Glossary
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
409
Download
In communications, to transfer a data copies from a remote computer to the requesting
computer, for example, to send the operating system from a PC to a controller.
D-sub
Type identification for a connector.
Dynamic Host Configuration Protocol
A TCP/IP service protocol that allows dynamic configurations of host IP addresses for a
certain time and distributes related configuration parameters to authorized network clients.
DHCP provides safe and simple-to-use configuration of TCP/IP networks, prevents address
conflicts and helps to restrict the number of IP addresses required in the network. DHCP
uses a client/server model in which the DHCP server takes over central management of IP
addresses used in the network. Clients with DHCP support can then request and obtain the
lease of an IP address from a DHCP server when the network starts up.
Endian
Data is sometimes saved in a different order in certain computer architectures. Intel-based
computers, for example, save the data differently from the Siemens controllers (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.
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.
Function Block Diagram
Function Block Diagram is a graphic representation of control functions. Each control
function has a corresponding symbol.
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