Description: The method of sampling the selected variable and calculating the value to be compared against the thresholds. If the value of this object is absoluteValue(1), the value of the selected variable will be compared directly with the thresholds at the end of the sampling interval. If the value of this object is deltaValue(2), the value of the selected variable at the last sample will be subtracted from the current value, and the difference compared with the thresholds.If the value of this object is changeratioValue(3),the value of the selected variable will be the change ratio of the selected variable, which is that the value of the selected variable at the last sample will be substracted from the current value,and the difference divided by the sampling interval,and the result compared with the thresholds.

This object may not be modified if the associated alarmStatus object is equal to valid(1).