| 摘要 |
PROBLEM TO BE SOLVED: To provide duplicate transmission control, such as decision of an active system/a standby system and system changeover on the occurrence of faults without intervention of application on a controller. SOLUTION: The identical address is decide for duplicate control devices 2A, 2B and an identification number that can definitely identify each control device is decided, and an identification number of its own device and an opposite device is stored in the control devices 2A, 2B. When a control device rises, after a check frame to which an address and an identification number are added is broadcast, and when a response with respect to the check frame cannot received within a prescribed time, the device itself acts like an active system. Furthermore, when a control device acts as an active system and receives the frame from the other control device, the control device sends a check frame to the network as a response. When a control device receives a transmission response before becoming the active system and when the response includes an identification of the responded control device in pairs with the control device, the control device acts as a standby system, and when the response does not include the identification number, no transmission control is conducted afterwards.
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