Rockwell Automation Ethernet Design Considerations Reference Manual - Manual (Page 75)

Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 75
EtherNet/IP Protocol Chapter 4
Typical time synchronized applications include the following:
• Input time stamping
–
Events and alarms
– Sequence of Events recording
– First fault detection
• Time scheduled outputs
• Integrated motion on EtherNet/IP drive synchronization
• Distributed motion control
CIP Sync a time synchronization extension to the application layer can help solve
these application requirements. CIP Sync is based on the IEEE 1588 (IEC
61588) standard—Precision Clock Synchronization Protocol for Networked
Measurement and Control Systems, commonly referred to as the Precision Time
Protocol (PTP). The protocol provides a standard mechanism to distribute
Coordinated Universal Time (UTC) across a standard Ethernet network of
distributed devices. By time stamping in UTC events can easily be compared
across time zones without having to be adjusted for the geography in which they
were generated.
CIP Sync lets users base control on true time synchronization rather than the
more limited event synchronization model used historically. In a 100 Mbps
switched Ethernet system, advanced testing shows CIP Sync can deliver time
synchronization accuracy of less than 500 ns between devices, meeting the
requirements of some of the most demanding real-time applications.