Rockwell Automation MMCL Using the Mining, Mineral, and Cement Library (MMCL) in RSLogix 5000 Appli - Manual (Page 16)

Publication RA-UM002B-EN-P - November 2010
16 Developing an RSLogix 5000 Application
Grouping of Programs
For a clear program structure, it is recommended, to specify separate programs
for each Control Group. To start a new program, right-click the MainProgram
and select New Routine.
A Control Group may also be split functionally, using a ladder program, for
motor control I/O status and interlocking, a Sequential Function Chart
(SFC), for module start and stop sequences (including structured text) and a
Function Block Diagram (FBD), for analog process controls. The different
methods are supported by the corresponding RSLogix 5000 Editors. The
MMCL Add-On Instructions are available for Ladder, Function Block and
Structured Text.
For automatic start and stop sequences, use an SFC, especially if devices
must be stopped individually, rather than by a common shutdown command.
If, however, a common shutdown or delay time is suitable, then an SFC is not
required and a group can be stopped by the Control Group's built-in
stop-delay timer, using standard ladder interlocking only.
For analog signal processing, use a FBD, which is more comprehensive,
showing the signal flow better than a Ladder diagram.