Programming Actions and Conditions
S7-GRAPH for S7 300/400 Programming Sequential Control Systems
7-4 C79000-G7076-C526-01
Time Constant
All actions that contain the instructions D or L require a time to be specified. Times
are programmed as constants with the syntax T#<const> and can be combined as
required.
<const>= nD (n days), nH (n hours), nM (n minutes), nS (n seconds),
nMS (n milliseconds), where n = a number (integer)
Example: T#2D3H: time constant = 2 days and 3 hours
Example: Action Table with Standard Actions
NA1.0
T#1M20S
S4
D
A1.1
Step4
Step4
1
2
(1): As long as the step is active, the signal at output Q1.0 is set to 1.
(2): 1 minute and 20 seconds after step activation and providing the step is still
active, the signal at output Q1.1 is set to 1. If the step is no longer active, the signal
at Q1.1 is 0.
7.3 Event-Dependent Actions
Events
An action can be logically combined with an event. An event is the change in the
signal state of a step, a supervision or an interlock or the acknowledgment of a
message or a registration is set.
If an action is logically combined with an event, the signal state of the event is
recognized by edge detection. This means that the instructions can only be
executed in the cycle in which the event took place.
Events and Signal Evaluation
Step
•
S1: Step becomes active
•
S0: Step is deactivated
1
0
S1
S0
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