Control Mode Priorities And Indications - Honeywell Series A User Manual

GRANT_DENY.GRANT parameter bits. It is standard Experion system behavior to take
a grant back after an operator changes a mode relative to its mode attribute (MODATTR)
parameter.
The following table shows how control modes are mapped to fieldbus ones.
Control Mode
MAN
AUTO
CAS
NORMAL
BCAS
NONE

Control mode priorities and indications

The following table shows the 2-character and 4-character mode indications to be used in
operating displays and lists the mode priorities based on several interpretations. The
Priority Order interpretation is based on the Out-of-Service mode being serviced over all
others. The Control Order interpretation is based on the traditional control engineer's
concept that Cascade is a higher mode of operation than Automatic, Automatic is a
higher mode of operation than Manual, and so on. The Dominance Order interpretation is
based on Fieldbus Foundation special rules for modes dominating one another. For
example, Out-of-Service dominates over Manual, Manual dominates over Remote Out,
and Remote Out dominates over Remote Cascade. This is relevant, if multiple mode bits
are set in the target (or normal) mode bitstrings.
A block uses the concept of priority to compute an actual mode that is different from the
target mode, and to determine if the particular actual mode allows write access.
Mode
2-Char
R400 Experion PKS Series A Fieldbus Interface Module User's Guide
July 2010
Fieldbus Mode
Man
Auto
Cas
Normal
Error!
Error!
Mode Abbreviation
4-Char
Honeywell
3. Fieldbus Integration With Experion System
3.3. Control Mode Interaction
Comment
When setting as target mode, read
MODE.NORMAL value and write to
MODE.TARGET.
Not used in fieldbus blocks. Attempt to set to
target is illegal.
Not used in fieldbus blocks. Attempt to set to
target is illegal.
Priority Interpretation
Priority Control
Order Order
(8=highest) (8=highest)
Dominance
Order
(6=Highest)
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