| 摘要 |
PURPOSE: To automatically monitor a filling level without depending on a characteristic of a filler by arranging a level sensor finding a filling level on the basis of a traveling time of an echo and a plurality of limit value transmitters additionally. CONSTITUTION: A level sensor 22 for a filling level measuring device 20 sends waves to a filler surface 19 so as to receive the waves (echo) reflected on the surface 19. A measuring circuit 24 finds a distance D from the sensor 22 to the surface 19 on the basis of a traveling time of the echo. From this distance D, a filling level F is found. In addition, a plurality of limit value transmitters 32, 34, 36, 38 are additionally installed in a container 10 at different heights. Each of these transmitters transmits an electric signal indicating whether the filling level F reaches the predetermined height or not. For example, if the filling level F exists between the transmitters 34, 36, the measuring circuit 24 detects this condition when the output signal of the transmitter 34 is provided with the first signal value while the output signal of the transmitter 36 is provided with the second signal value. |
