Communication system

Abstract

To provide a communication system capable of specifying which of a first communication circuit, a second communication circuit, or an electric wire is abnormal when communication cannot be performed between a first device and a second device.SOLUTION: A hot water supply system 10 includes: a first switch unit 161 disposed between a first power line L11 and a first communication line L12; a second switch unit 241 disposed between a second power line L21 and a second communication line L22; a third switch unit 162 disposed on the first power line L11, and communication abnormality diagnosing units 140 and 220. When periodic communication cannot be normally performed, the communication abnormality diagnosis units 140 and 220 switch the first switch unit 161, the second switch unit 241, and the third switch unit 162 to a state different from that when the periodic communication is normally performed, thereby diagnosing which of an electrical wire 500, a first communication circuit 150, or a second communication circuit 230 has an abnormality.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a communication system capable of wired communication.

Background Art

[0002] Conventionally, in a hybrid water supply system, exchange of control signals and data signals by wired communication has been performed between a hot water storage unit having a hot water storage tank and a heat pump unit having a heat pump mechanism. The hot water storage unit and the heat pump unit are each provided with a communication circuit, and these communication circuits are connected by an electrical wiring for communication.

[0003] In addition to the hybrid water supply system, there are various communication systems including two units (devices) that are connected to each other so as to enable wired communication.

[0004] In such a communication system, when communication between the two units becomes impossible, an error state occurs and an error notification is given. However, at this stage, it is impossible to determine which of the communication circuit of the hot water storage unit, the communication circuit of the heat pump unit, and the electrical wiring has an abnormality. Therefore, an operator such as a serviceman has to go to the installation location of the communication system once to check the abnormal location, and then go to the installation location again to perform repairs such as replacing parts, which was time-consuming.

[0005] Patent Document 1 below describes a configuration that enables determination of whether an abnormal location is in the indoor unit or the indoor unit in an air conditioner control device.

[0006] In this air conditioner control device, the indoor unit includes an indoor communication control unit having an indoor communication output unit and an indoor communication input unit, an indoor communication circuit, a first communication abnormality determination unit, and a second communication abnormality determination unit, and the outdoor unit includes an outdoor communication control unit having an outdoor communication output unit and an outdoor communication input unit and an outdoor communication circuit. The indoor communication circuit and the outdoor communication circuit are connected by a connection line and a power line.

[0007] In this air conditioner control device, when the operation control signal input from the outdoor communication output unit to the indoor communication input unit is different from the normal operation control signal, it is determined that a communication abnormality has occurred. In this case, a determination signal is output from the indoor communication output unit to the outdoor communication control unit, and the determination signal is directly returned from the outdoor communication output unit through the indoor communication input unit to the second communication abnormality determination unit and compared with the determination signal directly input from the indoor communication output unit to the second communication abnormality determination unit. When the signals are the same, it is determined that a communication abnormality has occurred in the outdoor unit.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in the above air conditioner control device, when the signals are different and it is not determined that there is a communication abnormality in the outdoor unit, the operator has to go to the installation location of the air conditioner and use the signal return circuit carried to determine whether the communication abnormality has occurred in the indoor unit or the outdoor unit. Therefore, the operator has to go to the installation location again after the abnormality determination, and the labor of the operator cannot be sufficiently reduced.

[0010] Therefore, an object of the present invention is to provide a communication system including a first device and a second device capable of wired communication, which can specify which of the first communication circuit, the second communication circuit, and the electrical wiring has an abnormality when communication between the devices becomes impossible.

Means for Solving the Problems

[0011] A main aspect of the present invention relates to a communication system, comprising: a first device having a first communication circuit; a second device having a second communication circuit and capable of wired communication with the first device; an electrical wiring connected to the first device and the second device; a first microcomputer provided in the first device; and a second microcomputer provided in the second device. The first microcomputer and the second microcomputer perform periodic communication in which communication signals are exchanged at predetermined intervals via the first communication circuit and the second communication circuit. The electrical wiring includes a power supply electrical wiring through which power for communication supplied from a communication power supply of the first device to the second communication circuit is transmitted, and a communication electrical wiring through which the communication signals are transmitted. In the communication system according to this aspect, there is a first switch unit that switches between a short-circuit state in which a first power line intervening between the communication power supply and the power supply electrical wiring and a first communication line intervening between the communication electrical wiring and the first communication circuit are short-circuited, and an open state in which the first power line and the first communication line are open; a second switch unit that switches between a short-circuit state in which a second power line intervening between the power supply electrical wiring and the second communication circuit and a second communication line intervening between the communication electrical wiring and the second communication circuit are short-circuited, and an open state in which the second power line and the second communication line are open; and a third switch unit that is disposed on the power supply electrical wiring side relative to a position where the first switch unit in the first power line is connected, and switches between a short-circuit state and an open state. Here, when the periodic communication is being performed normally, the first switch unit and the second switch unit are in the open state, and the third switch unit is in the short-circuit state. And the communication system further includes a communication abnormality diagnosis unit that diagnoses which of the electrical wiring, the first communication circuit, and the second communication circuit has an abnormality by switching the first switch unit, the second switch unit, and the third switch unit to a state different from when the periodic communication was being performed normally when the periodic communication cannot be performed normally.

[0012] According to the communication system according to this aspect, when periodic communication between the first microcomputer and the second microcomputer becomes impossible, it is possible to identify which of the electrical wiring, the first communication circuit, and the second communication circuit has an abnormality.

[0013] In the communication system according to this aspect, when the periodic communication cannot be performed normally, the communication abnormality diagnosis unit may be configured to execute a first diagnosis process for diagnosing whether the first communication circuit is faulty by switching the first switch unit from an open state to a short-circuit state and switching the third switch unit from a short-circuit state to an open state.

[0014] For example, the first microcomputer may function as the communication abnormality diagnosis unit. In this case, the first microcomputer includes a communication output port that outputs the communication signal and a communication input port to which the communication signal is input. Before the first diagnosis process is performed, the first switch unit is switched from an open state to a short-circuit state and the third switch unit is switched from a short-circuit state to an open state. In the first diagnosis process, a first diagnosis signal is output from the communication output port to the first communication circuit, and when a signal different from the original signal input from the first communication circuit based on the first diagnosis signal is input to the communication input port when the communication power is supplied to the first communication circuit via the first switch unit, it is determined that the first communication circuit is faulty.

[0015] According to the above configuration, when the periodic communication cannot be performed normally, by switching the first switch unit from an open state to a short-circuit state and switching the third switch unit from a short-circuit state to an open state and executing the first diagnosis process, it is possible to determine whether the cause of the communication abnormality is a failure of the first communication circuit.

