| 摘要 |
PURPOSE:To grasp a working time of each input/output device, in the center side, by counting and storing a response signal showing that an input/output device is being operated, which is generated by the input/output device which has received an inquiry signal being sent out at constant time intervals. CONSTITUTION:A transmission and receiving device 2 sends out a poll signal P which has been generated, to input/output devices A-Z in order. When the signal P has been received, if the device A is being operated, a response signal Qa is sent out. The signal Qa is received by a transmitting and receiving circuit of the center side, and is sent to a counter 5. A detecting circuit 4 discriminates a device number of the signal Qa, and sends out a control signal J. The signal J drives a changeover controlling circuit 6 and connects a changeover switch S1 and S2 to a contact (a). Therefore, an accumulated value KA in a memory part MA is supplied to the counter 5. The counter 5 adds the accumulated value KA and the signal Qa, and its value is stored in the storage part MA. Accordingly, the product of the accumulated value KA, and a period of the signal P shows a working time which has elapsed, of the input/output device. |
