal collision occurs, a response signal to the transmission signal is requested from the communication destination to check whether the signal is normally transmitted, and the signal is normally transmitted. There is a method of retransmitting a signal when there is not, but this method is not suitable for a network connecting many terminals because the amount of communication itself increases and collision easily occurs.

From such a background, there is a signal collision detection method for confirming that a signal transmitted from another terminal does not exist on the transmission line while the terminal is transmitting a signal. Each terminal that receives the signal transmitted from its own transmitter circuit is received by its own receiver circuit, compares the transmitted and received signals, determines that there is a signal collision when a mismatch occurs, and transmits the signal. There has been proposed a communication apparatus capable of performing retransmission after waiting for a time set so that each communication apparatus has a different value according to an agreement at the time of retransmission (for example, see Patent Document 1). ).

JP-A-8-154100 (pages 4-9, FIG. 29)

According to the communication device of Patent Literature 1, when the transmission path between communication terminal devices from signal transmission to reception is short, it is possible to determine a signal collision. However, since the voltage level attenuates as the distance of the transmission path through which the signal passes is increased, there is a problem in that a signal collision cannot be accurately detected when a long transmission path is used.

For example, in the communication device of FIG. 6 disclosed in the above publication, the data transmitted from the transmission circuit connected to the upstream transmission path and the transmission data are returned by the HE (head end) and transmitted to the downstream transmission path. The data received by the reception circuit connected to the downstream transmission path is compared by the transmission / reception data comparison circuit connected to the transmission circuit and the transmission / reception data is detected. It is like that.

However, as shown in FIG. 7 (1), when the distance of the transmission path connecting terminal A and terminal B that transmits and receives signals is long, the signal is transmitted from terminal A as shown in FIG. 7 (2). The signal maintains a high voltage level at the transmission line L1, but the voltage level gradually decreases as the transmission line distance from the terminal A increases as it passes through the transmission line L2 and L3. In the transmission line L4 near the terminal B, the voltage level is low. In the same transmission path, as shown in FIG. 7 (3), the signal transmitted from the terminal B also has a low voltage level while passing through the transmission paths L4 to L1. Thus, the voltage level of the signal is attenuated in a form proportional to the distance of the transmission line.

Here, assuming that terminals A and B in FIG. 7 transmit signals almost simultaneously, signals received when a signal collision occurs will be described. For example, the terminal A receives a signal in which the transmitted high voltage level signal and the low voltage level signal transmitted from the terminal B collide, but at the L1 point, the signal transmitted from the terminal A and the terminal B Since the difference in the voltage level becomes large, if there is a difference in the transmission level, the signal of the collision that is received by the terminal A is received by the own device due to the capturing effect that the signal with the higher transmission level is transmitted correctly. It is the same as the transmitted data. Also in terminal B, the signal generated by the collision received by terminal B is the same as the data transmitted by itself, and when the distance of the transmission path between the terminals is long, the transmission data and the received data are compared to detect the collision. May not be possible.

An object of the present invention is to solve the above-described problems and to provide a communication terminal device capable of detecting a collision of transmission data in an air conditioning system network that uses a long transmission path.

In order to solve the above-described problems, the present invention according to claim 1 of the present invention controls transmission / reception of communication data in a terminal device that performs communication using a frequency modulation method, and transmits during transmission of the communication data. A control unit that outputs a zero-cross determination signal indicating a period in which the waveform of the signal is around the zero-cross point, a transmission unit that turns off the output of the transmission signal according to the zero-cross determination signal, and the terminal device and the transmission path A communication data input / output terminal for connecting and inputting / outputting the communication data; a receiving unit for receiving communication data input from the communication data input / output terminal; and And when the communication data is input from the communication data input / output terminal, the communication data transmitted from the terminal device and the other terminal device A collision detecting unit that determines that the transmitted communication data has collided and outputs a collision detection signal to the control unit, wherein the control unit receives the communication data from another terminal device. The communication data is transmitted when not, and when the collision detection signal is input during transmission of the communication data, the transmission of the communication data is interrupted, and the communication data is transmitted again after waiting for a random time. It is characterized by.

According to a second aspect of the present invention, the collision detection unit compares a voltage value of the communication data input from the communication data input / output terminal with a voltage value of a preset reference voltage. Having a comparator, and when the transmitter turns off the output of the transmission signal, and the voltage value of the communication data input from the communication data input / output terminal exceeds the voltage value of the reference voltage In this case, it is determined that the communication data transmitted from the terminal device of the mobile station collides with the communication data transmitted from another terminal device.

