Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Scaricare il pdf (Pagina 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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Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Pagina 17