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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 only devices. There must be another module on the network that will
function as a master clock. The grandmaster could be:
•
A ControlLogix L7 or L8 controller when using Studio 5000 Logix
Designer software v18 or later, or
•
An Ethernet bridge that supports IEEE 1588 V2, or
•
A Symmetricom Grand Master GPS or equivalent.
What is CIP Sync?
CIP Sync is a CIP implementation of the IEEE 1588 PTP (Precision Time
Protocol). CIP Sync provides accurate real-time (Real-World Time) or
Universal Coordinated Time (UTC) synchronization of controllers and devices
connected over CIP networks. This technology supports highly distributed
applications that require time stamping, sequence of events recording,
distributed motion control, and increased control coordination.
Rockwell Automation Publication 1732E-UM003D-EN-E - November 2021
Chapter 2
Module Overview and Features
13
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