Siemens v1.0 Wartungshandbuch PDF herunterladen (Seite 199)

Glossary

STEP 7 Basic V10.5

Getting Started, 12/2009, A5E02651459-01

199

Function block (FB)

According to IEC 1131-3, a function block is a code block with static data. An FB allows you

to pass parameters in the user program. This makes function blocks ideally suited for

programming frequently recurring complex functions, such as closed-loop control or

operating mode selection. Because a function block has a memory (instance data block), its

parameters can be accessed at any time and at any point in the user program.

HMI device

Screen device for displaying the status, progress and operation of the user program.

I/O field

The I/O field is an input and output field that serves for displaying and changing the tag

values.

Input

Memory area in the system memory of the CPU (process image input) or connection to an

input module.

Instance data block

An instance data block stores the formal parameters and static data of function blocks. An

instance data block can be assigned to an FB call or to a call hierarchy of function blocks.

Library

Collection of elements that can be used more than once.

Modify tags

Using the "modify tags" function, you can modify the tags of a user program and assign

permanent values to individual tags at a specified point during execution of the user

program.

Motion control

Software components for drive control. The motion control instructions control the

technological object "Axis". The technological object "Axis" maps an axis in the PLC and is

suited for activating stepper motors and servomotors with pulse interface.

Network

The program of a block is divided into networks. The networks are used to structure

programs.

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