Siemens SIMATIC S7-400 Hardware And Installation Manual page 276

Glossary
BIOS Basic Input Output System
BIOS is understood to mean the part of the software which creates the
link between hardware and the operating system, for example,
MS-DOS. This software is stored in an EPROM.
Examples of important sections are the loader for the operating
system, the (hardware) setup for defining the hardware configuration
and for setting the time.
Bit Memory (M) A memory area in the system memory of a SIMATIC CPU. This area
can be accessed using write or read access (bit, byte, word, and
double word). The bit memory area can be used by the user to store
intermediate results. It can be accessed bit by bit, byte by byte, word
by word, or double word by double word.
Building Ground The connection between data processing equipment and ground,
whereby no unacceptable functional interference to data processing
equipment is caused by external effects, such as interference caused
by power systems. The connection must be in the form of a low-noise
ground.
Bus A bus is a transfer medium which interconnects several nodes. Data
transmissions can be serial or parallel over electical conductors or
fiber-optic cables.
C
Chassis Ground The chassis ground comprises all interconnected inactive parts of an
apparatus, which even in case of a fault cannot take dangerous touch
voltages.
Communications Communications processors are modules for point-to-point and bus
Processor
connections.
Compress The PG online function "Compress" is used to shift all valid blocks in
the RAM of the CPU evenly and without any gaps to the beginning of
the user memory. All gaps caused by deleting or correcting blocks are
thus removed.
The configuration is the selection and putting together of the individual
Configuration
components of a programmable logic controller (PLC).
Glossary-2
www.gkbpx.com
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01