| 摘要 |
PURPOSE:To realize a communication control featuring the reduced overrun by having continuous counting of the scanning counter in case the priority order of the priority circuit is lower than the priority order of the circuit control part and then stopping the operation of the scanning counter in case the priority order is identical between them. CONSTITUTION:AND/OR circuits 10a, 10b ... are provided at circuit control parts 1a, 1b ... to give the priority signals to the scanning part when the process request is given. At the scanning part, the priority order of circuit control part 1 designated by scanning counter 2 is shown by priority circuit 13, and scanning control register 5 stops the start of counter 2. At the same time, the output signal of circuit 13 is compared 18 with the priority signal generated at part 1, and the process request is detected at part 1 via counter 2. And in case the priority order of the output signal at circuit 13 is lower than that at part 1, the operation of counter 2 is continued to carry out counting; while counter 2 is stopped in case the priority order is identical between them. In such way, the communication control becomes possible with reduced overrun. |
