JP2010103603A - Transmission control apparatus and transmission control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission control apparatus and a transmission control method which, when communication errors are generated during communication, and restores synchronization between apparatuses to perform communication. <P>SOLUTION: The transmission control apparatus 60 includes: an error detecting part 621 for detecting whether a communication error is generated during communication; a monitoring part 622 which, when the generation of the communication error is detected by the error detection part 621, monitors whether a signal change is generated in a monitoring period, after a start bit until it is confirmed that there is no signal change on a transmission line 100; and a control part 623 which, when no signal change is confirmed by the monitoring part 622, starts a suspended period from the end of the start bit, after the confirmed monitoring period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transmission control apparatus and a transmission control method for performing communication in an asynchronous manner that synchronizes each data.

The home bus system generally employs an asynchronous method in which serial data is transferred. Serial data transfer is a method in which parallel data is sequentially transmitted in 1-bit units. In the start-stop synchronization method, a start bit indicating the start of serial data is attached to the head of the data, and a stop indicating the end of serial data. A bit is appended to the end of the data. Such a technique is disclosed in the following documents, for example.
JP 2004-356935 A

  However, in the method disclosed in Patent Document 1, when a communication error occurs during communication, the timing for starting a pause period necessary for synchronization is shifted, and communication between a plurality of devices is not recovered. May not be able to be performed.

  Therefore, when a communication error occurs during communication, it is desired to restore communication between a plurality of devices so that communication can be performed.

  The present invention has been made under the above circumstances, and it is an object of the present invention to provide a transmission control device and a transmission control method for performing communication by restoring synchronization between devices when a communication error occurs during communication. To do.

  A transmission control apparatus according to a first aspect of the present invention is a transmission control apparatus that sequentially transmits and receives a plurality of data including a start bit at the head via a transmission line, and includes an error detection unit, a monitoring unit, and a control unit. Yes. The error detection unit detects whether a communication error has occurred during communication. When the error detection unit detects the occurrence of a communication error, the monitoring unit outputs a signal in each monitoring period after a plurality of start bits including the first start bit until it is confirmed that there is no signal change on the transmission line. Monitor for changes. When it is confirmed by the monitoring unit that there is no signal change, the control unit starts a pause period in which the transmission line is in a no-signal state from the end of the start bit after the confirmed monitoring period.

  In this transmission control apparatus, when a communication error occurs during communication, the timing for starting the suspension period is controlled based on the presence or absence of a signal change within the monitoring period. As a result, the pause period is started without any deviation in the timing of starting the pause period. Therefore, the communication between the transmission control devices can be restored and communication can be performed.

  The transmission control device according to the second invention is the transmission control device according to the first invention, and when the monitoring unit confirms that there is no signal change in the monitoring period after the first start bit, the control unit The pause period may be started from the end of the second start bit next to the start bit.

  As a result, the suspension period starts from the end of the second start bit. Therefore, the communication between the transmission control devices can be restored and communication can be performed.

  The transmission control device according to a third aspect of the present invention is the transmission control device of the first or second aspect, further comprising a noise detection unit that detects whether noise has occurred during the pause period. Good. In that case, when the generation of noise is detected by the noise detection unit, the monitoring unit further regards the noise signal as a start bit and monitors whether there is a signal change in each monitoring period after the start bit. You may do it.

  Thereby, in this transmission control apparatus, even when noise occurs during the pause period, the timing for starting the pause period can be controlled based on the presence or absence of a signal change within the monitoring period. Therefore, the communication between the transmission control devices can be restored and communication can be performed.

  A transmission control device according to a fourth invention is the transmission control device according to the first invention, wherein an outdoor unit of the air conditioner and the indoor unit are connected to the transmission path, and the error detection unit is connected to the outdoor unit of the air conditioner. You may make it detect whether the communication error generate | occur | produced during communication for signal transmission between indoor units.

  Thereby, this transmission control apparatus is applicable to the system provided with the outdoor unit and indoor unit of an air conditioner.

