Owner's manual

Section
8-1
8 Input Selector (ISEL)
Function Block
The Input Selector (ISEL) function block can be used to select the first
good, Hot Backup, maximum, minimum, or average of as many as four
input values and place it at the output. The block supports signal status
propagation. There is no process alarm detection in the Input Selector
function block. Figure 8-1 illustrates the internal components of the
ISEL function block. Table 8-1 lists the ISEL block parameters and
their descriptions, units of measure, and index numbers.
fieldbus-fbus_40a
SELECTED
OUT
IN_1
IN_2
IN_3
IN_4
DISABLE_1
DISABLE_2
DISABLE_3
DISABLE_4
OP_SELECT
ISEL
IN (1-4) = Input used in the selection algorithm.
DISABLE (1-4) = Discrete input used to enable or disable
the associated input channel.
OP_SELECT = Input used to override algorithm.
TRK_VAL = The value after scaling applied to OUT
in Local Override mode.
SELECTED = The selected channel number.
OUT = The block output and status.
TABLE 8-1. Input Selector Function Block System Parameters
Parameter
Index
Number
Description
ST_REV 01 The revision level of the static data associated with the function block. The revision value
will be incremented each time a static parameter value in the block is changed.
TAG_DESC 02 The user description of the intended application of the block.
STRATEGY 03 The strategy field can be used to identify grouping of blocks. This data is not checked or
processed by the block.
ALERT_KEY 04 The identification number of the plant unit. This information may be used in the host for
sorting alarms, etc.
MODE_BLK 05 The actual, target, permitted, and normal modes of the block.
Target: The mode to “go to”
Actual: The mode the “block is currently in”
Permitted: Allowed modes that target may take on
Normal: Most common mode for target