
10.STEP SEQUENCE FUNCTION B-63983EN/02
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Fig. 10.1.1(b) Module method
Given these conditions, a step sequence method has been created to
describe programs structurally. It is well-suited to the control of entire
processes and provides an easy-to-understand visualized flow of the
process. The step sequence programming features the direct
representation of the control flow on a flow chart, as shown in Fig.
10.1.1(c).
Each block of processing is described as a subprogram, using the
ladder method. The entire program is then created by combining these
subprograms.
Fig. 10.1.1(c) Step sequence method
The step sequence method has the following features:
(1) Increased programming efficiency
· Since the flow of processes can be programmed directly,
simple, correct programming is enabled, reducing the time
required for programming.
· Even for complicated control, programming proceeds from
the main flow to detailed flow in each process, creating a
structured, top-down program, which is easy-to-understand
by persons other than the original creator.
· Structured modules can be used again easily.
CALL
CALL
Subprogram
Subprogram
Transition
Step 1
Step 2
Subprogram of ladder diagram
Drawing flow