Emerson Rosemount OCX 8800, Instruction Manual

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Instruction Manual
IM-106-880C, OI
Section 7: Foundation
Fieldbus
April 2017
Arithmetic (ARTHM) Function
Block
14
9
Mode sheds from RCAS
to AUTO
Mode sheds from
ROUT to MAN
Process and/or block
alarms
will not work
1. Remote Cascade Value
2. Shed Timer
1. Remote output value
2. Shed timer
1. Features
2. Notification
3. Status Options
1. Host system is not writing RCAS_IN with a quality and status of
“good cascade” within shed time (see 2 below).
2. The mode shed timer, SHED_RCAS in the resource block is set too
low. Increase the value.
1. Host system is not writing ROUT_IN with a quality and status of
“good cascade” within shed time (see 2 below).
2. The mode shed timer, SHED_RCAS, in the resource block is set
too low. Increase the value.
1. FEATURES_SEL does not have Alerts enabled. Enable the Alerts
bit.
2. LIM_NOTIFY is not high enough. Set equal to MAX_NOTIFY.
3. STATUS_OPTS has Propagate Fault Forward bit set. This should be
cleared to cause an alarm to occur.
7.13 Arithmetic (ARTHM) Function Block
Figure 7-25 Arithmetic (ARTHM) Function Block
IN
IN_LO
IN_1
IN_2
IN_3
OUT
The Arithmetic function block 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.
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.
Symptom Possible Causes Corrective Action
ARTHM
3
9
9
3
0
0
1
8