Echelon i.LON 100 e2 Internet Server - Manual (Page 202)

i. LON 100 Internet Server Programmer’s Reference 13-9
Identifier Description
FN_LT Less than. Returns True if the value of the input data point is less than that of the
compare data point.
FN_GE Greater than or equal to. Returns True if the value of the input data point is
greater than or equal to that of the compare data point.
FN_LE Less than or equal to. Returns True if the value of the input data point is less than
or equal to that of the compare data point.
FN_EQ Equal. Returns True if the value of the input data point is equal to that of the
compare data point.
FN_NE Not equal. Returns True if the value of the input data point is not equal to that of
the compare data point.
FN_NUL Null. Returns True for all values of the input. Use this if you want the case rules
for a structure to be used each time there is a translation.
13.2.1.2.1.1 Case Rules
You can use case rules to determine the value(s) to be assigned to the output data point(s)
when a Type Translator Rule is used. If the output data point is a structure, you can create
case rules to determine the value that will be assigned to each field in the structure.
For each case rule, you will specify an input data point (and a field name if the input data
point is a structure) to determine the input value. You will also specify a compare value and
a comparison function. The input value will be compared to the compare value using the
specified comparison function. If the result of the comparison is True, the operation defined
by the case rule will be performed. If the result of the comparison is False, the operation will
not be performed and the value of the output data point (or field) will not change.
Consider a Type Translator Rule that converts a SNVT_scene data point into a SNVT_switch
data point. You could create a case rule to assign the value or state fields of the SNVT_switch
data point a value based on scene_number of the SNVT_scene data point. For example, you
could assign the SNVT_switch data point the value 100.0 1 if the scene_number is less than
2, or 0.0 if it is greater than 2. You can create as many case rules as you want per case
structure, so you can plan on as many contingencies as you like.
Each case rule is defined by a <Rule> element. Table 73 describes the properties that should
be filled in within each <Rule> element to define each case rule.
Table 73 Case Rule Properties
Property Description
<UCPTindex> The index number of the case rule.
NOTE: If more than one case rule attempts to assign a value to
the same data point or data point field, the case rule listed last in
the XML file will take precedence.