Specifications

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• Minus or “Difference” alarm allows you to compare the difference
between two like variables. For this check type, the two variables must
be measured in the same units of measure in order to be compared. If
this check type is selected, the software will use the parameter pick list
on the row below for the second of the two like variables to indicate.
Enter a positive difference you want to compare in the available edit box
on the second of the two lines (this software will only allow you to enter
a positive difference). Select whether you want to check a “Greater Than
or =” or “Less Than or =” difference. Make sure the equation you create
results in the check that you want. Some examples are provided below:
1. A user wants to activate a fan to bring in cooler outside air to
passively cool their house. This affect only works if the temperature
outside is 5°F lower than the inside temperatures. Additionally, you
don’t want to cool your house if the inside temperature is 70°F or
lower. This can be expressed as:
“IF Inside Temperature Minus Outside Temperature IS Greater Than
or = 5.0°F. AND Inside Temperature IS Greater Than or = 70°F
DONE.”
2. A user wants to activate their sprinkler system when the Daily ET
exceeds the Daily Rainfall by 0.05”:
“IF Daily ET Minus Daily Rain IS Greater Than or = 0.05 DONE”.
3. A user wants to activate environmental controls whenever the
temperature outside differs from the inside temperature by 20°F or
more. Whether it is hotter or colder outside does not matter, but if