Siemens SIMATIC S7-400 Installation Manual page 214

Glossary
Functional Grounding
Grounding whose only purpose is to ensure the intended function of the electrical
equipment concerned. Functional grounding short-circuits any noise that might
otherwise have a detrimental effect on the equipment.
Function Block (FB)
According to IEC 61131-3, a function block (FB) is a code block that contains static
data. It is assigned an instance DB as memory. All parameters and static tags
passed to the FB are stored in the instance DB. Its temporary data are stored in the
local data stack.
Data in the instance DB are retentiveAn FB allows parameters to be passed in the
user program. Function blocks are therefore suitable for programming complex
functions, e.g. closed-loop controls, mode selections, which are repeated
frequently
Function Module (FM)
A programmable module which, in contrast to the CPU, has no multipoint interface
and can only be operated as a slave.
G
Global Data Communication
Global data communication is a procedure with which shared data are transferred
between CPUs.
Ground
The conductive mass of the ground whose potential can be assumed to be zero at
any point.
In the vicinity of ground electrodes, the ground may have a potential other than
zero. The term "reference ground" is often used in this situation.
Ground (verb)
To ground means connecting an electrically conductive part via a grounding system
to ground (one or more electrically conductive parts that have good contact with the
soil).
GSD File
The device master file (GSD file) contains all slave-specific data. The format of
GSD files is specified in EN 50170, Volume 2, PROFIBUS.
Glossary-6
Automation System S7-400 Hardware and Installation
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