Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 64)

Publication 1757-UM006A-EN-P - May 2002
2-20 Integrating Fieldbus into Rockwell Automation Logix System
Control Mode Priorities and Indications
Table 2.E 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 Foundation Fieldbus
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 than the target mode, and to determine if the particular
actual mode allows write access.
Table 2.E 2-character and 4-character mode indications
Mode Mode Abbreviation Priority Interpretation
2-Character 4-Character Priority Order
(8=highest) Control Order
(8=highest) Dominance Order
(6=Highest)
Out-of-Service OS OOS 8 1 6
Initialization Manual IM IMan 7 2 —
Local Override LO LO 6 3 —
Manual M Man 5 4 5
Auto A Auto 4 5 1
Cascade C Cas 3 6 2
Remote Cascade RC RCas 2 7 3
Remote Output RO ROut 1 8 4
TIP The ProcessLogix software installation wizard for
Server includes a dialog box for choosing the desired
mode acronyms. Select the Fieldbus acronyms radio
button to use the mode abbreviations listed above in
the Station displays.