[0016] When configured as described above, further, when the communication abnormality diagnosis unit determines that the first communication circuit is not faulty by the first diagnosis process, the communication abnormality diagnosis unit switches the first switch unit from the short-circuited state to the open state and switches the second switch unit and the third switch unit from the open state to the short-circuited state, and may be configured to execute a second diagnosis process for diagnosing whether the electrical wiring is disconnected.

[0017] For example, the first microcomputer and the second microcomputer may function as the communication abnormality diagnosis unit. In this case, before the second diagnosis process is performed, the second microcomputer switches the second switch unit from the open state to the short-circuited state. The first microcomputer includes a communication output port that outputs the communication signal and a communication input port to which the communication signal is input. Before the second diagnosis process is performed, the first microcomputer switches the first switch unit from the short-circuited state to the open state and switches the third switch unit from the open state to the short-circuited state. In the second diagnosis process, a second diagnosis signal is output from the communication output port to the first communication circuit. When a signal different from the original signal input from the first communication circuit based on the second diagnosis signal is input to the communication input port when the communication power is supplied to the first communication circuit via the power electrical wiring, the second switch unit, and the communication electrical wiring, it is determined that the electrical wiring is disconnected.

[0018] According to the above configuration, when the first communication circuit is not faulty, by switching the first switch unit from the short-circuited state to the open state and switching the second switch unit and the third switch unit from the open state to the short-circuited state and executing the second diagnosis process, it is possible to determine whether the cause of the communication abnormality is a disconnection of the electrical wiring.

[0019] When configured as described above, further, when the communication abnormality diagnosis unit determines that the electrical wiring is not disconnected by the second diagnosis process, the communication abnormality diagnosis unit switches the second switch unit from the short-circuited state to the open state, and may be configured to execute a third diagnosis process for diagnosing whether the second communication circuit is faulty.

[0020] For example, the first microcomputer and the second microcomputer can function as the communication abnormality diagnosis unit. In this case, before the third diagnosis process is performed, the second microcomputer switches the second switch unit from the short-circuited state to the open state. The first microcomputer includes a communication output port that outputs the communication signal and a communication input port to which the communication signal is input. In the third diagnosis process, a third diagnosis signal is output from the communication output port to the first communication circuit, and when a signal different from the original signal input from the first communication circuit based on the third diagnosis signal when the communication power is supplied to the first communication circuit due to a short circuit of the electrical wiring harness is input to the communication input port, it is determined that the second communication circuit is faulty, and when the original signal is input to the communication input port, it is determined that the electrical wiring harness is short-circuited.

[0021] According to the above configuration, when the electrical wiring harness is not disconnected, by switching the second switch unit from the short-circuited state to the open state and executing the third diagnosis process, it is possible to determine whether the cause of the communication abnormality is a failure of the second communication circuit or a short circuit of the electrical wiring harness.

[0022] As described above, when a configuration is adopted such that the second diagnosis process is executed when the first communication circuit is not faulty, further, the communication abnormality diagnosis unit may be configured to determine that the second communication circuit is faulty when it is determined by the second diagnosis process that the electrical wiring harness is not disconnected.

[0023] According to the above configuration, when there is no failure in the first communication circuit and no disconnection in the electrical wiring harness, it is possible to identify that the second communication circuit is faulty.

[0024] In the communication system according to this aspect, it may further include a notification unit, and the communication abnormality diagnosis unit may be configured to cause the notification unit to notify which of the electrical wiring harness, the first communication circuit, and the second communication circuit has an abnormality.

[0025] According to the above configuration, when the notification unit performs notification, a user, a service technician, or the like can easily identify the location where the abnormality occurred.

Advantages of the Invention

[0026] As described above, according to the present invention, when communication between the first device and the second device becomes impossible, it is possible to provide a communication system capable of identifying which of the first communication circuit, the second communication circuit, and the electrical wiring has an abnormality.

[0027] The effects or significance of the present invention will become clearer from the following description of the embodiments. However, the embodiments shown below are merely examples when implementing the present invention, and the present invention is not limited to those described in the following embodiments at all.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0029] Hereinafter, a hot water supply system which is an embodiment of the communication system of the present invention will be described with reference to the drawings.

[0030] FIG. 1 is a schematic diagram showing the configuration of the hot water supply system 10.

[0031] The hot water supply system 10 is a so-called hybrid hot water supply system, and includes a hot water storage unit 100, a heat pump unit 200, an auxiliary heat source unit 300, and a remote controller 400. The hot water supply system 10 stores hot water in a hot water storage tank 110 provided in the hot water storage unit 100, and supplies the hot water in the hot water storage tank 110 to a water supply faucet 20. The low-temperature hot water in the hot water storage tank 110 is heated by circulating between the heat pump unit 200. Further, in the hot water supply system 10, the low-temperature hot water discharged from the hot water storage tank 110 can be heated by the auxiliary heat source unit 300 and supplied to the water supply faucet 20.

[0032] The water supply faucet 20 is, for example, a bathroom faucet with a shower. By supplying hot water from the water supply faucet 20 to the bathtub, the bathtub can be filled with hot water. Note that the water supply faucet 20 may be a kitchen faucet, a washbasin faucet, or the like.

[0033] The hot water storage unit 100 includes a hot water storage tank 110, a hot water storage circuit 120, and a hot water supply unit 130.

[0034] The hot water storage tank 110 is a vertically long tank. The hot water storage tank 110 stores hot water at a preset target temperature. The hot water storage tank 110 is in a full water state, and a temperature stratification is formed inside. The hot water is stored from the upper part of the hot water storage tank 110, and the part where the hot water is not stored becomes water. On the side surface of the hot water storage tank 110, a plurality of hot water temperature sensors 111 for measuring the hot water storage amount, which is the amount of hot water at the target temperature, are respectively provided at height positions corresponding to each hot water storage amount.

[0035] The hot water circulation circuit 120 includes a forward path 121, a return path 122, and a hot water circulation pump 123. The forward path 121 is connected to the lower part of the hot water storage tank 110 and the inlet of the condenser 213 of the heat pump unit 200. The return path 122 is connected to the upper part of the hot water storage tank 110 and the outlet of the condenser 213. The hot water circulation pump 123 is provided in the forward path 121 and circulates hot water between the hot water storage tank 110 and the condenser 213.

[0036] The hot water supply unit 130 includes a water supply path 131, a hot water outlet path 132, a branched water supply path 133, a mixed hot water outlet path 134, and a mixing valve 135. The water supply path 131 is connected to the water supply pipe and the lower end of the hot water storage tank 110. The hot water outlet path 132 is connected to the upper end of the hot water storage tank 110 and one inlet of the mixing valve 135. The branched water supply path 133 branches from the water supply path 131 and is connected to the other inlet of the mixing valve 135. The mixed hot water outlet path 134 is connected to the outlet of the mixing valve 135 and the water faucet 20. The mixing valve 135 mixes the hot water from the hot water outlet path 132 and the water from the branched water supply path 133 and flows them into the mixed hot water outlet path 134.

