Emerson Oxymitter 5000 Instruction Manual page 129

Appendix
B
TABLE B-1. Definitions of Analog Input
Function Block System Parameters.
Parameter Index
Number
ACK_OPTION 23
ALARM_HYS 24
ALARM_SEL 38
ALARM_SUM 22
ALERT_KEY 04
Analog Input (AI)
Function Block
OUT
OUT_D
The Analog Input (AI) function block 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.
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) reflects the process variable (PV)
value and status. In Manual mode, OUT may be set manually. The
Manual mode is reflected on the output status. A discrete output
(OUT_D) is provided to indicate whether a selected alarm condition is
active. Alarm detection is based on the OUT value and user specified
alarm limits. Figure B-1 on page B-4 illustrates the internal
components of the AI function block, and Table B-1 lists the AI block
parameters and their units of measure, descriptions, and
index numbers.
Units
None Used to set auto acknowledgment of alarms.
Percent The amount the alarm value must return within the alarm limit before the associated active
alarm condition clears.
None Used to select the process alarm conditions that will cause the OUT_D parameter to be set.
None The summary alarm is used for all process alarms 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.
None The identification number of the plant unit. This information may be used in the host for
sorting alarms, etc.
OUT_D
AI
OUT
= The block output value and status
= Discrete output that signals a selected
alarm condition
Description
B
B-1