Specifications

• Trending allows you to determine whether a particular variable is

approaching a value of concern. It is like a “predictive” alarm. If the

number you enter in the first edit box is lower than the number you enter

in the second box, the data logger will check for an upward trend.

Likewise, if the number in the first edit box is higher than the number

you enter in the second box, the data logger will check for a downward

trend. The third edit box is used to indicate the maximum period of time

that may elapse before this alarm is no longer valid.

For this type of alarm to be valid, the parameter of interest must pass

through both thresholds within the specified time period. If the

parameter is between the thresholds when the alarm is set, or above the

higher threshold for an upward trend alarm or below the lower threshold

for a downward trend alarm, the alarm will not become active. Please

note that frequent communication with the data logger will cause the

timing function of this alarm type to run long.

For guidance on how to use this alarm, it may be best to consult

historical weather data from WeatherLink plot data (or other sources) to

determine what kind of behavior a parameter exhibits before approaching

a value of concern. Make note of how quickly the value changes over

time before it reaches that value. These changes will govern your

threshold values and time period. Your second threshold probably

should not match this value, but rather be lower than this value for a