Analog Input Function Block - Fisher FIELDVUE DVC6200f Instruction Manual

Instruction Manual
D103412X012

Analog Input Function Block

Overview
The Analog Input (AI) function block (figure 4‐23) processes field device measurements and makes them available to
other function blocks. The output value from the AI block is in engineering units and contains a status indicating the
quality of the measurement. The measuring device may have several measurements or derived values available in
different channels. Use the channel number to define the variable that the AI block processes.
Figure 4‐23. Analog Input (AI) Function Block
= THE BLOCK OUTPUT VALUE AND STATUS
OUT
OUT_D = DISCRETE OUTPUT THAT SIGNALS A SELECTED
ALARM CONDITION
The AI block supports alarming, signal scaling, signal filtering, signal status calculation, mode control, and simulation.
In Automatic mode, the block's output parameter (OUT [8]) reflects the process variable (PV [7]) value and status. In
Manual mode, OUT [8] may be set manually. The Manual mode is reflected on the output status. A discrete output
(OUT_D [37]) is provided to indicate whether a selected alarm condition is active. Alarm detection is based on the OUT
[8] value and user specified alarm limits. Figure 4‐24 illustrates the internal components of the AI function block, and
table 4‐57 lists the AI block parameters and their units of measure, descriptions, and index numbers.
Modes
The AI function block supports three modes of operation as defined by the MODE_BLK [5] parameter:
D Manual (Man) The block output (OUT [8]) may be set manually.
D Automatic (Auto) OUT reflects the analog input measurement or the simulated value when simulation is enabled.
D Out of Service (OOS) The block is not processed. FIELD_VAL [19] and PV [7] are not updated and the OUT [8] status
is set to Bad: Out of Service. The BLOCK_ERR [6] parameter shows Out of Service. In this mode, you can make
changes to all configured parameters. The target mode of a block may be restricted to one or more of the
supported modes.
Alarm Detection
A block alarm will be generated whenever the BLOCK_ERR [6] has an error bit set. The types of block errors for the AI
block are defined in table 4‐55.
OUT_D
OUT
Detailed Setup—AI Function Block
July 2013
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