According to the communication terminal device of the present invention, it is possible to detect a collision of communication data even in a long transmission line in an air conditioning system network using frequency modulation. Further, since communication such as an acknowledgment (ACK) for transmission data can be made unnecessary, the amount of communication can be reduced.

Further, according to the communication terminal device of the present invention, it is possible to more accurately determine the collision of communication data according to the noise level of the network.

1 is an overall view showing an example of an air conditioner system according to the present invention. It is a block diagram which shows schematic structure of the terminal device which concerns on this invention. It is explanatory drawing explaining the voltage level of the analog signal transmitted from the other terminal device detected near the zero crossing point of a transmission signal. It is a timing chart explaining the collision detection performed with the communication circuit which concerns on this invention. It is a flowchart of the communication process performed in the control part of the terminal device which concerns on this invention. It is a block diagram which shows the conventional communication apparatus. It is explanatory drawing explaining attenuation | damping of the voltage level in a transmission line.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the accompanying drawings. Note that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the spirit of the present invention.

  FIG. 1 is an overall view showing an example of an air conditioner system according to the present invention. FIG. 1 shows a case where the air conditioner system of the present invention is used in a five-story building. The air conditioner system 1 includes a plurality of outdoor units 20 and indoor units 30 connected to a network, and a terminal device of a central management device 10 that controls and manages them. The central management device 10 is connected to the transmission lines L1 to L5, and each terminal device is connected by transmission lines (L1-1 to L1-3,... L5-1 to L5-2) further branched from the transmission lines L1 to L5. The outdoor unit 20 is connected to the outside of the building, and the indoor unit 30 is installed on each floor of the building. The remote controller 31 used by each floor user is connected to each indoor unit 30 via a communication line. However, since the communication destination is limited to the indoor unit connected via the communication line, the remote controller 31 is the terminal of the present invention. Not included in the device. Further, the five-digit alphanumeric characters written on each terminal device indicate the address of each terminal.

Here, assuming that control is performed from the central management apparatus 10 to the indoor unit 30 of the address “5F020” installed on the fifth floor, the communication data transmission path at this time will be described. The communication data transmitted from the central management device 10 is transmitted to the transmission line L1 connected to the communication unit of the central management device 10 (not shown), and is transmitted to the transmission line L5 via the transmission line L2 and L3 and L4 (not shown). Communicated. Then, it further reaches the indoor unit 30 with the address “5F020” via the transmission line L5-2 branched from the transmission line L5, and is received by the receiving unit 90 (to be described later) of the indoor unit 30, and the indoor unit 30 performs communication. Control is performed according to the contents of the data.

  FIG. 2 is a block diagram showing a schematic configuration of the terminal device according to the present invention. In FIG. 2, the terminal device 40 outputs a digital signal obtained by frequency-modulating transmission data and a control unit 50 that outputs a zero-cross discrimination signal during a period in which the digital signal is before and after the zero-cross point, and a transmission connected to the control unit 50. Unit 60, a communication data input / output terminal 70 that is connected to the transmission unit 60 and inputs / outputs communication data between the terminal device 40 and the transmission line, and a transmission unit 60 between the control unit 50 and the communication data input / output terminal 70. Collision detection unit 80 connected in parallel, and further, the control unit 50 and the communication data input / output terminal 70 are connected in parallel with the collision detection unit 80 and receive the communication data transmitted from other terminal devices. Part 90.

  In FIG. 2, a transmission unit 60 is connected to the control unit 50 and converts a digital signal input from the control unit 50 into an analog signal and outputs the analog signal, and a D / A converter 61 connected to the D / A converter 61. An amplifier 62 that amplifies the analog signal input from the A converter 61 to an appropriate level when it is transmitted to the transmission line, and an analog switch 63 that is connected to the amplifier 62 and is turned off when a zero-cross discrimination signal is input from the control unit 50. And an LPF 64 that is a low-pass filter that is connected to the analog switch 63 and that reduces and outputs a high-frequency component of the analog signal input from the analog switch 63. The LPF 64 (low-pass filter) is a noise (high-frequency component) generated when the D / A converter 61 converts transmission data from a digital signal to an analog signal and when the analog signal is turned off in the analog switch 63. ) Is suppressed from being output to the transmission line.

  In FIG. 2, the collision detection unit 80 detects a signal “Hi” when the voltage level of the analog signal input to the communication data input / output terminal 70 is higher than a reference voltage (for example, the maximum noise level value of the received signal). The comparator 81 outputs a “Low” signal when the voltage level of the input signal is lower than the reference voltage, one input terminal is the output of the comparator 81, and the other input terminal is the zero cross discrimination. A control unit connected to the output unit only when both the “Hi” signal from the comparator 81 and the zero cross discrimination signal from the control unit 50 are input simultaneously. And an AND circuit 82 for outputting a collision detection signal indicating occurrence of transmission data collision to 50.

