Emerson Rosemount OCX 8800, Instruction Manual

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Instruction Manual
IM-106-880C, OI
Section 7: Foundation
Fieldbus
April 2017
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.
Table 7-20 lists the AI block parameters and their units of
measure, descriptions, and index numbers.
Table 7-20 Definitions of Analog Input Function Block System Parameters
ACK_OPTION 23 None Used to set auto acknowledgment of alarms.
ALARM_HYS 24 Percent The amount the alarm value must return within the alarm limit before
the associated active alarm condition clears.
ALARM_SEL 38 None Used to select the process alarm conditions that will cause the OUT_D
parameter to be set.
ALARM_SUM 22 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 be-
come 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.
ALERT_KEY 04 None The identification number of the plant unit. This information may be
used in the host for sorting alarms, etc.
BLOCK_ALM 21 None The block alarm is used for all configuration, hardware, 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 06 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.
CHANNEL 15 None The CHANNEL value is used to select the measurement value. Refer to
the appropriate device manual for information about the specific chan-
nels available in each device.
You must configure the CHANNEL parameter before you can configure
the XD_SCALE parameter.
FIELD_VAL 19 Percent The value and status from the transducer block or from the simulated
input when simulation is enabled.
GRANT_DENY 12 None Options for controlling access of host computers and local control pan-
els to operating, tuning, and alarm parameters of the block. Not used
by device.
HI_ALM 34 None The HI alarm data, which includes a value of the alarm, a timestamp of
occurrence and the state of the alarm.
HI_HI_ALM 33 None The HI HI alarm data, which includes a value of the alarm, a timestamp
of occurrence and the state of the alarm.
Introduction 115
Parameter
Index
Number Units Description