Siemens SIMATIC S7-1200 - Page 8

Table of contents
S7-1200 Programmable controller
8 System Manual, V4.2, 09/2016, A5E02486680-AK
4.4 Wiring guidelines .................................................................................................................... 76
5 PLC concepts ....................................................................................................................................... 83
5.1 Execution of the user program ............................................................................................... 83
5.1.1 Operating modes of the CPU ................................................................................................. 87
5.1.2 Processing the scan cycle in RUN mode ............................................................................... 91
5.1.3 Organization blocks (OBs) ..................................................................................................... 92
5.1.3.1 Program cycle OB .................................................................................................................. 92
5.1.3.2 Startup OB ............................................................................................................................. 93
5.1.3.3 Time delay interrupt OB ......................................................................................................... 93
5.1.3.4 Cyclic interrupt OB ................................................................................................................. 94
5.1.3.5 Hardware interrupt OB ........................................................................................................... 95
5.1.3.6 Time error interrupt OB .......................................................................................................... 96
5.1.3.7 Diagnostic error interrupt OB ................................................................................................. 97
5.1.3.8 Pull or plug of modules OB .................................................................................................. 100
5.1.3.9 Rack or station failure OB .................................................................................................... 101
5.1.3.10 Time of day OB .................................................................................................................... 102
5.1.3.11 Status OB ............................................................................................................................. 102
5.1.3.12 Update OB ........................................................................................................................... 103
5.1.3.13 Profile OB ............................................................................................................................. 103
5.1.3.14 MC-Servo and MC-Interpolator OB...................................................................................... 103
5.1.3.15 MC-PreServo ....................................................................................................................... 104
5.1.3.16 MC-PostServo ...................................................................................................................... 105
5.1.3.17 Event execution priorities and queuing ................................................................................ 105
5.1.4 Monitoring and configuring the cycle time ........................................................................... 109
5.1.5 CPU memory ........................................................................................................................ 110
5.1.5.1 System and clock memory ................................................................................................... 112
5.1.6 Diagnostics buffer ................................................................................................................ 114
5.1.7 Time of day clock ................................................................................................................. 115
5.1.8 Configuring the outputs on a RUN-to-STOP transition ........................................................ 116
5.2 Data storage, memory areas, I/O and addressing ............................................................... 117
5.2.1 Accessing the data of the S7-1200 ...................................................................................... 117
5.3 Processing of analog values ................................................................................................ 123
5.4 Data types ............................................................................................................................ 125
5.4.1 Bool, Byte, Word, and DWord data types ............................................................................ 126
5.4.2 Integer data types ................................................................................................................ 127
5.4.3 Floating-point real data types ............................................................................................... 127
5.4.4 Time and Date data types .................................................................................................... 128
5.4.5 Character and String data types .......................................................................................... 130
5.4.6
Array data type ..................................................................................................................... 132
5.4.7 Data structure data type ....................................................................................................... 133
5.4.8 PLC data type ...................................................................................................................... 133
5.4.9 Variant pointer data type ...................................................................................................... 134
5.4.10 Accessing a "slice" of a tagged data type ............................................................................ 134
5.4.11 Accessing a tag with an AT overlay ..................................................................................... 135
5.5 Using a memory card ........................................................................................................... 138
5.5.1 Inserting a memory card in the CPU .................................................................................... 139
5.5.2 Configuring the startup parameter of the CPU before copying the project to the
memory card ........................................................................................................................ 142
5.5.3 Transfer card ........................................................................................................................ 142