  A transmission control method according to a fifth aspect of the present invention is a transmission control method for transmitting / receiving a plurality of data including a start bit at the head via a transmission path in order, and includes the following steps. In other words, the transmission control method includes a step of detecting whether or not a communication error has occurred during communication, and, if the occurrence of a communication error is detected, until the confirmation that there is no signal change on the transmission path. A step of monitoring whether or not there is a signal change in each monitoring period after a plurality of start bits including one start bit; and if it is confirmed that there is no signal change, the start bit after the confirmed monitoring period And a step of starting a pause period in which no signal is transmitted on the transmission line from the end.

  In this transmission control method, when a communication error occurs during communication, the timing for starting the pause period is controlled based on the presence or absence of a signal change within the monitoring period. As a result, the pause period is started without any deviation in the timing of starting the pause period. Therefore, communication can be performed with synchronization recovery.

  In the transmission control apparatus according to the first aspect of the present invention, when a communication error occurs during communication, communication can be performed while recovering the synchronization between the transmission control apparatuses.

  In the transmission control apparatus according to the second aspect of the invention, communication can be performed while recovering the synchronization between the transmission control apparatuses.

  In the transmission control apparatus according to the third aspect of the invention, communication can be performed while recovering the synchronization between the transmission control apparatuses even when noise occurs during the idle period.

  The transmission control device according to the fourth invention can be applied to a system including an outdoor unit and an indoor unit of an air conditioner.

  In the transmission control method according to the fifth aspect of the present invention, when a communication error occurs during communication, communication can be performed with recovery of synchronization.

Embodiment FIG. 1 is a diagram illustrating a configuration example of an entire system including a transmission control apparatus according to an embodiment of the present invention.

  In the air conditioner system 1 of FIG. 1, a plurality of outdoor units 10, 20, 30 and a plurality of indoor units 11-14, 21-24, 31-34 are arranged on a transmission path 100 (bus). As the transmission line 100, for example, a twisted pair line is used.

  Each outdoor unit 10, 20, 30 is communicably connected to the management controller 40 via the transmission line 100, and the management controller 40 is communicably connected to the monitoring device 50 via the control line 200. . In this embodiment, a panel-type controller that can be connected to the monitoring device 50 will be described as an example of the management controller 40.

  The management controller 40 includes a microcomputer, a display device, an operation button, and a transmission control device 60 described later, and is configured to control the operation of each indoor unit. The types of operation control include indoor unit individual control, zone control, collective operation, temperature control, and the like.

  The monitoring device 50 includes a CPU, a memory, a display, and an input device such as a keyboard, and is configured to monitor the operation status of the entire air conditioner system 1. For example, on the display of the monitoring device 50, the operation status and operation mode of each indoor unit are displayed. Moreover, in the monitoring apparatus 50, switching of the operation condition of each indoor unit, an operation mode, etc. can be controlled. In the example of FIG. 1, a personal computer is described as the monitoring device 50, but a computer such as a server computer may be applied.

  Each of the outdoor units 10, 20, 30 and each of the indoor units 11-14, 21-24, 31-34 is a so-called multi-air conditioner for buildings, and has a transmission control device 60. In this embodiment, the transmission control device 60 is incorporated in each outdoor unit and each indoor unit, but may be configured separately. Further, although the transmission control device 60 performs communication in accordance with BACnet (registered trademark), which is a communication protocol standard for building networks, other communication protocol standards may be applied. BACnet (registered trademark) is an abbreviation for Building Automation and Control Networking protocol.

[Configuration of transmission control device]
Next, the configuration of the transmission control device 60 will be described. Although another transmission control device 60a is shown in FIG. 2, the configuration of this transmission control device 60a is the same as that of the transmission control device 60.

  FIG. 2 is a diagram illustrating a configuration example of the transmission control apparatus. The transmission control device 60 of FIG. 2 includes a communication driver 61, a protocol controller 62 (hereinafter referred to as controller 62), and a CPU (Central Processing Unit) 63.

  The CPU 63 is connected to the controller 62 and is configured to control the operation of the entire transmission control device 60.

  The controller 62 generates data necessary for realizing communication with the other transmission control device 60a. In this embodiment, as the control method, for example, a CSMA / CD (Carrier Sense Multiple Access with Collision Detection) winning method is adopted, and as the synchronization method, for example, start-stop synchronization is adopted. For this reason, in the example of FIG. 3, the generated data (character) has an 11-bit configuration corresponding to the control method and the synchronization method described above. That is, one data is composed of a total of 11 bits including a 1-bit start bit ST, 8-bit transfer data D0 to D7, 1-bit parity P, and 1-bit stop bit SP.

