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Reference Manual
00809-0100-4697, Rev EA
October 2011
D-9
Rosemount 848T
MULTIPLE ANALOG
INPUT (MAI) FUNCTION
BLOCK
The Multiple Analog Input (MAI) function block has the ability to process up to
eight field device measurements and make them available to other function
blocks. The output values from the MAI block are in engineering units and
contain 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 numbers to define the variables that the
MAI block processes.
The MAI block supports signal scaling, signal filtering, signal status
calculation, mode control, and simulation. In Automatic mode, the block’s
output parameters (OUT_1 to OUT_8) reflects the process variable (PV)
values and status. In Manual mode, OUT may be set manually. The Manual
mode is reflected on the output status. Table D-4 lists the MAI block
parameters and their units of measure, descriptions, and index numbers. The
block execution time is 30 ms.
Out1 = The block output value and status
for the first channel.
OUT_1
MAI
OUT_2
OUT_3
OUT_4
OUT_5
OUT_6
OUT_7
OUT_8
Table D-4. Multiple Analog Input Function Block Parameters
Number Parameter Units Description
1 ST_REV None The revision level of the static data associated with the input selector block. The
revision value will be incremented each time a static parameter value in the block is
changed.
2 TAG_DESC None The user description of the intended application of the block.
3 STRATEGY None The strategy field can be used to identify grouping of blocks. This data is not
checked or processed by the block.
4 ALERT_KEY None The identification number of the plant unit. This information may be used in the host
for sorting alarms, etc.
5 MODE_BLK None The actual, target, permitted, and normal modes of the block.
Actual: The mode the “block is currently in”
Target: The mode to “go to”
Permitted: Allowed modes that target may take on
Normal: Most common mode for target
6 BLOCK_ERR None This parameter reflects the error status associated with the hardware or software
components associated with a block. It is a bit string, so that multiple errors may be
shown.
7 CHANNEL None Allows for custom channel setting. Valid values include:
0: Unitialized
1: Channels 1 to 8 (index values 27 to 34 can only be set to their corresponding
channel number, i.e. CHANNEL_X=X)
2: Custom settings (index values 27 to 34 can be configured for any valid channel
as defined by the DD)
8, 9, 10, 11,
12, 13, 14,
15
OUT (1, 2, 3, 4, 5,
6, 7, 8)
EU of OUT_SCALE The block output value and status
16 UPDATE_EVT None This alert is generated by any change to the static data
17 BLOCK_ALM None The block alarm is used for all configuration, hardware connection feature, 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
may be reported without clearing the Active status, if the subcode has changed.
18 SIMULATE None A group of data that contains the current sensor transducer value and status, and
the enable/disable bit.