[0037] Note that temperature sensors (not shown) are provided in the water supply path 131, the hot water outlet path 132, and the mixed hot water outlet path 134 of the hot water supply unit 130, and a water volume sensor (not shown) is provided in the mixed hot water outlet path 134.

[0038] The heat pump unit 200 includes a heat pump mechanism 210. The heat pump mechanism 210 includes a circulation path 211 through which the heat medium circulates, a compressor 212, a condenser 213, an expansion valve 214, and an evaporator 215 arranged in the circulation path 211, and a blower fan 216.

[0039] When the compressor 212 operates, the heat medium compressed by the compressor 212 and heated to a high temperature passes through the condenser 213. The water flowing out from the hot water storage tank 110 and flowing through the forward path 121 exchanges heat with the high-temperature heat medium when passing through the condenser 213 and is heated to become hot water. The hot water flows through the return path 122 and returns to the hot water storage tank 110. The heat medium that has exited the condenser 213 passes through the expansion valve 214, expands, becomes low temperature, and passes through the evaporator 215. Outside air is sent to the evaporator 215 by the blower fan 216, and the heat medium passing through the evaporator 215 is warmed by the outside air and flows to the compressor 212.

[0040] In addition, a temperature sensor (not shown) for detecting the temperature of the hot water flowing through the return path 122 is provided in the hot water storage circuit 120.

[0041] The auxiliary heat source unit 300 includes an auxiliary heating circuit 310 and an auxiliary heat source machine 320. The auxiliary heating circuit 310 includes a water inlet path 311, a water outlet path 312, a circulation pump 313, and a proportional valve 314.

[0042] The water inlet path 311 is connected to a position near the hot water storage tank 110 of the hot water outlet path 132 and the secondary heat exchanger 322 of the auxiliary heat source machine 320. The water outlet path 312 is connected to a downstream side of the connection position of the water inlet path 311 in the hot water outlet path 132 and the primary heat exchanger 321 of the auxiliary heat source machine 320. The circulation pump 313 is provided in the water inlet path 311. The proportional valve 314 is provided in the water outlet path 312 and adjusts the amount of hot water flowing through the auxiliary heating circuit 310.

[0043] The auxiliary heat source machine 320 includes a primary heat exchanger 321, a secondary heat exchanger 322, a combustor 323, and a combustion fan 324. Air is sent from the combustion fan 324 to the combustor 323. The combustor 323 burns with gas and heats the primary heat exchanger 321 and the secondary heat exchanger 322. As a result, the hot water passing through the primary heat exchanger 321 and the secondary heat exchanger 322 is heated.

[0044] In addition, a water volume sensor (not shown) is provided in the water inlet path 311 of the auxiliary heat source unit 300, and a temperature sensor (not shown) is provided in the water outlet path 312.

[0045] The remote controller 400 is arranged in a bathroom or a kitchen and includes an operation unit 410 and a display unit 420. At the operation unit 410, various operations can be performed, such as an operation to set the hot water supply temperature. On the display unit 420, various information, such as the set hot water supply temperature, is displayed. The operation unit 410 and the display unit 420 may be constituted by a touch panel.

[0046] In the hot water supply system 10, a hot water storage operation, a hot water supply operation, and an auxiliary heat source hot water supply operation are performed.

[0047] When the amount of stored hot water in the hot water storage tank 110 becomes less than a preset lower limit amount of stored hot water, the hot water storage operation is started. The hot water storage operation is performed regardless of whether other operations, such as the hot water supply operation, are being performed, and other operations are also performed regardless of whether the hot water storage operation is being performed.

[0048] The hot water storage pump 123 and the heat pump mechanism 210 operate, water circulates between the hot water storage tank 110 and the hot water storage circuit 120, the hot water discharged from the lower side of the hot water storage tank 110 is heated by the heat pump mechanism 210 to become hot water at a target temperature, and this hot water is stored on the upper side of the hot water storage tank 110. When the amount of stored hot water in the hot water storage tank 110 reaches a preset upper limit amount of stored hot water (for example, a full amount of stored hot water), the hot water storage pump 123 and the heat pump mechanism 210 stop, and the hot water storage operation ends.

[0049] When the water faucet 20 is opened, if there is sufficient hot water stored in the hot water storage tank 110, the hot water supply operation is started. Water from the water pipe is supplied to the lower part of the hot water storage tank 110 through the water supply path 131, and hot water comes out from the upper part of the hot water storage tank 110. The hot water flowing out from the hot water storage tank 110 flows through the hot water outlet path 132 and reaches the mixing valve 135. On the other hand, the water branched from the water supply path 131 flows through the branched water supply path 133 and reaches the mixing valve 135. The hot water from the hot water outlet path 132 and the water from the branched water supply path 133 are mixed by the mixing valve 135. At this time, the mixing valve 135 is controlled so that hot water at a predetermined hot water supply temperature is generated. The hot water flowing out from the mixing valve 135 flows through the mixed hot water outlet path 134 and is discharged from the water faucet 20. When the water faucet 20 is closed, the hot water supply operation ends.

[0050] On the other hand, when the water faucet 20 is opened, if the amount of hot water stored in the hot water storage tank 110 is insufficient, the auxiliary heat source hot water supply operation is started. The circulation pump 313 and the auxiliary heat source unit 320 operate, and a part of the water flowing out from the hot water storage tank 110 into the hot water outlet path 132 is drawn into the water inlet path 311 and sent to the auxiliary heat source unit 320, where it is heated to become hot water. The hot water flows through the water outlet path 312 and merges with the water in the hot water outlet path 132. At this time, the proportional valve 314 is controlled so that the temperature of the hot water after merging reaches the target temperature, and the amount of hot water to be merged is adjusted. Similar to the hot water supply operation, the hot water flowing through the hot water outlet path 132 is mixed with the water from the branched water supply path 133 by the mixing valve 135, and the hot water at a predetermined hot water supply temperature flows through the mixed hot water outlet path 134 and is discharged from the water faucet 20. When the water faucet 20 is closed, the circulation pump 313 and the auxiliary heat source unit 320 stop, and the auxiliary heat source hot water supply operation ends.

[0051] The hot water storage unit 100 includes a first microcomputer 140 (hereinafter abbreviated as "first microcontroller 140") that controls the operations of a hot water storage pump 123, a mixing valve 135, etc. Further, the heat pump unit 200 includes a second microcomputer 220 (hereinafter abbreviated as "second microcontroller 220") that controls the operations of a heat pump mechanism 210 (compressor 212, blower fan 216), etc. The first microcontroller 140 and the second microcontroller 220 include a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc.

[0052] Wired communication is performed between the hot water storage unit 100, that is, the first microcontroller 140, and the heat pump unit 200, that is, the second microcontroller 220.