  The start bit ST is a bit indicating the start of data transmission, and the stop bit SP is a bit indicating a data delimiter. The stop bit SP is used in pairs with the start bit ST.

  Returning to FIG. 2, the controller 62 will be described in detail.

  The controller 62 includes an error detection unit 621, a monitoring unit 622, a control unit 623, a noise detection unit 624, and a sending unit 625. Each of these units 621 to 625 is composed of circuits such as a register and a buffer. These functions will be described below.

  The sending unit 625 sends data including the start bit ST. In that case, the transmission unit 625 outputs a transmission data signal generated based on the bits in the data to the communication driver 61. In the example of FIG. 3, the start bit ST is added to the head of the data. For this reason, the sending unit 625 first outputs a send data signal of logic 0 (−) to the communication driver 61 in synchronization with the start bit ST. Further, the sending unit 625 outputs a sending data signal of logic 1 (+) or logic 0 (−) to the communication driver 61 in synchronization with other bits (transfer data or the like).

  The error detection unit 621 detects whether or not a communication error has occurred during communication with another transmission control device 60a. In this embodiment, the error detection unit 621 determines whether or not a communication error has occurred based on the received data signal from the communication driver 61.

  The reception data signal is generated based on the data on the transmission line 100 taken in by the communication device 61. The waveform of the received data signal to be generated corresponds to the waveform of data on the transmission line 100. For example, if the data on the transmission line 100 is (−), the received data signal is L (“0”), and if the data on the transmission line 100 is (+), the received data signal is H (“1”). )).

  Here, the communication error includes a bus error and a reception data error. A bus error is a logic level mismatch occurring between a transmission data signal and a reception data signal. The reception data error means that the start bit is not detected when the start bit can be received.

  In this embodiment, on the transmission line 100, the logic 0 data has a higher priority than the logic 1 data. Therefore, when the error detection unit 621 receives logic 1 data from the communication driver 61 even though the sending unit 625 outputs logic 0 data, a logic level mismatch has occurred and a bus error has occurred. It becomes. For example, when the error detection unit 621 receives a logic 1 signal from the communication driver 61 even though the transmission unit 625 outputs a start bit, a bus error occurs.

  In this embodiment, when the transmission control device 60 performs only reception without transmitting data (communication packet), the error detection unit 621 detects a start bit at a specified timing. . If the error detection unit 621 does not detect the start bit at that time, a reception data error occurs.

  When detecting a communication error, the error detection unit 621 sets an error flag (not shown) to, for example, “1”. Then, the error detection unit 621 notifies the CPU 63 of the error indicated by the error flag “1”, and generates an interrupt to the CPU 63.

  When the error flag becomes “1”, the error detection unit 621 receives the next reception data signal (next data fetched from the transmission line 100), thereby clearing the cause of the communication error and detecting the error. The unit 621 sets the error flag to an initial value (0).

  When the error detection unit 621 detects the occurrence of a communication error, the monitoring unit 622 monitors whether there is a signal change until it is confirmed that there is no signal change on the transmission line 100 within the monitoring period. .

  The monitoring period is a period for monitoring the presence or absence of a signal change on the transmission line 100 (bus monitoring). As the monitoring period, for example, a time corresponding to 10 bits (a total time corresponding to 10 bits of the transfer data D0 to D7, the parity P, and the stop bit SP) is set.

  Monitoring of the monitoring period by the monitoring unit 622 is continued until the monitoring unit 622 no longer confirms a signal change. In that case, the monitoring periods are sequentially set. For example, when a bus error is detected, the monitoring period is first a period from the end of the first start bit (first start bit) after detection to the start of the next start bit (second start bit). If the monitoring unit 622 confirms a signal change within this period, the next monitoring period is a period from the end of the second start bit to the start of the next start bit.

  When a received data error is detected, the monitoring period is first a period from the end of the start bit (first start bit) that should be detected to the start of the next start bit (second start bit). If the monitoring unit 622 confirms a signal change within this period, the next monitoring period is a period from the end of the second start bit to the start of the next start bit.

