| 摘要 |
PURPOSE:To enable detection of an abnormal signal having slightly higher level than a normal signal by arranging a set value switching means in a level judging circuit and connecting the set value switching means through a communication means with a set value switching command means. CONSTITUTION:When a set value switching command circuit 13 on the side of a master station 7 is operated to transmit a switching command signal for switching the levels of set values Sa-Sd individually or simultaneously through a communication line 14 to a communication unit 5, the switching command signal is transmitted through selected signal lines 8a-8d, a memory means 11, a set value switching circuit 10 and a set value switching element 9 thus switching the levels of the set values Sa-Sd in a level judging circuit 3. Consequently, a signal fed from a detection unit 1 can be compared with a set value higher or lower than the initial set values Sa-Sd, and when the occurrence frequency of halfway level signals between a normal signal and a fault signal is counted, degradation of machinery on the line can be judged. |
