Rockwell Automation 842E CM Integrated Motion Encoder on EtherNet/IP - Manual (Page 8)

8 Rockwell Automation Publication 842E-UM002A-EN-P - November 2013
Preface
Quality of Service (QoS) A function that guarantees a bandwidth relationship between individual applications
or protocols.
Service Data Block The service data block is a lower priority real-time data block associated with a service
message from the controller that is transferred by an Integrated Motion on the
EtherNet/IP network connection on a periodic basis. Service data includes service
request messages to access attributes, run a drive based motion planner, or perform
various drive diagnostics.
Servo drive A drive that produces the winding current for a servo motor. The amplifier converts a
low-level control signal into high voltage and current levels in order to produce torque
in the motor.
Set/Write A Set/Write involves setting an attribute to a specified value from the perspective of
the Controller side of the interface.
Slave (S) Synchronizes the local clock to the Master time. Synchronizes the local clock frequency
to match the Master reference.
Synchronized Synchronized is a condition where the local clock value on the drive is locked onto the
master clock of the distributed System Time. When synchronized, the drive and
controller devices may use time stamps associated with an Integrated Motion on the
EtherNet/IP network connection data.
System Time The absolute time value as defined by CIP Sync in the context of a distributed time
system where all devices have a local clock that is synchronized with a common Master
clock. System Time is a 64-bit integer value in units of nanoseconds or microseconds
with a value of 0 corresponding to an epoch of January 1, 1970.
Time Offset Time offset is the System Time Offset value associated with the Integrated Motion on
the EtherNet/IP network connection data that is associated with the source device. The
System Time Offset is a 64-bit offset value that is added to a device’s local clock to
generate System Time for that device.
Time Stamp Time stamp is a system time stamp value associated with the Integrated Motion on
the EtherNet/IP network connection data that conveys the absolute time when the
associated data was captured, or can be also used to determine when associated data
is to be applied.
Transparent Clock A Transparent Clock improves the accuracy of time synchronization by compensating
for the effect of port to port PTP packet propagation delays.
Variable Frequency Drive
(VFD) Variable Frequency Drive (VFD) is a class of drive products that seek to control the
speed of a motor, typically an induction motor, through a proportional relationship
between drive output voltage and commanded output frequency. Frequency drives
are, therefore, sometimes referred to as Volts/Hertz drives
TIP Not all servo drives support direct frequency control.
Term Definition