  When the monitoring unit 622 confirms that there is no signal change, the control unit 623 starts the suspension period from the end of the start bit after the confirmed monitoring period. The idle period is a period for setting the transmission line 100 on a no-signal state.

  During the suspension period when a communication error is detected, the control unit 623 changes a state counter (MDR) (not shown) from “0” to “2”. When the status counter (MDR) is “0”, the control unit 623 detects that the bus is empty (status S0). When the state counter is “2”, the control unit 623 waits for data input (state S2).

  The relationship between the state counter (MDR) and the state is determined in advance according to the provisions of BACnet (registered trademark). The controller 623 performs a predetermined process based on the value of the state counter (MDR).

  The noise detection unit 624 detects whether noise has occurred during the pause period. In this embodiment, the noise detection unit 624 determines whether noise has occurred based on the received data signal from the communication driver 61.

  When the noise detection unit 624 receives a reception data signal having a pulse width in spite of the pause period, the generation of noise is confirmed. In that case, the monitoring unit 622 regards the noise signal as a start bit, and monitors whether there is a signal change in the monitoring period after the start bit.

  If the noise signal is regarded as a start bit, the transmission unit 625 outputs a transmission data signal of logic 0 (−) to the communication driver 61 in synchronization with the noise signal.

  The communication driver 61 has an input terminal IN and an output terminal OUT, and is configured to send data onto the transmission line 100 and to input data on the transmission line 100.

  At the time of data transmission, the communication driver 61 transmits data (communication packet) based on the transmission data signal from the transmission unit 621 from the output terminal OUT.

  When inputting data, the communication driver 61 inputs data (communication packet) on the transmission line 100 from the input terminal IN.

[Relationship between communication packet and pause period]
FIG. 4 is an explanatory diagram showing the relationship between communication packets and idle periods.

  The communication packet is transmitted after the pause period T20 ends. This is for synchronizing communication packets.

  During the suspension period T20, noise determination is performed by the noise detection unit 624, and when the communication packet is transmitted on the transmission line 100 after the suspension period T20 ends, a communication error determination is performed by the error detection unit 621.

[Synchronous recovery operation when noise is detected]
FIG. 5 is an explanatory diagram showing the synchronization recovery operation when noise is detected.

  In the example of FIG. 5A, the case where noise is not detected in the pause period T20 is shown, so that the communication packet is transmitted after the pause period T20. In this case, the control unit 623 controls the suspension period T20 by changing a state counter (MDR) (not shown) from “0 (state S0)” to “1 (state S1)”. In the state S1, there is no signal on the transmission line 100.

  On the other hand, in the example of FIG. 5B, the pause period starts at the same timing as the pause period T20 of FIG. 5A, but noise is detected and the pause period T20 is the end of the noise signal (predetermined time t). start from.

[Normal synchronization recovery operation when a communication error is detected]
FIG. 6 is an explanatory diagram showing a normal synchronization recovery operation including when a communication error is detected.

  In the example of FIG. 6A, a case where a communication error is not detected is shown, so that the communication packet is transmitted after the suspension period T20.

  On the other hand, in the example of FIG. 6B, the communication packet is transmitted at the same timing as the transmission of the communication packet of FIG. 6A. However, a communication error is detected, and the pause period T20 indicates that the communication error is Started after occurrence.

  The example of FIG. 6C also shows a case where a communication error is detected, but the suspension period T20 is not started immediately after the occurrence of the communication error (FIG. 6B), but other devices It starts after the data reception from the (transmission control device) is completed. When a communication error occurs, it is common to prevent other devices from sending data, but the communication environment (such as a long transmission line distance, many transmission line branches, or a large number of devices) Depending on the situation, data can be transmitted even after a communication error occurs.

  Therefore, the suspension period T20 shown in the example of FIG. 6B does not coincide with the start timing of the suspension period T20 shown in the examples of FIGS. 6A and 6C, and communication packets from each device are transmitted. Collisions on the road 100 may occur. This state will be described with reference to an example shown in FIG.

