User guide

54 MDX-ETHERNET User Guide
www.leroy-somer.com Issue : a
15 Glossary of terms
Address : This is the unique network identification given to a networked device to allow
communication on a network. When a device sends or receives data the address is
used to determine the source and the destination of the message.
Auto-crossover detection : A method used to automatically detect if a crossover or
non-crossover network cable is connected.
ADU : Application Data Unit. The complete Modbus message frame (ADU) consists of
the Modbus Application Protocol (MBAP) and Protocol Data Unit (PDU).
Bit : A binary digit, this may have the value of 1 or 0.
Byte : A collection of 8 binary digits that collectively store a value. This may be signed
or unsigned.
Casting : The process of changing between data sizes without changing the value
represented, e.g. changing from 16-bit to 32-bit.
Compression : By default MDX-ETHERNET transmits values as 32-bits on the
network. It is possible by using data compression to reduce the number of bits
transmitted when sending 16-bit (or smaller) values on the network to 16-bit (32-bit
values will still be transmitted as 32-bit values). This has the advantage of reducing the
volume of traffic on the network.
Control word : A collection of binary digits that are used to control the drive. Features
typically include directional controls, run controls and other similar functions.
Data rate : Determines the communication speed of the network, the higher the value
the more data can be sent across the network in the same time period.
Device : A piece of equipment connected to a network, this may be any type of
equipment including repeaters, hubs, masters or slaves.
DNS : Domain Name Server. This is a server that is used to convert a URL such as
"www.leroy-somer.com" to an IP address such as 129.254.254.106.
Double word : A 32 bit word, this may be signed or unsigned.
DHCP : Dynamic Host Configuration Protocol. This is a method of allocating IP settings
of a node from a central server.
Ethernet address : See MAC address.
Explicit data : See Non-cyclic data.
Firewall : A computer or piece of software that restricts connections between different
ports. This can be useful when restricting data flow between two network segments.
FTP : File Transfer Protocol. Used for transferring files.