Rockwell Automation Logix5000 Controllers Sequential Function Charts Programming Manual - Manual (Page 17)

Design a sequential function chart Chapter 1
• When you first open an SFC routine, it contains an initial step and
transition. Use this step to initialize your process.
The controller executes the initial step in these situations.
• After a project download when the controller goes into Run mode.
• When the controller transitions to Run mode and on power-up (if the
SFC is configured for that).
• When the routine containing the chart is modified online and a reset is
required, and the controller transitions to or from Test mode.
• To identify a step, look for a physical change in your system, such as new
part that is in position, a temperature that is reached, a preset time that is
reached, or a recipe selection that occurs. The step is the actions that take
place before that change.
• Stop refining the steps when they are in meaningful increments. This is an
example.
This organization of steps Is
produce_solution Probably too large
set_mode, close_outlet, set_temperature, open_inlet_a, close_inlet_a,
set_timer, reset_temperature, open_outlet, reset_mode
Probably too small
preset_tank, add_ingredient_a, cook, drain Probably about right
SFC_STEP structure
Each step uses a tag to provide information about the step. Access this information
with either the Step Properties dialog box or the Monitor Tags tab of the Tags
window.
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