Siemens SIMATIC VS120 Operating Instructions Manual page 196

Glossary
D-sub
Type identification for a connector.
EEPROM
Electrically Erasable Programmable Read Only Memory
EMC
ElectroMagnetic Compatibility
Endian
The data are partly saved with different byte sequences in various computer architectures.
Intel-based computers, for example, save the data differently than the controllers from
Siemens (S7), namely, in reverse sequence. The byte sequence from Intel, termed Little
Endian, is therefore the reverse S7 byte sequence, Big Endian. The following applies to
these two forms:
• Little Endian: The most significant byte is located at the right end of a word.
• Big Endian: The most significant byte is located at the left end of a word.
Ethernet
This is a specific type of local network that works according to a standard defined by Intel,
DEC and Xerox.
FB
Function Block
FDB
A Function Block Diagram is a graphic representation of control functions. Each control task
(function) has a corresponding symbol.
Firmware
Software routines stored in the Read-Only Memory (ROM). Startup routines and local
machine I/O commands are stored in firmware. In terms of user friendliness, firmware takes
an intermediate position between software and hardware.
Gateway
This is a device that is connected to more than one physical TCP/IP network and can
forward or distribute IP packets. A gateway translates various transport protocols or data
formats (for example IPX and IP) and is included in networks mainly because of this
translation function.
Gateways are also known as IP routers.
Glossary-4
Vision Sensor SIMATIC VS120
Operating Instructions, Edition 02/2006, A5E00757507-01