| 摘要 |
PURPOSE:To prevent the system-down, by producing the failure information signal and making definite the time for retrial, if the retrial request is not released within the predetermined time even with repetitive retrials, through the addition of the response monitor circuit to the system. CONSTITUTION:With the request indication circuit 3 of the data transfer units 1, 2, the request signal 101 is fed to the common bus 100. This signal 101 is received with the transfer unit 1 or 2, and either one response signal out of the ACK response signal 102, NACK response signal 103 and WAIT response signal 104 is fed from the respective response circuit 4 to the common bus 100. Further, the transfer units 1, 2 operate the response monitor circuit 5 when the request signal 101 is transmitted to start the monitor of the response signal and the monitor is ended when the signals 102, 103 are received as response signal. Further, when the signal 104 is received, retrial is repetitively made and if the retrial is not released within predetermined time, failure information signal is produced to avoid the system-down. |
