PURPOSE: To complete accident prevention by repeatedly generating an alarm at intervals of a prescribed time at the time when the state variable of a process approaches a limit value set on the danger side beyond the upper limit or lower limit alarm level value.
CONSTITUTION: A CPU 6 is provided with a forgetting prevention alarm circuit 12, and this circuit 12 takes in the liquid level measured value from a detector 4 which is given from an A/D converter 5 at intervals of a prescribed sampling period, and the circuit 12 causes an alarm device 9 to generate an alarm when the liquid level measured value reaches an upper limit or lower limit alarm level PH or PL, and the circuit 12 generates an alarm at intervals of a prescribed sampling period when the liquid level measured value approaches the upper limit value beyond the upper limit alarm level PH or approaches the lower limit value beyond the lower limit alarm level PL. Thus, possibility of an accident is reduced.
NAGAYAMA KEIICHI
YAMASHITA HATSUO
Next Patent: ELECTROLUMINESCENT COUNT READ AND DISPLAY DEVICE