Assigning Parameters to and Calling the S7-Graph FB
S7-GRAPH for S7 300/400 Programming Sequential Control Systems
9-10
C79000-G7076-C526-01
9.7
The Modes of the Sequential Control System
By selecting one of the four possible modes, you decide how the sequencer
progresses from step to step. By setting suitable parameters for the S7-Graph FB,
you can select the mode of the sequential control system as required. The
following modes are available:
•
Automatic
mode
:
In the automatic mode, the next step in enabled when a transition is satisfied.
•
Manual
mode:
In contrast to the automatic mode, in the manual mode, the next step in not
enabled when the transition is satisfied. The steps are selected and deselected
manually.
•
Inching mode step to next:
The inching mode corresponds to the automatic mode with an additional step
enabling condition. Not only must the transition be satisfied, but there must also
be a rising edge at the T_PUSH parameter before control passes to the next
step.
•
Automatic or step to next:
In the "automatic or step-by-step" mode, control is passed to the next step when
the transition is satisfied or when there is a rising edge at the T_PUSH
parameter.
Requirements for Operation in Different Modes
Automatic mode is the standard mode for sequencers. It is available and is the
default for all parameter sets of the S7-Graph FB.
To be able to select a different mode, you must compile the S7-Graph FB with the
standard, maximum or definable parameter set.
Selecting Modes
You select one of the four modes using the input parameters of the FB. Apply a
rising edge to one of the following parameters to activate the corresponding mode.
•
SW_AUTO
(Automatic
Mode)
•
SW_MAN (Manual Mode)
•
SW_TAP (Inching Mode)
•
SW_TOP (Automatic or Switch to next)