  FIG. 3 is an explanatory diagram illustrating the voltage level of an analog signal transmitted from another terminal device detected near the zero cross point of the transmission signal. FIG. 3A shows the waveform of an analog signal corresponding to the communication data “1010” transmitted from a certain terminal device (the central management device 10, the outdoor unit 20, and the indoor unit 30). FIG. 3B shows a waveform of an analog signal corresponding to communication data “0101” transmitted from another terminal device connected to a position far from the terminal device of FIG. . 3 (3) is received by the terminal device of FIG. 3 (1) when the analog signals of FIG. 3 (1) and FIG. 3 (2) collide on the transmission path near the terminal device of FIG. 3 (1). The waveform of the collision signal is shown.

  From the analog signal waveforms in FIG. 3 (1) and FIG. 3 (3), although the collision signal is disturbed when compared with the waveform of the transmitted signal, a waveform that can be discriminated as a signal indicating the communication data of “1010” is obtained. Since it is maintained, it can be seen that it may not be possible to determine that a collision has occurred by comparing transmitted and received signals.

  On the other hand, FIG. 3 (4) is transmitted from the other terminal apparatus of FIG. 3 (2) that occurs at timings t1 to t6 when the transmission signal of FIG. 3 (1) reaches the zero cross point (that is, the voltage of the transmission signal is 0V). The potential difference (voltage level) with the signal of the communication data is shown. In the example of FIG. 3, a signal transmitted / received by a certain terminal device has a positive potential difference with reference to 0V at t1 to t3 when the transmission signal becomes a zero cross point, and a negative value with reference to 0V at t4 to t6. It can be seen that a potential difference has occurred.

  That is, in FIG. 3, even when it is not possible to determine the collision by comparing the transmitted and received communication data, at the zero cross point where the voltage of the transmission signal is 0 V, only the communication data transmitted from other terminal devices is the communication data. Since it is input to the input / output terminal 70, the presence / absence of transmission of communication data from other terminal devices by checking the voltage value of the signal input to the communication data input / output terminal 70 at the zero cross point of the transmission signal, that is, It shows that a signal collision can be determined.

  FIG. 4 is a timing chart for explaining collision detection performed by the terminal device according to the present invention. FIG. 4A shows the waveform of an analog signal output from the amplifier 62 when the terminal device transmits communication data. FIG. 4 (4) shows the waveform of an analog signal transmitted from another terminal device at the same time that the terminal device attempts to transmit the communication data of FIG. 4 (1). FIG. 4 explains how a collision of signals is detected in the terminal device 40 when these two analog signals are transmitted to the transmission path.

4 (2) shows the timing at which the switch is turned off when a zero-cross discrimination signal indicating before and after the zero-cross point is input from the control unit 50 to the analog switch 63 while the terminal device 40 is transmitting communication data. Show. By the switching of OFF-1 to OFF-5 shown in FIG. 4 (2), the analog signal that has passed through the analog switch 63 has a waveform shown in FIG. 4 (3). Note that an analog signal partially cut by the analog switch 63 before and after the zero crossing point is determined as “0” or “1” depending on the density of the analog signal at the receiving unit of the terminal device that has received the analog signal. To demodulate to data,
Even if the analog signal is temporarily cut before and after the zero-cross point, it is possible to determine the density state, and it does not affect the demodulation of the communication data.

  FIG. 4 (5-1) shows the waveform when the analog signals shown in FIGS. 4 (3) and 4 (4) input to the communication data input / output terminal 70 collide with each other. The reference voltage used for the determination is shown by a one-dot chain line. Note that the comparator 81 is configured to be able to perform a signal collision determination based on both a positive value and a negative value of the voltage level indicated by the input analog signal.

FIG. 4 (5-2) shows a signal output from the comparator 81. The comparator 81 outputs a “Hi” signal when the voltage value of the input signal shown in FIG. 4 (5-1) is higher than the positive or negative value of the reference voltage used for collision determination. When the voltage value is lower than the positive and negative values of the reference voltage, a “Low” signal is output. That is, it is determined that the analog switch timings OFF-1 to OFF-3 are higher than the positive value of the reference voltage, and OFF-4 to OFF-5 are determined to be higher than the negative value of the reference voltage. A “Hi” signal is output.