  In the example of FIG. 7, three devices (transmission control devices) A, B, and C are shown. In the example of the device A in FIG. 7A, the communication period does not occur, and the suspension period T20 starts from the end of the communication packet and shifts from the state S0 to the state S1 (MDR = 0 → 1).

  In the example of the apparatus B in FIG. 7B, a communication error is detected, and the suspension period T20 starts immediately after the occurrence of the communication error. In this case, the suspension period T20 shifts from the state S0 to the state S2 (MDR = 0 → 2).

  In the example of the device C in FIG. 7C, no communication error is detected, and the suspension period T20 starts at the same timing as the timing shown in the example in FIG. In that case, the suspension period T20 shifts from the state S0 to the state S1 (MDR = 0 → 1).

  Then, the start timing of the suspension period T20 does not match between the devices A, B, and C. Further, in the two apparatuses A and C, the suspension period T20 shifts from the state S0 to the state S1 (no signal state), and therefore cannot synchronize with the communication packet from the apparatus B in the state S1. Accordingly, communication packets from the devices A, B, and C collide on the transmission line 100.

  Therefore, in the transmission control device 60 of this embodiment, when a communication error is detected, control is performed so that the timings at which the suspension period T20 starts are matched. The operation in that case will be described below.

[Synchronous recovery operation when a communication error is detected in this embodiment]
FIG. 8 is an explanatory diagram showing a synchronization recovery operation when a received data error is detected in this embodiment. In FIG. 8, description will be made assuming that the transmission control device 60 performs only reception without transmitting data (communication packet).

  In the example of FIG. 8, the start bit (first start bit) to be detected at a specified timing is shown, but the error detection unit 621 cannot detect the start bit and detects the occurrence of a reception data error. Is done. In this case, the monitoring period T10 starts from the end of the start bit (first start bit) that should be detected originally.

  When no signal change is confirmed within the monitoring period T10, the pause period T20 starts from the end of the second start bit (FIG. 8A). On the other hand, when the signal change is confirmed, the monitoring period T10 continues from the end of the second start bit (FIG. 8B).

  FIG. 9 is an explanatory diagram showing a synchronization recovery operation when a bus error is detected in the present embodiment.

  In the example of FIG. 9, the error detection unit 621 detects the occurrence of a bus error after the start bit. In this case, the monitoring period T10 starts from the end of the first start bit (first start bit) after detection.

  When no signal change is confirmed within the monitoring period T10, the pause period T20 starts from the end of the second start bit (FIG. 9A). On the other hand, when the signal change is confirmed, the monitoring period T10 continues from the end of the second start bit (FIG. 9B).

[Synchronous recovery operation when noise is detected in this embodiment]
FIG. 10 is an explanatory diagram showing a synchronization recovery operation at the time of noise detection in the present embodiment.

  Since the example of FIG. 10 shows a case where noise occurs during the pause period, the noise detection unit 624 detects noise. In that case, since the monitoring unit 622 regards the noise as a start bit, the monitoring period T10 starts from the end of the noise signal.

  When no signal change is confirmed within the monitoring period T10, the pause period T20 starts from the end of the next start bit (FIG. 10A). On the other hand, when the signal change is confirmed, the monitoring period T10 continues from the end of the next start bit (FIG. 10B).

  FIG. 11 is a flowchart showing the synchronization recovery operation in the present embodiment.

  First, the transmission control device 60 (control unit 623) starts a suspension period T20 (step S11). In this embodiment, the control unit 623 starts the suspension period T20 based on the value of the state counter (MDR).

  In the suspension period T20, the transmission control device 60 (noise detection unit 624) detects the presence or absence of noise (step S12). In this embodiment, the noise detection unit 624 receives a reception data signal generated based on data on the transmission line 100 from the communication driver 61, and determines whether noise has occurred based on the pulse width of the reception data signal. To do.

  If no noise is detected (No in step S12), the transmission control device 60 (control unit 623) determines whether or not the suspension period T20 has ended (step S13), and if it has not ended (No in step S13). ), The process returns to step S12. On the other hand, if completed (Yes in step S13), the process proceeds to step S21.

