About 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. A master slave is a system of 1588 clocks that may be segmented into regions separated by boundary clocks. Within each region, there is a single clock, the master clock, which serves as the primary source of time. These master clocks will in turn synchronize to other master clocks and ultimately to the grandmaster clock. Within a given subnet of a network, there is a single master clock. All clocks ultimately derive their time from a clock known as the grandmaster clock. Within a collection of clocks, one clock, the grandmaster clock, serves as the primary source of time to which all other clocks are ultimately synchronized.This time configuration 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 timestamps.

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 GPS.

It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible.

For more information about IEEE 1588 PTP, refer to

Integrated Architecture

and CIP Sync Configuration Application Techniques

, publication IA-AT003.