| 摘要 |
PURPOSE:To reuse a recovered slave station speedily and to repair a fault point speedily by allowing a master station to check the fault and recovery of a slave station at a specific period independently of the timing of the requesting of data transmission. CONSTITUTION:A CPU1 outputs data showing that there are slave stations RST41-RST4n to the master station MST2 and starts inquiring their states of the RSTs. This inquiry is performed periodically, and if there is abnormality in an answer from an RST, that is reported to the CPU1. Once the abnormality is detected, the inquiry is interrupted and the MST2 detects its recovery in a longer period for the recovery detectionof the RST. When the recovery of the RST is detected, that is reported to the CPU1, which then transmits and receives data to and from this RST. The MST2 performs self-returning operation in addition to said inquiry to test its transmitting and receiving circuit 6. |