[0053] FIG. 2 is a diagram showing a configuration for the first microcontroller 140 of the hot water storage unit 100 and the second microcontroller 220 of the heat pump unit 200 to communicate with each other.

[0054] The hot water storage unit 100 is provided with a first communication circuit 150 for the first microcontroller 140 to perform wired communication. The first microcontroller 140 includes a communication output port 141 that outputs a communication signal and a communication input port 142 to which a communication signal is input, and these communication output port 141 and communication input port 142 are connected to the first communication circuit 150.

[0055] The heat pump unit 200 is provided with a second communication circuit 230 for the second microcontroller 220 to perform communication. The second microcontroller 220 includes a communication output port 221 that outputs a communication signal and a communication input port 222 to which a communication signal is input, and these communication output port 221 and communication input port 222 are connected to the second communication circuit 230.

[0056] The electrical wiring 500 is connected to the hot water storage unit 100 and the heat pump unit 200 using connectors 610 and 620, for example. The electrical wiring 500 is, for example, a two-core cable and includes a power electrical wiring 510 and a communication electrical wiring 520.

[0057] The hot water storage unit 100 has a communication power supply V11 that serves as a source of communication power. The communication power supply V11 has a predetermined DC voltage (for example, 12V). In the hot water storage unit 100, a first power line L11 is interposed between the communication power supply V11 and the power electrical wiring 510, and a first communication line L12 is interposed between the communication electrical wiring 520 and the first communication circuit 150. In the heat pump unit 200, a second power line L21 is interposed between the power electrical wiring 510 and the second communication circuit 230, and a second communication line L22 is interposed between the communication electrical wiring 520 and the second communication circuit 230.

[0058] The communication power from the communication power supply V11 is transmitted through the first power line L11, the power electrical wiring 510, and the second power line L21 and supplied to the second communication circuit 230. Communication signals from the first communication circuit 150 and the second communication circuit 230 are transmitted through the first communication line L12, the communication electrical wiring 520, and the second communication line L22.

[0059] A first switch unit 161 is disposed between the first power line L11 and the first communication line L12. The first switch unit 161 is constituted by a switching circuit including a transistor such as a FET (Field-Effect Transistor), for example. The first switch unit 161 is controlled by the first microcomputer 140 as shown by the dashed arrow in FIG. 2, and switches between a short-circuit state in which the first power line L11 and the first communication line L12 are short-circuited and an open state in which the first power line L11 and the first communication line L12 are open.

[0060] A second switch unit 241 is disposed between the second power line L21 and the second communication line L22. The second switch unit 241 is constituted by, for example, a switching circuit including a transistor such as an FET. As shown by the dashed arrows in FIG. 2, the second switch unit 241 is controlled by the second microcomputer 220, and switches between a short-circuit state in which the second power line L21 and the second communication line L22 are short-circuited and an open state in which the second power line L21 and the second communication line L22 are open. Note that an insulated switching element is interposed in a control line connecting the second microcomputer 220 and the second switch unit 241, and the second microcomputer 220 and the second switch unit 241 are electrically insulated from each other.

[0061] A third switch unit 162 is disposed on the power electrical wiring 510 side of the first switch unit 161 connected to the first power line L11. The third switch unit 162 is constituted by, for example, a switching circuit including a transistor such as an FET. As shown by the dashed arrows in FIG. 2, the third switch unit 162 is controlled by the first microcomputer 140, and switches between a short-circuit state and an open state.

[0062] The first communication circuit 150 has a first signal line L13 connecting between a communication input port 142 of the first microcomputer 140 and ground (GND). The first switching element SW11 and the second switching element SW12 are disposed in this order on the first signal line L13 from the communication input port 142 side. The first switching element SW11 and the second switching element SW12 are, for example, transistors.

[0063] The first switching element SW11 is connected to the first communication line L12, turns on when power is input from the first communication line L12, and switches from an open state to a short-circuit state. The second switching element SW12 is connected to the communication output port 141 of the first microcomputer 140, turns on when a high-level signal is input from the communication output port 141, and switches from an open state to a short-circuit state.

[0064] The second communication circuit 230 includes a second signal line L23 connecting between the second power line L21 and the second communication line L22, and a third signal line L24 connecting between the communication input port 222 of the second microcontroller 220 and the ground (GND). A first insulated switching element SW21 is arranged on the third signal line L24, and a second insulated switching element SW22 is arranged on the second signal line L23. The first insulated switching element SW21 and the second insulated switching element SW22 are, for example, photocouplers or transformers. The second communication circuit 230 and the second microcontroller 220 are electrically insulated by the first insulated switching element SW21 and the second insulated switching element SW22.

[0065] The first insulated switching element SW21 is connected to the second signal line L23 and turns on when power is input from the second signal line L23, switching from an open state to a short-circuit state. The second insulated switching element SW22 is connected to the communication output port 221 of the second microcontroller 220 and turns on when a high-level signal is input from the communication output port 221, switching from an open state to a short-circuit state.

[0066] The first microcontroller 140 and the second microcontroller 220 perform periodic communication to exchange communication signals at predetermined intervals via the first communication circuit 150 and the second communication circuit 230. The communication signal transmitted from the first microcontroller 140 to the second microcontroller 220 is, for example, a control signal for operating / stopping the heat pump mechanism 210. In this case, while the heat pump mechanism 210 is stopped, a control signal instructing the stop is continuously transmitted periodically, and while the heat pump mechanism 210 is operating, a control signal instructing the operation is continuously transmitted periodically. The communication signal transmitted from the second microcontroller 220 to the first microcontroller 140 is, for example, a response signal in response to the control signal from the first microcontroller 140.

[0067] FIG. 3 is a diagram for explaining the periodic communication performed between the first microcontroller 140 and the second microcontroller 220.

[0068] When there is no communication abnormality between the first microcomputer 140 and the second microcomputer 220 and periodic communication is possible, the first switch unit 161 and the second switch unit 241 are in an open state, and the third switch unit 162 is in a short-circuited state.

[0069] As shown in FIG. 3, when communication is not being performed, high-level signals continue to be output from the communication output ports 141 and 221 of the first microcomputer 140 and the second microcomputer 220. In the first communication circuit 150, the second switching element SW12 is turned on by the high-level signal from the communication output port 141. In the second communication circuit 230, the second insulated switching element SW22 is turned on by the high-level signal from the communication output port 221. As a result, a current based on the communication power supplied to the second communication circuit 230 flows to the ground of the first communication circuit 150. In the first communication circuit 150, power is input to the first switching element SW11 and the first switching element SW11 is turned on, and the communication input port 142 of the first microcomputer 140 is connected to the ground, and a low-level signal continues to be input to the communication input port 142. In the second communication circuit 230, power is input to the first insulated switching element SW21 and the first insulated switching element SW21 is turned on, and the communication input port 222 of the second microcomputer 220 is connected to the ground, and a low-level signal continues to be input to the communication input port 222.

