Rockwell Automation 1732E-OB8M8SR EtherNet/IP Dual Port 8-Point SOE Input and Scheduled Output Modules UM - Manual (Page 17)

Rockwell Automation Publication 1732E-UM003B-EN-E - March 2014 7
Module Overview and Features Chapter 2
If the ring topology is used, the Ring Master (not the 1732E ArmorBlock
EtherNet/IP Dual Port 8-Point Sequence of Events Input or Scheduled Output)
must be designated in the system, and determines the beacon rate and the timeout
period. For more information on topologies, refer to publication
ENET-AP005 .
The 1732E-IB8M8SOER and 1732E-OB8M8SR modules are CIP Sync slave
only devices. There must be another module on the network that functions as a
master clock.
Introduction to CIP Sync CIP is the Common Industrial Protocol that we use to let all
Rockwell Automation products communicate with each other whether it be on a
DeviceNet, ControlNet, and/or an EtherNet network. Since it is an ODVA
standard, other industrial product manufacturers develop products to
communicate via the CIP protocol.
CIP Sync is a CIP implementation of the IEEE 1588 PTP (Precision Time
Protocol) in which devices can bridge the PTP time across backplanes and on to
other networks via EtherNet/IP ports.
What is IEEE 1588 PTP (Precision Time Protocol)?
The IEEE 1588 standard specifies a protocol to synchronize independent clocks
running on separate nodes of a distributed measurement and control system to a
high degree of accuracy and precision. The clocks communicate with each other
over a communication network. In its basic form, the protocol is intended to be
administration free. The protocol generates a master slave relationship among the
clocks in the system. Within a given subnet of a network there will be a single
master clock. All clocks ultimately derive their time from a clock known as the
grandmaster clock. This is called Precision Time Protocol (PTP).
The PTP is a time-transfer protocol defined in the IEEE 1588-2008 standard
that allows precise synchronization of networks, for example, Ethernet. Accuracy
within the nanosecond range can be achieved with this protocol when using
hardware generated synchronization.
IEEE 1588 is designed for local systems requiring very high accuracies beyond
those attainable using Network Time Protocol (NTP). NTP is used to
synchronize the time of a computer client or server to another server or reference
time source, such as a GPS.
CIP Sync Support
CIP Sync supports the IEEE 1588-2008 synchronization standard. In this
architecture, a grandmaster clock provides a master time reference for the system
time. The 1732E-IB8M8SOER, 1732E-OB8M8SR modules are CIP Sync slave