| 摘要 |
PROBLEM TO BE SOLVED: To generate a warning signal which corresponds to a process value, without being affected by a hunting phenomenon even when a hunting period is long or when hunting width is large. SOLUTION: A process value outputted from a process being an object to be monitored is differentiated, and a differentiated value is generated by a differentiating circuit 3. When this differentiated value is changed to a decreasing direction prior to a constant time, and changed into an increasing direction at the present time, changing direction judging circuit 4 and 6 detect this. When a process value is exceeds a warning upper limit value, a size discriminating circuit 2 detects this, and generates an upper limit warning signal. |
