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Introduction to STEP 5
The program uses block calls to exit one block and jump to another. You can therefore nest
program, function, and sequence blocks randomly in up to 32 levels (see Section 7.3).
Note
When calculating the nesting depth, note that the system program itself can call an
organization block under certain circumstances (e.g. OB32).
The total nesting depth is the sum of the nesting depths of all programmed organization blocks. If
nesting goes beyond 32 levels, the PLC goes into the "STOP" mode with the error message
"STUEB" (block stack overflow) (see Section 5.1). Figure 7-2 illustrates the nesting principle.
OB1
Level 1
7-6
Level 2
Level 3
Figure 7-2. Nesting
S5-115U Manual
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Level 32
EWA 4NEB 811 6130-02b
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