Siemens v1.0 Wartungshandbuch PDF herunterladen (Seite 198)

Glossary

STEP 7 Basic V10.5

198 Getting Started, 12/2009, A5E02651459-01

Configuring

"Configuring" is understood to mean arranging, setting and networking devices and modules

within the device or network view. Racks are represented symbolically. Just like "real" racks,

they allow you to plug in a defined number of modules.

Contact

You can use contacts to create or interrupt a current-carrying connection between two

elements. The current is relayed from left to right. You can use contacts to query the signal

state or the value of an operand and control it depending on the result of the current flow.

Control

A control is a process in which the result (output variable) influences a controlled variable by

means of a feeback loop.

CPU

The user program is stored and executed in the central processing unit (CPU) of an

automation system. It contains the operating system, processing unit, and communication

interfaces.

CPU operating system

The operating system organizes all functions and sequences of the CPU that are not

associated with a specific control task.

Cycle time

The cycle time is the time that the CPU requires to execute the user program once.

Cyclic interrupt

Cyclic interrupt OBs serve to start program in periodic time intervals independently of the

cyclic program execution. The start times of a cyclic interrupt OB are specified using the time

base and the phase offset.

Data block (DB)

Block in the user program that is used for storing values or character strings. There are

global data blocks that can be accessed by all code blocks and instance data blocks that are

assigned to a specific FB call.

Data type

Specifies how the value of a tag or constant is to be used in the user program. A tag of the

BOOL data type can, for example, only take the value 1 or 0.

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