Siemens NAN 67 Series Manual de servicio descargar pdf (Pagina 303)

Glossary-9

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

The status word is part of the register of the CPU. It contains status

information and error information which is displayed when specific STEP 7

commands are executed. The status bits can be read and written on by the

user, the error bits can only be read.

A source file programmed in Statement List.

The status bit OS stands for “stored overflow bit of the status word”. An

overflow can take place, for example, after a math operation.

In symbolic addressing the address being processed is designated with a

symbol (as opposed to an absolute address).

A system function is integrated in the CPU and can, if necessary, be called

from the STEP 7 user program.

A system function block is a function block that is integrated in the S7

operating system that you can call from your program if necessary.

A symbol is a name which can be defined by the user subject to syntax

guidelines. After it has been declared (for example, as a variable, data type,

jump label, block etc) the symbol can be used for programming and for

operator interface functions. Example: Address: I 5.0, data type: Bool,

Symbol: momentary contact switch / emergency stop.

A table in which the symbols of addresses for shared data and blocks are

allocated. Examples: Emergency Stop (symbol) -I 1.7 (address) or

closed-loop control (symbol) - SFB24 (block).

User data types are special data structures which you can create yourself and

use in the entire CPU program after they have been defined. They can be

used like elementary or complex data types in the variable declaration of

logic blocks (FCs, FBs, OBs) or as a template for creating data blocks with

the same data structure.

Status Word

STL Source File

Stored Overflow

Bit

Symbolic

Addressing

System Function

(SFC)

System Function

Block (SFB)

Symbol

Symbol Table

User Data Types

(UDTs)

Glossary

1 2 ... 298 299 300 301 302 303 304 305 306 307 308 ... 317 318

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