Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 65)

Publication 1757-UM006A-EN-P - May 2002
Integrating Fieldbus into Rockwell Automation Logix System 2-21
While every block type or block instance does not need to support all
eight modes, all eight indicator bits are present in the database. The
mode bit assignments are listed in Table 2.F.
Rotary Switch Model versus Toggle Switch Model
The Fieldbus Foundation supports both the Rotary Switch and the
Toggle Switch models of mode operation. The Rotary Switch model
supports only one mode request at a time. For example, an operator
can request OOS, Man, Auto, Cas, RCas, or ROut. It has no memory of
previous target modes.
The Toggle Switch model supports more than one mode request at a
time. For example, an operator can request Manual override of
Cascade, Manual override of Remote Cascade, and so on.
ProcessLogix supports the Rotary Switch model as well as the
following two instances of the Toggle Switch model.
• An operator may request the Cas mode at the same time the
RCas mode is requested.
• An operator may request the Cas mode at the same time the
ROut mode is requested.
Table 2.F Mode Bit Assignments
Bit = Mode
0 (LSB) = Remote Output (ROut)
1 = Remote Cascade (RCas)
2 = Cascade (Cas)
3 = Automatic (Auto)
4 = Manual (Man)
5 = Local Override (LO)
6 = Initialization Manual (IMan)
7 (MSB) = Out of Service (OOS)