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F
Fieldbus
™
OUNDATION
December 2022
Priority
number
1
2
3-7
8-15
8.10.4
Block execution
The arithmetic function block provides range extension and compensation
through nine arithmetic types.
There are two inputs (IN and IN_LO) used in calculating PV. PV is then combined
with up to three inputs (IN_1, IN_2, and IN_3) through the user selected
compensation function (ARITH_TYPE) to calculate the value of func. A gain is
applied to func., and then a bias is added to get the value PRE_OUT. In AUTO,
PRE_OUT is used for OUT.
Range extension and calculation of PV
When both IN and IN_LO are usable, the following formula is applied to calculate
range extension for PV:
PV = G * IN + (1-G) * IN_LO
(G has a range from 0 to 1, for IN from RANGE_LO to RANGE_HI.)
8.10.5
Compensation input calculations
For each of the inputs IN_1, IN_3, and IN_4, there is a gain and a bias. The
compensation terms (t) are calculated as follows:
•
When IN_(k) is usable: t(k) = GAIN_IN(k) * (BIAS_IN(k) + IN_(k))
•
When IN_(k) is not usable, then t(k) gets the value of the last t(k) computed with
a usable input.
Status handling
•
IN_x Use Bad
•
IN_x Use Uncertain
•
IN_LO Use Uncertain
•
IN Use Uncertain
200
Priority description
An alarm condition with a priority of
is not reported to the operator.
An alarm condition with a priority of
does not require operator attention (such as diagnostics and system
alerts).
Alarm conditions of priority
increasing priority.
Alarm conditions of priority
priority.
is recognized by the system, but
1
is reported to the operator, but
2
through
are advisory alarms of
3
7
to
are critical alarms of increasing
8
15
Emerson.com/Rosemount
Manual
00809-0500-4880
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