  Returning to step S12, description will be given. When noise is detected (Yes in step S12), the transmission control device 60 (monitoring unit 622) monitors a signal change during the monitoring period T10 (step S14). In that case, to explain with the example shown in FIG. 10, the monitoring period T10 starts from the end of the noise signal. Then, the transmission control device 60 (monitoring unit 622) determines whether or not there is a signal change (step S15). In this embodiment, the monitoring unit 622 receives a reception data signal generated based on the data (communication packet) on the transmission line 100 from the communication driver 61, and changes the signal based on the pulse width of the reception data signal. Monitor.

  As a result, if there is a signal change (Yes in step S15), the process returns to step S14, and the transmission control device 60 (monitoring unit 622) continuously monitors the signal change in the monitoring period T10. In that case, taking the case shown in FIG. 10B as an example, the monitoring period T10 starts from the end of the next start bit. On the other hand, if there is no signal change (No in step S15), the process returns to step S11, and the transmission control device 60 (control unit 623) starts the suspension period T20. In that case, taking the case shown in FIG. 10A as an example, the pause period T20 starts from the end of the next start bit.

  In step S21, the transmission control device 60 starts communication with another transmission control device 60a (step S21). In this case, for example, the sending unit 625 outputs a sending data signal generated in response to a sending request (command) from the CPU 63 to the communication device 61. In the communication device 61 that has received the transmission data signal, data (communication packet) generated based on the transmission data signal is transmitted to the transmission line 100 from the output terminal OUT.

  In this case, as described with reference to the example shown in FIG. 3, since the start bit ST is added to the head of data, data including the start bit ST at the head is transmitted on the transmission path 100.

  Next, the transmission control device 60 (error detection unit 621) determines whether or not the start bit ST is detected (step S22). In this embodiment, the error detection unit 621 receives a reception data signal generated based on the data on the transmission line 100 from the communication driver 61, and determines whether the start bit ST is present based on the pulse width of the reception data signal. Detect. The error detection unit 621 detects the start bit ST if there is a received data signal having a predetermined pulse width at a predetermined time.

  As a result, if the start bit ST is not detected (No in step S22), the process proceeds to step S14 described above. For example, in the case where the transmission control device 60 is only receiving data without transmitting data (communication packet), when the error detection unit 621 does not detect the start bit ST at a specified timing (No in step S22), A reception data error occurs, and the process proceeds to step S14. In step S14, the transmission control device 60 (monitoring unit 622) monitors signal changes during the monitoring period T10. In that case, the case shown in FIG. 8 will be described as an example. The monitoring period T10 starts from the end of the first start bit (start bit that should be detected originally).

  On the other hand, if the start bit ST is detected (Yes in step S22), the transmission control device 60 (error detection unit 621) performs a predetermined period (in this embodiment, for example, after the end of the detected start bit ST). It is determined whether or not there is a bus error during a period until the start bit ST of (step S23). The error detection unit 621 determines that there is a bus error when the transmission unit 625 receives the logic 1 reception data signal from the communication driver 61 even though the transmission unit 625 outputs the logic 0 start bit ST.

  As a result of the determination described above, if there is no bus error (No in step S23), the process proceeds to step S24, and the transmission control device 60 (error detection unit 621) determines whether the communication is completed (step S24). If the communication has not ended (No in step S24), the process returns to step S23. If the communication has ended (Yes in step S24), the process proceeds to step S11 for starting the suspension period T20. In that case, taking the case shown in FIG. 8A as an example, the pause period T20 starts from the end of the second start bit.

  On the other hand, if there is a bus error (Yes in step S23), the transmission control device 60 (monitoring unit 622) continuously monitors the signal change in the next monitoring period T10. In that case, taking the case shown in FIG. 9B as an example, the monitoring period T10 starts from the end of the second start bit.

  When a communication error (bus error and reception data error) is detected, the error detection unit 621 notifies the CPU 63 of the error indicated by the error flag “1” and generates an interrupt to the CPU 63.

  When the error flag becomes “1”, the error detection unit 621 receives the next reception data signal (next data fetched from the transmission line 100), thereby clearing the cause of the communication error and detecting the error. The unit 621 sets the error flag to an initial value (0).

