| 摘要 |
PURPOSE:To easily detect a fault in the stepping of a counter only through the addition of a simple hardware by discriminating the counter to be faulty when a detection means confirms that an output of a circuit latching parity is unchanged with the stepping of the counter. CONSTITUTION:A counter 1 in figure is operated so that the count is stepped every time an advance condition signal 10 is 'ON' (same definition as 'present'). An output signal 15 of a parity latch circuit 3 is compared with an output signal (count) 12 of the counter 1 by a parity check circuit 4, which generates a parity error output signal 13 if the parity is dissident. Moreover, a parity change detection circuit 5 has a function storing the output signal 15 of the parity latch circuit 3 depending on the preceding count and compares the parity of a new parity output signal 15 of the parity latch circuit 3 revised with the stepping condition signal 10 set to 'ON' with the stored parity by the preceding count to detect the coincidence. |