[0070] When the communication output port 141 of the first microcontroller 140 switches from a high-level signal to a low-level signal, the second switching element SW12 turns off, so that the current based on the communication power no longer flows to the ground of the first communication circuit 150. In the second communication circuit 230, since the power input stops and the first insulated switching element SW21 turns off, the communication input port 222 of the second microcontroller 220 is disconnected from the ground, and a high-level signal is input to the communication input port 222. Therefore, as shown in FIG. 3, when communication is started and a pulsed communication signal (for example, a control signal) that switches between a low-level signal and a high-level signal is output from the communication output port 141 of the first microcontroller 140, a pulsed communication signal with a phase inverted from the communication signal from the first microcontroller 140 is input to the communication input port 222 of the second microcontroller 220. Although the phase of the input communication signal is inverted, it is recognized as a communication signal from the first microcontroller 140 in the second microcontroller 220.

[0071] In this way, the communication signal output from the first microcontroller 140 is transmitted through the first communication circuit 150, the communication electrical wiring 520, and the second communication circuit 230 and input to the second microcontroller 220.

[0072] Note that due to the configuration of the first communication circuit 150, when the communication output port 141 of the first microcontroller 140 switches from a high-level signal to a low-level signal, the input of the communication input port 142 of the first microcontroller 140 also switches to a high-level signal. For this reason, when a communication signal is output from the communication output port 141, a communication signal with an inverted phase is also input to the communication input port 142.

[0073] When the communication output port 221 of the second microcomputer 220 switches from a high-level signal to a low-level signal, the second insulated switching element SW22 turns off, so that the current based on the communication power no longer flows to the ground of the first communication circuit 150. In the first communication circuit 150, since the power input stops and the first switching element SW11 turns off, the communication input port 142 of the first microcomputer 140 is disconnected from the ground, and a high-level signal is input to the communication input port 142. Therefore, as shown in FIG. 3, when a pulse-shaped communication signal (for example, a response signal) that switches between a low-level signal and a high-level signal is output from the communication output port 221 of the second microcomputer 220 following the communication signal from the first microcomputer 140, a pulse-shaped communication signal with an inverted phase from the communication signal of the second microcomputer 220 is input to the communication input port 142 of the first microcomputer 140. Although the phase of the input communication signal is inverted, it is recognized as a communication signal from the second microcomputer 220 in the first microcomputer 140.

[0074] In this way, the communication signal output from the second microcomputer 220 is transmitted through the second communication circuit 230, the communication electrical wiring 520, and the first communication circuit 150 and input to the first microcomputer 140.

[0075] Note that due to the configuration of the second communication circuit 230, when the communication output port 221 of the second microcomputer 220 switches from a high-level signal to a low-level signal, the first insulated switching element SW21 also turns off, so that the input of the communication input port 222 of the second microcomputer 220 also switches to a high-level signal. For this reason, when a communication signal is output from the communication output port 221, a communication signal with an inverted phase is also input to the communication input port 222.

[0076] Now, when a disconnection, short circuit occurs in the electrical wiring 500 (electrical wiring 510 for power use, electrical wiring 520 for communication use), a failure occurs in the first communication circuit 150, or a failure occurs in the second communication circuit 230, periodic communication cannot be performed between the hot water storage unit 100, that is, the first microcomputer 140, and the heat pump unit 200, that is, the second microcomputer 220. In the hot water supply system 10 of the present embodiment, when such a communication abnormality occurs, it is provided with a communication abnormality diagnosis function for diagnosing where an abnormality has occurred in any of the electrical wiring 500, the first communication circuit 150, and the second communication circuit 230. The first microcomputer 140 and the second microcomputer 220 function as a communication abnormality diagnosis unit that executes the communication abnormality diagnosis function.

[0077] When the communication abnormality diagnosis unit (the first microcomputer 140, the second microcomputer 220) cannot perform periodic communication normally (a communication abnormality has occurred), it switches the first switch unit 161, the second switch unit 241, and the third switch unit 162 to a state different from when periodic communication was being performed normally, thereby diagnosing where an abnormality has occurred in any of the electrical wiring 500, the first communication circuit 150, and the second communication circuit 230. Then, the communication abnormality diagnosis unit causes the remote controller 400, which is the notification unit, to notify where an abnormality has occurred in any of the electrical wiring 500, the first communication circuit 150, and the second communication circuit 230. More specifically, when periodic communication cannot be performed normally, the communication abnormality diagnosis unit switches the first switch unit 161 from the open state to the short-circuit state and switches the third switch unit 162 from the short-circuit state to the open state, and executes a first diagnosis process for diagnosing whether the first communication circuit 150 has failed. Further, when it is determined that the first communication circuit 150 has not failed, the communication abnormality diagnosis unit switches the first switch unit 161 from the short-circuit state to the open state and switches the second switch unit 241 and the third switch unit 162 from the open state to the short-circuit state, and executes a second diagnosis process for diagnosing whether the electrical wiring 500 is disconnected. Furthermore, when it is determined by the second diagnosis process that the electrical wiring 500 is not disconnected, the communication abnormality diagnosis unit switches the second switch unit 241 from the short-circuit state to the open state, and executes a third diagnosis process for diagnosing whether the second communication circuit 230 has failed.

[0078] FIG. 4 is a flowchart showing control processing executed by the first microcomputer 140 as a communication abnormality diagnosis unit. FIG. 5 is a flowchart showing control processing executed by the second microcomputer 220 as a communication abnormality diagnosis unit. FIG. 6 is a diagram for explaining the first diagnosis process. FIG. 7 is a diagram for explaining the second diagnosis process. FIG. 8 is a diagram for explaining the third diagnosis process.

[0079] Referring to FIG. 4, the first microcomputer 140 determines whether a communication abnormality has occurred based on whether periodic communication can be performed normally every predetermined time (S101). That is, if the first microcomputer 140 does not receive a communication signal from the second microcomputer 220 even after the restriction time has elapsed since transmitting a communication signal to the second microcomputer 220, the first microcomputer 140 transmits a communication signal to the second microcomputer 220 again. If the first microcomputer 140 does not receive a communication signal from the second microcomputer 220 even after transmitting the communication signal a specified number of times, it is determined that a communication abnormality has occurred because the periodic communication could not be performed normally.

[0080] When the first microcomputer 140 determines that a communication abnormality has occurred (S101: YES), it waits for the first waiting time to elapse (S102). Note that when the first microcomputer 140 determines that a communication abnormality has occurred, it interrupts the subsequent transmission of periodic communication signals.

