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Instruction Manual

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Instruction Manual
D103434X012
Blocks
November 2014
141
Arithmetic (ARTH) Function Block
The Arithmetic function block (figure B‐17) provides the ability to configure a range extension function for a primary
input and applies the nine (9) different arithmetic types as compensation to or augmentation of the range extended
input. All operations are selected by parameter and input connection.
Figure B‐17. Arithmetic (ARTH) Function Block
The nine (9) arithmetic functions are Flow Compensation Linear, Flow Compensation Square Root, Flow
Compensation Approximate, BTU Flow, Traditional Multiply and Divide, Average, Summer, Fourth Order Polynomial,
and Simple HTG Compensate Level.
This Arithmetic function block supports mode control (Auto, Manual, Out of Service). There is no standard alarm
detection in this block.
Supported Modes
D Manual (Man)—The block output (OUT) 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 and PV are not updated and the OUT status is set to
Bad: Out of Service. The BLOCK_ERR 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 target mode of a block bay be restricted to one or more of the supported modes.
Alarm Detection
A block alarm will be generated whenever the BLOCK_ERR has an error bit set.
Alarms are grouped into five levels of priority, as shown in table B‐39.
Table B‐39. ARTH Function Block Alarm Priorities
Priority Number Priority Description
(1)
0 The priority of an alarm condition changes to 0 after the condition that caused the alarm is corrected.
1
An alarm condition with a priority of 1 can be recognized by the system. The device monitors the alarm but does not report it
until requested by the host system.
2
An alarm condition with a priority of 2 is reported to the operator, but generally does not require operator attention (such as
diagnostics and system alerts).
3‐7 Alarm conditions of priority 3 to 7 are advisory alarms of increasing priority.
8‐15 Alarm conditions of priority 8 to 15 are critical alarms of increasing priority.
1. The priority classes “advise” and critical” have no relationship to Plant Web Alerts.