Emerson Rosemount 3308 Series Reference Manual page 218

Configuration parameters
February 2020
User defined alert
Variable
The variable selected for the alert.
Alert direction
Whether the alert will be triggered above or below the variable's value.
Limit
The variable value that will trigger the alert.
Note
Alert Limit values must be outside the Upper Null Zone, the Blind zones, and areas close to
the Blind Zones with reduced accuracy.
Deadband
An area of a variable's range where no action occurs to prevent alert from activating/
deactivating too quickly.
Lost measurement
Lost measurement behavior
Configure level value to report if measurement is lost unexpectedly. Choose one of the
following actions:
Table D-5: Lost Measurement Behavior Options
Option
Alarm (NaN Value/Bad Status)
Output Full Tank
Output Empty Tank
Number of measurements to hold level
The number of measurements the device will hold the current level if level measurement
has been lost. Then it will output level according to Lost Measurement Behavior, if still lost.
For an application where problems with lost measurement due to noise or weak surface
echoes are experienced, this parameter value could typically be increased.
The Hold Time value presents for how long the device will hold the current level. The time
the current level will be held is calculated out of a combination of both Number of
Measurements to Hold Level and the Update Rate.
Note
Make sure you have enough safety margin in your system to manage a delayed condition.
218
Description
If the measurement is lost, the level value will
report: "Not a Number / Bad Status".
If the measurement is lost, the level value will
correspond to full tank.
If the measurement is lost, the level value will
correspond to empty tank.
Reference Manual
00809-0100-4308
Rosemount 3308 Series