[0081] Referring to FIG. 5, the second microcomputer 220 determines whether a communication abnormality has occurred based on whether the reception of a periodic communication signal from the first microcomputer 140 has stopped (S201). That is, when the first microcomputer 140 interrupts the transmission of a communication signal based on the determination that a communication abnormality has occurred, in the second microcomputer 220, the transmission signal is not received even after the time corresponding to two reception timings has elapsed from the reception timing of the previous transmission signal. Therefore, in this case, the second microcomputer 220 determines that a communication abnormality has occurred because the periodic communication signal from the first microcomputer 140 has stopped.

[0082] In this way, in the second microcomputer 220, the determination of communication abnormality is slower than that in the first microcomputer 140. Therefore, the first microcomputer 140 waits for the first waiting time to wait for the second switch unit 241 to finish the determination of communication abnormality. The first waiting time is set so that the second switch unit 241 finishes the determination of communication abnormality before that time elapses.

[0083] Returning to FIG. 4, when the first waiting time elapses (S102: YES), the first microcomputer 140 switches the first switch unit 161 from the open state to the short-circuit state and switches the third switch unit 162 from the short-circuit state to the open state (S103). Then, the first microcomputer 140 executes the first diagnostic process (S104).

[0084] In the state where the first switch unit 161 is short-circuited and the third switch unit 162 is open, the communication power from the communication power supply V11 is supplied to the first communication circuit 150 via the first switch unit 161.

[0085] As shown in FIG. 6, in the first diagnostic process, the first microcomputer 140 outputs a first diagnostic signal from the communication output port 141 to the first communication circuit 150. That is, the first microcomputer 140 outputs a predetermined pulse signal as the first diagnostic signal. At this time, if the first communication circuit 150 operates normally in a state where communication power is supplied via the first switch unit 161, the first switching element SW11 is turned on by the input of the communication power, and the second switching element SW12 is turned off and on by the input of the pulse signal. As a result, a pulse signal whose phase is inverted with respect to the first diagnostic signal is input to the communication input port 142 as the original signal. On the other hand, when the first communication circuit 150 is faulty, for example, when at least one of the first switching element SW11 and the second switching element SW12 is faulty, a continuous high-level signal or low-level signal is input to the communication input port 142 as a signal different from the original signal. As a result of outputting the first diagnostic signal, when a signal different from the original signal is input to the communication input port 142, the first microcomputer 140 determines that the first communication circuit 150 is faulty, and when the original signal is input to the communication input port 142, determines that the first communication circuit 150 is not faulty.

[0086] When the first microcomputer 140 determines that the first communication circuit 150 is faulty (S105: YES), it notifies the remote controller 400 that the first communication circuit 150 is faulty by transmitting a notification indicating that the first communication circuit 150 is faulty, so that the remote controller 400 is notified of the failure of the first communication circuit 150 in addition to the occurrence of a communication abnormality (S106). For example, in the remote controller 400, a notification screen for notifying that a communication abnormality has occurred and that the cause of the abnormality is a failure of the first communication circuit 150 is displayed on the display unit 420.

[0087] Returning to FIG. 5, when the second microcomputer 220 determines that a communication abnormality has occurred (S201: YES), it then switches the second switch unit 241 from the open state to the short-circuit state (S202). This switching of the second switch unit 241 does not have to be performed immediately after the occurrence of the communication abnormality, and may be performed until the first microcomputer 140 finishes the first diagnostic process.

[0088] Returning to FIG. 4, when the first microcomputer 140 determines that the first communication circuit 150 is not faulty (S105: NO), the first switch unit 161 is switched from the short-circuited state to the open state, and the third switch unit 162 is switched from the open state to the short-circuited state (S107). Then, the first microcomputer 140 executes the second diagnostic process (S108). At this time, as described above, the second switch unit 241 has already been switched to the short-circuited state. In a state where the first switch unit 161 is open and the second switch unit 241 and the third switch unit 162 are short-circuited, the communication power from the communication power supply V11 is supplied to the first communication circuit 150 via a path passing through the electrical wiring 510 for power, the second switch unit 241, and the electrical wiring 520 for communication.

[0089] As shown in FIG. 7, in the second diagnostic process, the first microcomputer 140 outputs a second diagnostic signal from the communication output port 141 to the first communication circuit 150. That is, the first microcomputer 140 continuously outputs a high-level signal as the second diagnostic signal. At this time, if the communication power is supplied to the first communication circuit 150 via the above path, the first switching element SW11 is turned on by the input of the communication power, and the second switching element SW12 is turned on by the input of the high-level signal. Therefore, a low-level signal is input to the communication input port 142 as the original signal. On the other hand, when the electrical wiring 500 is disconnected, that is, at least one of the electrical wiring 510 for power and the electrical wiring 520 for communication is disconnected, the communication power is not supplied to the first communication circuit 150. Therefore, the first switching element SW11 is turned off, and a high-level signal is input to the communication input port 142 as a signal different from the original signal. As a result of outputting the second diagnostic signal, when a signal different from the original signal is input to the communication input port 142, the first microcomputer 140 determines that the electrical wiring 500 is disconnected, and when the original signal is input to the communication input port 142, the first microcomputer 140 determines that the electrical wiring 500 is not disconnected.

[0090] When the first microcomputer 140 determines that the electrical wiring 500 is disconnected (S109: YES), it notifies the remote controller 400 that the electrical wiring 500 is disconnected by transmitting a notification, causing the remote controller 400 to be informed of the disconnection of the electrical wiring 500 in addition to the occurrence of a communication abnormality (S110). For example, on the remote controller 400, a notification screen that notifies that a communication abnormality has occurred and that the cause of the abnormality is the disconnection of the electrical wiring 500 is displayed on the display unit 420.

[0091] When the first microcomputer 140 determines that the electrical wiring 500 is not disconnected (S109: NO), it waits for the second waiting time to elapse (S111).

[0092] Returning to FIG. 5, when the second microcomputer 220 switches the second switch unit 241 to the short-circuited state (S202), it waits for the third waiting time to elapse (S203). The third waiting time is set to a time such that the first microcomputer 140 can complete the second diagnostic process of S108 before that time elapses. When the third waiting time elapses (S203: YES), the second microcomputer 220 switches the second switch unit 241 from the short-circuited state to the open state and switches the output of the communication output port 221 from the high-level signal to the low-level signal (S204).

[0093] Returning to FIG. 4, when the second waiting time elapses, the switching of the second switch unit 241 and the communication output port 221 in S204 of FIG. 5 is completed. As a result, the states of the first switch unit 161, the second switch unit 241, and the third switch unit 162 return to their original states, that is, the states when regular communication is being performed normally. When the second waiting time elapses (S111: YES), the first microcomputer 140 executes the third diagnostic process (S112).

