Siemens Simatic S7-200 System Manual page 284

Instruction Set
Convergence Control
A similar situation arises when two or more streams of sequential states must be merged into
a single stream. When multiple streams merge into a single stream, they are said to
converge. When streams converge, all incoming streams must be complete before the next
state is executed. Figure 10-42 depicts the convergence of two control streams.
Figure 10-42
10-96
State L
State N
Convergence of Control Streams
State M
Transition Condition
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02