Emerson Rosemount OCX 8800, Instruction Manual

Page: 184 / 306

Section 7: Foundation
Fieldbus
April 2017
Instruction Manual
IM-106-880C, OI
15
8
Input Selector (ISEL) Function
Block
7.15 Input Selector (ISEL) Function Block
Figure 7-29 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 7-29 illustrates the internal components of the ISEL block. Table 7-35 lists the ISEL
block parameters and their descriptions, units of measure, and index numbers.
Table 7-35 Input Selector Function Block System Parameters
Index
Number
Units Description
ALERT_KEY 4 None The identification number of the plant unit. This information may be used in
the host for sorting alarms, etc.
BLOCK_ALM 24 None The block alarm is used for all configuration, hardw are, connection failure, or
system problems in the block. The cause of the alert is entered in the subcode
field. The first alert to become active will set the Active status in the Status
parameter. As soon as the Unreported status is cleared by the alert reporting
task, another block alert may be reported without clearing the Active status, if
the subcode has changed.
BLOCK_ERR 6 None This parameter reflects the error status associated w ith the hardw are or
software components associated with a block. It is a bit string, so that multiple
errors may be shown.
DISABLE_1 15 None A Connection from another block that disables the associated input fromthe
selection.