  Thus, according to this embodiment, in the transmission control device 60, the monitoring unit 622 confirms that there is no signal change on the transmission line 100 when the error detection unit 621 detects the occurrence of a communication error. Until then, it is monitored whether there is a signal change in the monitoring period T10. When the monitoring unit 622 confirms that there is no signal change, the control unit 623 starts the suspension period T20 from the end of the start bit after the monitoring period T10.

  Therefore, when a communication error occurs during communication, the timing for starting the suspension period T20 can be controlled based on the presence or absence of a signal change within the monitoring period T10. Thereby, the rest period T20 is started from the end of any start bit. Therefore, the communication between the transmission control devices can be restored and communication can be performed.

<Other embodiments>
The embodiment of the present invention has been described above. However, the hardware configuration and processing order in practice may be changed without departing from the spirit of the present invention.

  The present invention is useful as a transmission control device that performs data communication in an air conditioner system or the like.

It is a figure which shows the structural example of the whole system containing the transmission control apparatus in embodiment of this invention. It is a figure which shows the structural example of the transmission control apparatus of FIG. It is a figure which shows the structural example of the data in embodiment of this invention. It is explanatory drawing which shows the relationship between a communication packet and a dormant period. It is explanatory drawing which shows the synchronous recovery operation | movement at the time of noise detection. It is explanatory drawing which shows the normal synchronous recovery operation | movement including the time of the detection of a communication error. It is explanatory drawing which shows the state which a communication packet collides on a transmission line. It is explanatory drawing which shows the synchronous recovery operation | movement at the time of the reception data error detection in this embodiment. It is explanatory drawing which shows the synchronous recovery operation | movement at the time of the bus error detection in this embodiment. It is explanatory drawing which shows the synchronous recovery operation | movement at the time of the noise detection in this embodiment. It is a flowchart which shows the synchronous recovery operation | movement in this embodiment.

Explanation of symbols

10, 20, 30 Outdoor unit 11-14, 21-24, 31-34 Indoor unit 60 Transmission control device 61 Communication device 62 Protocol controller 63 CPU
621 Error detection part 622 Monitoring part 623 Control part 624 Noise detection part 625 Sending part T10 Monitoring period T20 Rest period

Claims (5)

A transmission control device (60) for sequentially transmitting and receiving a plurality of data including a start bit at the head via a transmission line (100),
An error detection unit (621) for detecting whether a communication error has occurred during communication;
When the occurrence of a communication error is detected by the error detection unit, until it is confirmed that there is no signal change on the transmission path, in each monitoring period (T10) after a plurality of start bits including the first start bit, A monitoring unit (622) that monitors whether there is a signal change;
When it is confirmed by the monitoring unit that there is no signal change, the control unit (623) starts a pause period (T20) in which the transmission line is in a no-signal state from the end of the start bit after the confirmed monitoring period. )When,
A transmission control device. When the monitoring unit (622) confirms that there is no signal change in the monitoring period (T10) after the first start bit,
The controller (623) starts the pause period (T20) from the end of the second start bit next to the first start bit.
The transmission control apparatus according to claim 1. A noise detector (624) for detecting whether noise has occurred during the pause period,
When the generation of noise is detected by the noise detection unit, the monitoring unit (622) further regards the noise signal as a start bit, and there is a signal change in each monitoring period (T10) after the start bit. Monitoring whether or not
The transmission control device according to claim 1 or 2. Outdoor units (10, 20, 30) and indoor units (11-14, 21-24, 31-34) of air conditioners are connected to the transmission path (100),
The error detection unit (621) detects whether a communication error has occurred during communication for signal transmission between the outdoor unit and the indoor unit of the air conditioner,
The transmission control apparatus according to claim 1. A transmission control method for transmitting and receiving a plurality of data including a start bit at the beginning via a transmission path in order,
Detecting whether a communication error has occurred during communication (S23);
When the occurrence of the communication error is detected (YES in S23), until it is confirmed that there is no signal change on the transmission path (S26), in each monitoring period after a plurality of start bits including the first start bit. Monitoring whether there is a signal change (S25);
When it is confirmed that there is no signal change (NO in S26), a step (S11) of starting a pause period in which the transmission line is in a no-signal state from the end of the start bit after the confirmed monitoring period; ,
A transmission control method comprising:

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