Technical data

List of Figures

Fig. 1-1 Tasks of the system program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 8

Fig. 1-2 Structure of a STEP 5 user program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 11

Fig. 2-1 Methods of representation in the STEP 5 programming language . . . . . . . . . . . . . . . . . . 2 - 5

Fig. 2-2 Example of block storage in the user memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 16

Fig. 2-3 Block calls that enable processing of a program block . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 18

Fig. 2-4 Structure of a function block (FB/FX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 26

Fig. 2-5 Range of validity of an opened data block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42

Fig. 3-1 Principle of cyclic program execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4

Fig. 3-2 Example of the organization of the user program according

to the program structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 6

Fig. 3-3 Example of the organization of the user program according

to the structure of the controlled system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 7

Fig. 3-4 Nested logic block calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 8

Fig. 3-5 Example of block nesting depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 9

Fig. 3-6 Load and transfer operations in a byte-oriented memory area. . . . . . . . . . . . . . . . . . . . . 3 - 23

Fig. 3-7 Load and transfer operations in a word-oriented memory area . . . . . . . . . . . . . . . . . . . . 3 - 24

Fig. 3-8 Coordination of access to the global memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 73

Fig. 4-1 Front panel of the CPU 928B with display and operating elements . . . . . . . . . . . . . . . . . 4 - 4

Fig. 4-2 Operating states and program processing levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 7

Fig. 4-3: Principle of level change and ISTACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 9

Fig. 4-4 Change of level as a result of a double call error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 11

Fig. 4-5 Double call of error level BCD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 12

Fig. 4-6 Cyclic program execution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 29

List of Tables and Figures

CPU 928B Programming Guide

C79000-T8576-C898-01

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