Echelon LonPoint Application and Plug-In - Manual (Page 158)

11-12 Schedule Keeper Utility
To add a parameter constraint, click Add Entry and fill in the Equation and
Error String
columns for the new row. To delete a schedule constraint, select
the constraint to be deleted and click Delete Entry.
System Parameter Constraint Equations
System parameter constraint equations are used to create site-specific
limitations in the way that Schedule Keeper users may modify system
parameters.. If the equation evaluates to FALSE when schedule constraints are
evaluated, the constraint error string will be displayed and the modification will
not be accepted.
Legal equations include:
The comparison equation – if you want to compare one event time to another, all
of the standard comparison operations are available. Examples include:
MaxTemp < 30
The MaxTemp parameter must be less than 30.
MaxTemp > MinTemp + 50
The MaxTemp parameter must exceed the MinTemp parameter by more than 50.
MaxTemp >= MinTemp
The Mextemp parameter must be greater than or equal to the MinTemp
parameter.
MaxTemp != MinTmep
The MaxTemp parameter must not to equal to the MinTemp parameter.
Logical equations - Simple equations may be logically strung together with the
“&” and “|” operators, signifying logical AND and OR, respectively. In general,
this should be avoided, as the same effect can usually be achieved by writing
more constraint equations, and each one can have a more specific error string.
System Parameter Constraint Language
This section specifies the syntax for the system parameter constraint language
and provides some examples of its use. The language is essentially the same as
the time constraint language.
By default the units used in these equations are the ones native to the relevant
network variable types. See Converting to US Units, later in this chapter, for
information on using non-SI units.
The following notation will be used in the examples and grammar:
Operands
c is the value of the named constant c.
For example, space1TempThreshold might be 22.1 degrees C