184 Rockwell Automation Publication 750COM-UM009A-EN-P - May 2017
Glossary
Hardware Address Each Ethernet device has a unique hardware address (sometimes called a MAC
address) that is 48-bits. The address appears as six digits that are separated by
colons (for example, xx:xx:xx:xx:xx:xx). Each digit has a value from 0 to 255
(0x00 and 0xFF). This address is assigned in the hardware and cannot be
changed. It is required to identify the device if you are using a BOOTP or
DHCP server.
HIM (Human Interface Module) A device that can be used to configure and control a drive. The PowerFlex 20-
HIM-A6 or 20-HIM-C6S HIM can be used to configure PowerFlex 755T
drives and their connected peripherals.
Hold Last When communication is disrupted (for example, a cable is disconnected), the
interface and its connected drive can respond by holding last. Hold last results
in the drive that is receiving the last data that is received via the network
connection before the disruption. If the drive was running and was using the
reference from the interface, it continues to run at the same reference.
Idle Action An idle action determines how the interface and connected drive act when the
controller is switched out of run mode.
IGMP (Internet Group
Management Protocol)
A communication protocol that is used by hosts and adjacent routers on
networks to establish multicast group memberships. IGMP is a part of IP
multicast.
IGMP Snooping The process of listening to Internet Group Management Protocol (IGMP)
network traffic. The feature allows a network switch to listen in on the IGMP
conversation between hosts and routers. By listening to these conversations, the
switch maintains a map of which links need which IP multicast streams.
I/O Data I/O data, sometimes called ‘implicit messages’ or ‘input/output’, is time-critical
data such as a logic command and reference. The terms ‘input’ and ‘output’ are
defined from the controller’s point of view. The output is produced by the
controller and consumed by the interface. The input is produced by the
interface and consumed by the controller. The terms 'To Net' and 'From Net'
used in drive parameters are defined from the drives point of view. 'To Net' is
produced by the drive and consumed by the controller. 'From Net' is produced
by the controller and consumed by the drive.
IP Addresses A unique IP address identifies each node on an EtherNet/IP network. An IP
address consists of 32-bits that are divided into four segments of 1-byte each. It
appears as four decimal integers that are separated by periods
(xxx.xxx.xxx.xxx). Each ‘xxx’ can have a decimal value from 0 to 255. For
example, an IP address could be 192.168.0.1.
An IP address has two parts: a network ID and a host ID. The class of network
determines the format of the address.
01 7 15 23 31
Class A 0 Network ID Host ID
01 7 15 23 31
Class B 1 0 Network ID Host ID
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