Change of value
A method used within a BAS/EMCS to collect data. A change of value (COV) threshold is the change that triggers the system to record a value in a trend log or communicate a new value to another location. Example: A temperature senor is located in a room at 70?F and has a COV threshold of 1?F. If activity in the room causes the temperature to increase to 70.9?F no action is taken. When the sensor reads 71.1?F, a new value is recorded in the trend log. The alternative to COV reporting is to record and transmit data at a fixed time internal, such as once every five minutes.