Programming Actions and Conditions
S7-GRAPH for S7 300/400 Programming Sequential Control Systems
7-2
C79000-G7076-C526-01
7.1 Actions
In the steps, you program actions that, for example, control the inputs, outputs and
memory bits, activate or deactivate the steps of the sequencer or call blocks. This
means that actions contain instructions for process control. These actions are
executed in order from "top" to "bottom" when the step is active.
You program the step contents in the action table at the single page or single step
display level.
Components of an Action
An action consists of the following:
(1): An optional event (for example S1) and an instruction (for example N) and
(2): An address (for example M4.3) or an assignment (for example A:=B+C).
N
S1 N
M 4.2
M 4.3
S4
S0 R
Q 4.4
Step is active
Order of
execution
Step4
Step4
1
2
Categories of Actions
Actions are divided into the following categories:
•
Standard
actions
-
With and without interlock
•
Event-dependent
actions
-
With and without interlock
-
To activate and deactivate steps
•
Counters, timers and arithmetic in actions
Empty Steps (Steps Without Actions)
Steps that do not contain programmed actions are empty steps. An empty step
behaves like an active step. The following transition becomes valid.