I tried to use notification plug in and identified with some function is missing here. The notification can support the lower alarm unit, lower limit, higher alarm unit and higher limit as threshold. For example, if the higher alarm limit is 20, then the register value is 21 or above, the event is triggered with alarm alert. This is fine if there is a threshold.
But if the value is discrete value of 1 or 2 or 3, then the event cannot be triggered on this condition. I have tried this many times but there is no way to solve temporarily.