| 摘要 |
PURPOSE:To reduce the work quantity of software and to prevent the processing capability of a central processing unit from being reduced, by setting a threshold for line signal change duration in accordance with monitor contents when the line signal is monitored. CONSTITUTION:A line signal 1 from a line which is not shown in figure is stored successively in memory 4 through a monitor means 2 and a noise eliminating means 3. Set times T1 and T2 (T1>T2) are set by software when a monitor instruction for the line signal is transmitted. A main storage device which is not shown in figure counts the line signal in the memory 4 at intervals of, for example, 2ms to monitor the line signal and measures a line signal duration (t). Comparators 6 and 7 compares set times T1 and T2 with the line signal duration (t); and when T1<(t) and T2<(t) are true, a line signal change information output 8 and a line signal duration output 9 are transmitted to the upper-level device. |