[0094] As shown in FIG. 9, in the third diagnostic process, the first microcomputer 140 outputs a third diagnostic signal from the communication output port 141 to the first communication circuit 150. That is, the first microcomputer 140 outputs a predetermined pulse signal as the third diagnostic signal. At this time, if the electrical wiring 500 is short-circuited, a pulse signal with an inverted phase with respect to the third diagnostic signal is input to the communication input port 142 as the original signal input when the electrical wiring 500 is short-circuited, in the same case where the third switch unit 162 is in the open state and the first switch unit 161 is in the short-circuited state. On the other hand, when the electrical wiring 500 is not short-circuited, a signal different from the original signal is input to the communication input port 142. For example, when the second insulated switching element SW22 fails and remains off, a high-level signal continues to be input to the communication input port 142 regardless of the output of the third diagnostic signal. As a result of outputting the third diagnostic signal, when the original signal is input to the communication input port 142, the first microcomputer 140 determines that the electrical wiring 500 is short-circuited, and when a signal different from the original signal is input to the communication input port 142, it is determined that the electrical wiring 500 is not short-circuited, that is, since there is no failure in the first communication circuit 150 and no disconnection or short-circuit in the electrical wiring 500, it is determined that the second communication circuit 230 is faulty.

[0095] When the first microcomputer 140 determines that the electrical wiring 500 is short-circuited (S113: YES), it notifies the remote controller 400 that the electrical wiring 500 is short-circuited by transmitting a notification indicating that the electrical wiring 500 is short-circuited, causing the remote controller 400 to notify the short-circuit of the electrical wiring 500 in addition to the occurrence of a communication abnormality (S114). For example, on the remote controller 400, a notification screen for notifying that a communication abnormality has occurred and that the cause of the abnormality is a short-circuit of the electrical wiring 500 is displayed on the display unit 420.

[0096] On the other hand, when the first microcomputer 140 determines that the second communication circuit 230 has failed (S113: NO), it notifies the remote controller 400 that the second communication circuit 230 has failed by transmitting a notice indicating that the second communication circuit 230 has failed, thereby causing the remote controller 400 to notify the failure of the second communication circuit 230 in addition to the occurrence of a communication abnormality (S115). For example, on the remote controller 400, a notification screen that notifies that a communication abnormality has occurred and that the cause of the abnormality is a failure of the second communication circuit 230 is displayed on the display unit 420.

[0097] When a user who notices a communication abnormality between the hot water storage unit 100 and the heat pump unit 200 requests repair from a service company, the user can inform which of the electrical wiring 500, the first communication circuit 150, and the second communication circuit 230 has a problem. As a result, the service company can identify the location of the problem, bring the corresponding parts, etc. to the installation location of the hot water supply system 10, and perform the repair. Therefore, it is not necessary for a service technician or the like to visit the installation location once to check the problem location and then visit the installation location again after preparing the parts, etc., and efficient repair can be performed.

[0098] <Effects of the Embodiment> According to the present embodiment, the following effects can be achieved.

[0099] When periodic communication between the first microcomputer 140 of the hot water storage unit 100 and the second microcomputer 220 of the heat pump unit 200 becomes impossible, it is possible to identify which of the electrical wiring 500, the first communication circuit 150 of the hot water storage unit 100, and the second communication circuit 230 of the heat pump unit 200 has an abnormality.

[0100] Furthermore, since the remote controller 400 notifies which of the electrical wiring 500, the first communication circuit 150, and the second communication circuit 230 has an abnormality, users, service technicians, etc. can easily identify the location that causes the abnormality.

[0101] Furthermore, when the periodic communication cannot be performed normally, by switching the first switch unit 161 from the open state to the short-circuit state and switching the third switch unit 162 from the short-circuit state to the open state and executing the first diagnostic process, it is possible to determine whether the cause of the communication abnormality is a failure of the first communication circuit 150.

[0102] Furthermore, when the first communication circuit 150 is not faulty, by switching the first switch unit 161 from the short-circuit state to the open state and switching the second switch unit 241 and the third switch unit 162 from the open state to the short-circuit state and executing the second diagnostic process, it is possible to determine whether the cause of the communication abnormality is a disconnection of the electrical wiring 500.

[0103] Furthermore, when the electrical wiring 500 is not disconnected, by switching the second switch unit 241 from the short-circuit state to the open state and executing the third diagnostic process, it is possible to determine whether the cause of the communication abnormality is a failure of the second communication circuit 230 or a short circuit of the electrical wiring 500.

[0104] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited by the above embodiments, and various modifications other than the above are possible for the embodiments of the present invention.

[0105] <Modification Example 1> FIG. 9 is a flowchart showing the control process executed by the first microcomputer 140 as a communication abnormality diagnosis unit according to Modification Example 1.

[0106] In the electrical wiring 500, it is very unlikely that the power electrical wiring 510 and the communication electrical wiring 520 short-circuit. Therefore, when a communication abnormality occurs, it is rare for the cause to be a short circuit of the electrical wiring 500. Therefore, when there is no failure in the first communication circuit 150 and no disconnection in the electrical wiring 500, it can also be regarded that the second communication circuit 230 is faulty.

[0107] Therefore, in this modified example, when the third diagnostic process is not executed and it is determined by the second diagnostic process that the electrical wiring harness 500 is not disconnected, it is determined that the second communication circuit 230 is faulty.

[0108] As shown in FIG. 9, in the second diagnostic process of S108, when a signal different from the original signal is input to the communication input port 142 as a result of the first microcomputer 140 outputting a second diagnostic signal, the first microcomputer 140 determines that the electrical wiring harness 500 is disconnected. When the original signal is input to the communication input port 142, it is determined that the electrical wiring harness 500 is not disconnected, that is, since there is no fault in the first communication circuit 150 nor a disconnection in the electrical wiring harness 500, it is determined that the second communication circuit 230 is faulty.

[0109] Then, when the first microcomputer 140 determines in S109 that the second communication circuit 230 is faulty (S109: NO), it causes the remote controller 400 to notify of the fault in the second communication circuit 230 (S115).

[0110] Note that in this modified example, since the third diagnostic process is not executed, in the control process shown in FIG. 5, the second microcomputer 220 does not execute the processes of S203 and S204.

[0111] Also according to this modified example, when periodic communication cannot be performed between the first microcomputer 140 and the second microcomputer 220, it is possible to identify which of the electrical wiring harness 500, the first communication circuit 150, and the second communication circuit 230 has an abnormality.

[0112] <Other Modified Examples> In the above embodiment, the hot water storage unit 100 includes, as a first device, a communication power supply V11, a first switch unit 161, a third switch unit 162, and a first communication circuit 150, and the heat pump unit 200 includes, as a second device, a second switch unit 241 and a second communication circuit 230. However, the heat pump unit 200 may include, as a first device, a communication power supply V11, a first switch unit 161, a third switch unit 162, and a first communication circuit 150, and the hot water storage unit 100 may include, as a second device, a second switch unit 241 and a second communication circuit 230.

