2 comparison functions – Echelon i.LON 100 e2 Internet Server User Manual
Page 101
i.
LON 100 Internet Server Programmer’s Reference
Identifier Notes
PR_10
HVAC Critical Equipment RTN, Fire RTN (Display)
PR_16
HVAC RTN (lowest priority)
PR_NUL
Value not available
7.2.1.2.2 Comparison Functions
Table 24 describes the comparison functions an Alarm Generator can use when comparing
the values of the input and compare data points. You can select a comparison function for the
Alarm Generator by filling in the
reference each comparison function with the identifier strings listed in Table 24.
Table 24 Comparison Functions
Identifier Description
FN_GT
Greater than. In this case, an alarm will be generated if the input value is
greater than the compare value.
FN_LT
Less than. In this case, an alarm will be generated if the input value is less
than the compare value.
FN_GE
Greater than or equal. In this case, an alarm will be generated if the input
value is greater than or equal to the compare value.
FN_LE
Less than or equal. In this case, an alarm will be generated if the input value
is less than or equal to the compare value.
FN_EQ
Equal. In this case, an alarm will be generated if the input value is equal to
the compare value.
FN_NE
Not equal. In this case, an alarm will be generated if the input value is not
equal to the compare value.
FN_LIMIT
Compare against the limits defined by the high and low limit offset fields.
For more information on how these limits are used, see Hysteresis Levels and
Offset Limits on page 7-13.
Different comparison functions should be used for different data point types, depending on
the
and the comparison functions you can use with them.
Table 25 Base Types and Comparison Functions
Base Type
Valid
BT_UNKNOWN, BT_ENUM, BT_ARRAY,
BT_STRUCT, BT_UNION, BT_BITFIELD
FN_EQ, FN_NE
BT_SIGNED_CHAR, BT_UNSIGNED_CHAR,
BT_SIGNED_SHORT, BT_UNSIGNED_SHORT,
BT_SIGNED_LONG, BT_UNSIGNED_LONG,
BT_FLOAT, BT_SIGNED_QUAD,
BT_UNSIGNED_QUAD, BT_DOUBLE
FN_GT, FN_LT, FN_GE,
FN_LE, FN_EQ, FN_NE,
FN_LIMIT
7-12