Rockwell Automation 842E CM Integrated Motion Encoder on EtherNet/IP - Manual (Page 7)

Rockwell Automation Publication 842E-UM002A-EN-P - November 2013 7
Preface
Terminology
Term Definition
Axis An axis is a logical element of a motion control system that exhibits some form of
movement. Axes can be rotary or linear, physical or virtual, controlled or simply
observed.
Boundary Clock A clock that has multiple PTP ports in a domain and maintains the time scale used in
the domain. It may serve as the source of time, for example, a Master clock, and may
synchronize to another clock, thus being a Slave clock.
CIP Common Industrial Protocol.
CIP Sync CIP Sync defines extensions to CIP Common objects and device profiles to support time
synchronization over CIP Networks. CIP Sync is an implementation of the IEEE 1588
standard.
Coordinated System Time
(CST) A backplane clock propagated between all modules on the ControlLogix backplane.
Coordinated Universal
Time (UTC) The time standard for
civil time, representing time at the Prime Meridian. The time
does not include time zone or daylight savings time offsets. System Time is based on
UTC.
Device Level Ring (DLR) A DLR network is a single-fault tolerant ring network intended for the interconnection
of automation devices.
Get/Read A Get/Read involves retrieving an attribute value from the perspective of Controller
side of the interface.
GPS Global Positioning System, a time source reference.
Grandmaster Clock (GM) Within a domain, a clock that is the ultimate source of time for clock synchronization
by using the CIP Sync protocol.
Greenwich Mean Time,
(GMT) Greenwich Mean Time is the mean solar time of the longitude (0°) of the former Royal
Observatory at Greenwich, England, or Greenwich meridian.
UTC replaced GMT as the basis for the main reference time scale or civil time in various
regions on January 1, 1970.
Integrated Motion on the
Ethernet/ IP Network Defines extensions to CIP Common objects and device profiles to support motion
control over CIP networks.
Integrated Motion on the
Ethernet/ IP network I/O
Connection The I/O connection is the periodic bidirectional, Class 1, CIP connection between a
controller and a drive that is defined as part of the Integrated Motion on the
EtherNet/IP network standard.
Integrated Motion on the
EtherNet/IP Network Drive Refers to any drive device that complies with the CIP Motion standard.
Master Clock (M) In the context of a single CIP Sync communication path, a clock that is the source of
time to which all other clocks on that path synchronize.
The Master clock may not be the Grandmaster. The Master clock is the reference clock
for the local subnet.
Motion Motion refers to any aspect of the dynamics of an axis. In the context of this document,
it is not limited to servo drives but encompasses all forms of drive based motor control.
Open Loop Open loop is a method of control where there is no application of feedback to force the
actual motor dynamics to match the commanded dynamics. Examples of open loop
control are stepper drives and variable frequency drives.
Ordinary Clock A clock that has a single PTP port in a domain and maintains the time scale used in the
domain. It may serve as the source of time, for example, a Master clock, and may
synchronize to another clock, thus being a Slave clock
Precision Time Protocol
(PTP) A high-precision time synchronization protocol for networked measurement and
control systems, defined by the IEEE 1588 standard.