  FIG. 4 (5-3) shows the collision detection signal output from the AND circuit 82. The AND circuit 82 receives the collision detection signal to the control unit 50 when both the “Hi” signal input from the comparator 81 and the zero-cross determination signal indicating before and after the zero-cross point input from the control unit 50 are input. Is output. The terminal device 40 can detect a collision of transmission signals during transmission of communication data by such a configuration and operation.

  FIG. 5 is a flowchart of communication processing performed by the control unit of the terminal device according to the present invention. Note that ST described in the flowchart of FIG. 5 represents a step, and the number following this represents a step number.

  The control part 50 of the terminal device 40 confirms whether the receiving part 90 received communication data (ST1). When the receiving unit 90 has not received communication data (ST1-No), it is confirmed whether or not transmission-scheduled data that is communication data transmitted from the terminal device 40 is present in the buffer (ST2). If there is no data to be transmitted (ST2-No), it is confirmed whether or not a request to stop transmission / reception (for example, operation stop operation from the remote controller 31) has been received (ST3). If a request to stop transmission / reception is accepted (ST3-Yes), the communication process is terminated. Moreover, when the request | requirement of transmission / reception stop is not received (ST3-No), it returns to ST1.

  When the communication data is received from the receiving unit 90 in ST1 (ST1-Yes), the control unit 50 of the terminal device 40 checks whether the received communication data is data addressed to its own address (ST4). If the received data is addressed to its own address (ST4-Yes), control is performed according to the content of the received data (ST5). Then, the process returns to ST1. If the received data is not addressed to its own address (ST4-No), the received data is discarded (ST6). Then, the process returns to ST1.

  In ST2, when there is scheduled transmission data (ST2-Yes), the control unit 50 of the terminal device 40 confirms whether a data transmission standby timer, which will be described later, is in operation (ST7). If the data transmission standby timer is not in operation (ST7-No), transmission of the scheduled transmission data is started (ST8). Next, it is confirmed whether or not the data transmission is completed (ST9). If the data transmission is not completed (ST9-No), it is confirmed whether or not a collision detection signal is input from the AND circuit 82 (ST10). When a collision detection signal is input from the AND circuit 82 (ST10-Yes), the transmission of data is interrupted and the transmission data is stored in a buffer, and a random time (for example, a random number is stored inside the control unit 50) at each interruption. A standby timer for data transmission is operated inside the control unit 50 so as to wait until a time based on the value obtained and generated (ST11). Then, the process returns to ST1.

  In ST7, when the data transmission standby timer is operating (ST7-Yes), and in ST9, when the data transmission is completed (ST9-Yes), the control unit 50 of the terminal device 40 goes to ST3. Jump. In ST10, if no collision detection signal is input from the AND circuit 82 (ST10-No), the process jumps to ST9.

DESCRIPTION OF SYMBOLS 1 Air conditioner system 10 Central management apparatus 20 Outdoor unit 30 Indoor unit 31 Remote control 40 Terminal device (10 central management apparatus, 20 outdoor unit, 30 indoor unit)
50 Control Unit 60 Transmitting Unit 61 D / A Converter 62 Amplifier 63 Analog Switch 64 LPF (Low Pass Filter)
70 Communication Data Input / Output Terminal 80 Collision Detection Unit 81 Comparator 82 AND Circuit 90 Reception Unit

Claims (2)

In a terminal device that performs communication using a frequency modulation method, the control unit controls transmission / reception of communication data, and outputs a zero-cross determination signal indicating a period during which the waveform of the transmission signal is around the zero-cross point during transmission of the communication data; A transmission unit that turns off the output of the transmission signal in response to a zero-cross determination signal; a communication data input / output terminal that connects the terminal device and the transmission line and inputs / outputs the communication data; and the communication data input / output terminal A receiving unit that receives communication data input from the communication unit, and when the transmission unit turns off the output of the transmission signal during transmission of the communication data, and the communication data is input from the communication data input / output terminal. When it is determined that the communication data transmitted from its own terminal device has collided with the communication data transmitted from another terminal device, a collision detection signal is transmitted to the control unit. A collision detection unit that outputs a signal, and the control unit transmits the communication data when the reception unit is not receiving the communication data from another terminal device, and the collision occurs during transmission of the communication data. When a detection signal is input, the transmission of the communication data is interrupted, and after waiting for a random time, the communication data is transmitted again. The collision detection unit includes a comparator that compares a voltage value of the communication data input from the communication data input / output terminal with a voltage value of a preset reference voltage, and the transmission unit When the output is turned off, and when the voltage value of the communication data input from the communication data input / output terminal exceeds the voltage value of the reference voltage, the communication data transmitted from the terminal device of its own The terminal device according to claim 1, wherein it is determined that the communication data transmitted from another terminal device has collided.

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