[0113] Furthermore, in the above embodiment, as an example of the communication system of the present invention, a hot water supply system 10 including a hot water storage unit 100 as a first device and a heat pump unit 200 as a second device is shown. However, the present invention can also be applied to a hot water supply system in which a fuel cell unit is used instead of the heat pump unit 200 as a heat source unit for heating the hot water in the hot water storage tank 110 of the hot water storage unit 100. The fuel cell unit heats the hot water in the hot water storage tank 110 by using the heat discharged during power generation in the fuel cell. Furthermore, the present invention can also be applied to a communication system including a first device and a second device capable of wired communication other than the hot water supply system, such as an air conditioning system including an indoor unit and an outdoor unit capable of wired communication.

[0114] In addition, the embodiments of the present invention can be appropriately changed within the scope described in the claims.

Explanation of Reference Numerals

[0115] 10 Hot water supply system (communication system) 100 Hot water storage unit (first device) 140 First microcomputer (communication abnormality diagnosis unit) 150 First communication circuit 161 First switch unit 162 Third switch unit 200 Heat pump unit (second device) 220 Second microcomputer (communication abnormality diagnosis unit) 230 Second communication circuit 241 Second switch section 400 Remote controller (notification section) 500 Electrical wiring 510 Electrical wiring for power 520 Electrical wiring for communication V11 Communication power supply L11 First power line L12 First communication line L21 Second power line L22 Second communication line

Claims

1. A first device having a first communication circuit, A second device having a second communication circuit and capable of wired communication with the first device, An electrical wiring connected to the first device and the second device, A first microcomputer provided in the first device, A second microcomputer provided in the second device, and comprising: The first microcomputer and the second microcomputer perform periodic communication in which communication signals are exchanged at predetermined time intervals via the first communication circuit and the second communication circuit, In a communication system, the electrical wiring includes a power supply electrical wiring through which power for communication supplied from a communication power supply of the first device to the second communication circuit is transmitted, and a communication electrical wiring through which the communication signal is transmitted, A first switch unit that switches between a short-circuit state in which a first power line intervening between the communication power supply and the power supply electrical wiring and a first communication line intervening between the communication electrical wiring and the first communication circuit are short-circuited, and an open state in which the first power line and the first communication line are open, A second switch unit that switches between a short-circuit state in which a second power line intervening between the power supply electrical wiring and the second communication circuit and a second communication line intervening between the communication electrical wiring and the second communication circuit are short-circuited, and an open state in which the second power line and the second communication line are open, A third switch unit that is disposed on the power supply electrical wiring side with respect to a position where the first switch unit in the first power line is connected and switches between a short-circuit state and an open state, When the periodic communication is being performed normally, the first switch unit and the second switch unit are in an open state, and the third switch unit is in a short-circuit state, When the periodic communication cannot be performed normally, the first switch unit, the second switch unit, and the third switch unit are switched to a state different from when the periodic communication was being performed normally, thereby diagnosing which of the electrical wiring, the first communication circuit, and the second communication circuit has an abnormality. Further comprising a communication abnormality diagnosis unit, A communication system characterized by the above.

2. In the communication system according to claim 1, When the periodic communication cannot be performed normally, the communication abnormality diagnosis unit switches the first switch unit from the open state to the short-circuit state and switches the third switch unit from the short-circuit state to the open state, and executes a first diagnosis process for diagnosing whether the first communication circuit is faulty. A communication system characterized by the above.

3. In the communication system according to claim 2, the first microcomputer functions as the communication abnormality diagnosis unit, the first microcomputer includes a communication output port for outputting the communication signal and a communication input port for inputting the communication signal, before the first diagnosis process is performed, the first switch unit is switched from the open state to the short-circuit state and the third switch unit is switched from the short-circuit state to the open state, in the first diagnosis process, a first diagnosis signal is output from the communication output port to the first communication circuit, and when a signal different from the original signal input from the first communication circuit based on the first diagnosis signal is input to the communication input port when the communication power is supplied to the first communication circuit via the first switch unit, it is determined that the first communication circuit is faulty. A communication system characterized by the above.

4. In the communication system according to claim 2, when the communication abnormality diagnosis unit determines that the first communication circuit is not faulty by the first diagnosis process, the first switch unit is switched from the short-circuit state to the open state, and the second switch unit and the third switch unit are switched from the open state to the short-circuit state, and a second diagnosis process for diagnosing whether the electrical wiring is disconnected is executed. A communication system characterized by the above.

5. In the communication system according to claim 4, the first microcomputer and the second microcomputer function as the communication abnormality diagnosis unit, before the second diagnosis process is performed, the second microcomputer switches the second switch unit from the open state to the short-circuit state, the first microcomputer includes a communication output port for outputting the communication signal and a communication input port for inputting the communication signal, before the second diagnosis process is performed, the first switch unit is switched from the short-circuit state to the open state and the third switch unit is switched from the open state to the short-circuit state, In the second diagnostic process, a second diagnostic signal is output from the communication output port to the first communication circuit, and when the communication power is supplied to the first communication circuit via the electrical wiring harness, the second switch unit, and the communication electrical wiring harness, if a signal different from the original signal input from the first communication circuit based on the second diagnostic signal is input to the communication input port, it is determined that the electrical wiring harness is disconnected. A communication system characterized by the above.

6. In the communication system according to claim 4, when the communication abnormality diagnosis unit determines that the electrical wiring harness is not disconnected by the second diagnostic process, the second switch unit is switched from the short-circuited state to the open state, and a third diagnostic process for diagnosing whether the second communication circuit is faulty is executed. A communication system characterized by the above.

7. In the communication system according to claim 6, the first microcomputer and the second microcomputer function as the communication abnormality diagnosis unit, before the third diagnostic process is performed, the second microcomputer switches the second switch unit from the short-circuited state to the open state, the first microcomputer, includes a communication output port for outputting the communication signal and a communication input port for inputting the communication signal, in the third diagnostic process, a third diagnostic signal is output from the communication output port to the first communication circuit, and when a signal different from the original signal input from the first communication circuit based on the third diagnostic signal is input to the communication input port when the communication power is supplied to the first communication circuit due to a short circuit of the electrical wiring harness, it is determined that the second communication circuit is faulty, and when the original signal is input to the communication input port, it is determined that the electrical wiring harness is short-circuited. A communication system characterized by the above.

8. In the communication system according to claim 4, when the communication abnormality diagnosis unit determines that the electrical wiring harness is not disconnected by the second diagnostic process, it is determined that the second communication circuit is faulty. A communication system characterized by the above.

9. In the communication system according to any one of claims 1 to 8, further comprising a notification unit, the communication abnormality diagnosis unit causes the notification unit to notify which of the electrical wiring harness, the first communication circuit, and the second communication circuit has an abnormality. A communication system characterized by the above.

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