Emerson Fisher FIELDVUE DVC6000f, Инструкция по эксплуатации, Страница: 163 / 384

ISEL Function Block
December 2009 4-103
FIELDBUS_56A
SELECTED
OUT
IN_1
IN_2
IN_3
IN_4
DISABLE_5
DISABLE_6
DISABLE_7
DISABLE_8
OP_SELECT
IN (1
−
8)
= Input used in the selection algorithm.
DISABLE (1
−
8) = Discrete input used to enable or disable
the associated input channel.
OP_SELECT
= Input used to override algorithm.
.
SELECTED
=
The selected channel number.
OUT
=
The block output and status.
OUT_D
= Discrete output that signals
IN_5
IN_6
IN_7
IN_8
ISEL
OUT_D
DISABLE_1
DISABLE_2
DISABLE_3
DISABLE_4
a selected alarm condition.
Input Selector (ISEL) Function Block
Overview
The Input Selector (ISEL) function block can be used
to select the first good, maximum, minimum, average,
or hot backup from as many as eight 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 4-14
illustrates the internal components of the ISEL function
block. Table 4-39 lists the ISEL block parameters, their
index numbers, and descriptions.
Modes
The ISEL function block supports three modes of
operation as defined by the MODE_BLK [5]
parameter:
Manual (Man)—The block output (OUT [7]) may
be entered manually.
Automatic (Auto)—OUT [7] reflects the
selected input value.
Out of Service (OOS)—The block is not
processed. The BLOCK_ERR [6] parameter shows
Out of Service. In this mode, you can make changes
to all configurable parameters. The target mode of a
block may be restricted to one or more of the
supported modes.
The Input Selector block Actual mode will be Out of
Service if any of the following are true:
The Actual mode of the resource block is not
Auto
The Input Selector block Target mode is Out of
Service
The Input Selector block Target mode is Auto,
OP_SELECT [22] is not being used, and
SELECT_TYPE [19] is 0. In this case, the
BLOCK_ERR [6] parameter shows a Block
Configuration Error.
The Input Selector block Actual mode will be Manual if
all of the above is not true and the Target mode is
Manual.
Status Handling
Quality Use and Propagation
In Auto mode, OUT [7] reflects the value and status of
the selected input based on the following criteria:
A bad or disabled input is never used by any of
the selection algorithms
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