Abstract: A microcomputer is put into a sleep mode immediately when tasks become ready for the sleep mode so as to eliminate wasted power. Multiple application tasks are executed. Each application task provides notification regarding entry into sleep-ready state. When any application task provides notification, a status management section program sets a flag indicating that the application task goes to the sleep-ready state. The status management section checks flags of all the application tasks to determine whether all the application tasks go to the sleep-ready state, whereupon the microcomputer is put into the sleep mode.

Abstract: In a network system, each ECU transmits a start control frame when to start, and is started when it receives the start control frame from any other ECU during the stop of its operation. Besides, each ECU transmits a stop control frame cyclically during its operation, and continues its operation in spite of being capable of stopping its operation, while it is receiving the stop control frame from any other ECU. In transmitting each of the frames, each ECU affixes cause information expressive of a start cause or an operation stop incapability cause to the frame. In stopping a network, a supervisory device specifies the start ECU and the start cause thereof from the start control frame and stores them in a nonvolatile memory.

Abstract: A multiplex communication system includes a plurality of networks and a data relay unit. Each node included in each network resets a relay flag which is a predetermined bit of a data frame, when it sends the data frame to another node. If the data frame requires to be relayed, the data relay unit receives and relays the data frame. The data relay unit includes a relay flag check (RFC) section and a relay flag setting (RFS) section. The RFC section checks whether the relay flag of the data frame is set. If relay flag is set, the RFC section inhibits the data frame from being relayed. If the relay flag is not set, the RFC section allows the data frame to be relayed. The RFS section sets the relay flag of the data frame when the data frame is relayed.

Abstract: A microcomputer comprises an intermittent operation control section for intermittently operating a CPU. Moreover, the microcomputer comprises a timer block, a level detecting circuit or a timer interlocking control section as the circuits for assisting operation of the CPU. The CPU realizes a timer function with the timer block. The CPU can start the process in response to a level of an external signal with the level detecting circuit. The CPU can start operation with the timer interlocking control section after an external apparatus is driven. With the structure explained above, power consumption of the microcomputer is reduced.

Abstract: A multiplex communication system includes a plurality of networks and a data relay unit. When an event occurs in a node belonging to one of the networks, the node (sender node) sends a wake-up frame before it sends an event frame. In response to the wake-up frame, the nodes belonging to the same network which includes the sender node are activated and the data relay unit sends a wake-up frame to the respective networks for activating the networks. When it is determined that each of the networks is activated, the data relay unit sends a network activation notifying (NAN) frame regarding the network to all the networks. The NAN frame regarding the network represents that the network is activated. The sender node sends the event frame in response to the NAN frame regarding the destination network of the event frame.

Abstract: A plurality of electronic control units is continuously supplied with electric power to be capable of communication one another even when respective controlled devices are in inoperative condition. Each ECU transmits a sleep NG information along with its device ID when it not allowed to remain in the sleep mode. An abnormality detection unit connected to the ECUs through communication lines monitors the sleep NG information of each ECU to detect the ECU remaining activated for more than a wait period which is required for the ECU to shift to the sleep mode. The device ID of the ECU which is detected as remaining activated is stored in a memory so that any abnormal location may be specified by the stored device ID.

Abstract: In a network system, each ECU transmits a start control frame when to start, and is started when it receives the start control frame from any other ECU during the stop of its operation. Besides, each ECU transmits a stop control frame cyclically during its operation, and continues its operation in spite of being capable of stopping its operation, while it is receiving the stop control frame from any other ECU. In transmitting each of the frames, each ECU affixes cause information expressive of a start cause or an operation stop incapability cause to the frame. In stopping a network, a supervisory device specifies the start ECU and the start cause thereof from the start control frame and stores them in a nonvolatile memory.

Abstract: A microcomputer comprises an intermittent operation control section for intermittently operating a CPU. Moreover, the microcomputer comprises a timer block, a level detecting circuit or a timer interlocking control section as the circuits for assisting operation of the CPU. The CPU realizes a timer function with the timer block. The CPU can start the process in response to a level of an external signal with the level detecting circuit. The CPU can start operation with the timer interlocking control section after an external apparatus is driven. With the structure explained above, power consumption of the microcomputer is reduced.

Abstract: A multiplex communication system includes a plurality of networks and a data relay unit. Each node included in each network resets a relay flag which is a predetermined bit of a data frame, when it sends the data frame to another node. If the data frame requires to be relayed, the data relay unit receives and relays the data frame. The data relay unit includes a relay flag check (RFC) section and a relay flag setting (RFS) section. The RFC section checks whether the relay flag of the data frame is set. If relay flag is set, the RFC section inhibits the data frame from being relayed. If the relay flag is not set, the RFC section allows the data frame to be relayed. The RFS section sets the relay flag of the data frame when the data frame is relayed.

Abstract: A plurality of electronic control units is continuously supplied with electric power to be capable of communication one another even when respective controlled devices are in inoperative condition. Each ECU transmits a sleep NG information along with its device ID when it not allowed to remain in the sleep mode. An abnormality detection unit connected to the ECUs through communication lines monitors the sleep NG information of each ECU to detect the ECU remaining activated for more than a wait period which is required for the ECU to shift to the sleep mode. The device ID of the ECU which is detected as remaining activated is stored in a memory so that any abnormal location may be specified by the stored device ID.

Abstract: A multiplex communication system includes a plurality of networks and a data relay unit. When an event occurs in a node belonging to one of the networks, the node (sender node) sends a wake-up frame before it sends an event frame. In response to the wake-up frame, the nodes belonging to the same network which includes the sender node are activated and the data relay unit sends a wake-up frame to the respective networks for activating the networks. When it is determined that each of the networks is activated, the data relay unit sends a network activation notifying (NAN) frame regarding the network to all the networks. The NAN frame regarding the network represents that the network is activated. The sender node sends the event frame in response to the NAN frame regarding the destination network of the event frame.

Abstract: A multiplex communication system includes a data relay unit which has a plurality of send/receive (SR) sections. Communication lines are connected to the respective SR sections, and nodes are connected to the communication lines. The data relay unit further includes a destination table and header tables. In the data relay unit, a data frame sent from a node is received by one of the SR sections, and the SR sections which ought to send the data frame are identified by referring to the destination table. A header according to the appropriate communication protocol is formed by referring to one of the header tables. Further the data frame including the formed header is formed and sent to the destination node by the identified SR sections. When nodes are added or eliminated, this system can be reconfigured only by modifying or replacing the destination table and the header tables.