Rockwell Automation Logix5000 Logix5000 Controllers Quick Start - Manual (Page 46)

46 Publication 1756-QS001E-EN-P - October 2009
Chapter 2 Organize a Project
Divide Each Routine Into More Meaningful Increments
If a routine uses this
language Then Example
Ladder logic
Structured text
Break up large routines into several
smaller routines To continuously execute several
complex boolean operations…
…create a separate routine for each
operation.
Function block diagram
(FBD) To control 4 valves, where each valve
requires feedback that it is in its
commanded position…
…make a separate sheet for each
valve.
Sequential function chart
(SFC) To perform the following sequence:
1. Fill a tank.
2. Mix the ingredients in the
tank.
3. Empty the tank…
…make each section (fill, mix, empty)
a separate step.
routine
routine
Within the FBD routine, make
a sheet for each functional
loop for a device, such as a
motor or valve. sheet
routine
step
step
step
Break the SFC into steps.