IEEE 61588-2004 pdf download Precision clock synchronization protocol for networked measurement and control systems
This standard defines a protocol enabling precise synchronization of clocks in measurement and control systems implemented with technologies such as network communication, local computing, and distributedobjects. The protocol will be applicable to systems communicating by local area networks supporting multicast messaging including, but not limited to, Ethernet. The protocol will enable heterogeneous systems thatinclude clocks of various inherent precision, resolution, and stability to synchronize. The protocol will support systemwide synchronization accuracy in the submicrosecond range with minimal network and localclock computing resources. The default behavior of the protocol will allow simple systems to be installedand operated without requiring the administrative attention of users.
1.2 Purpose
Measurement and control applications are increasingly using distributed system technologies such as network communication,local computing, and distributed objects. Many of these applications will be enhancedby having an accurate systemwide sense of time achieved by having local clocks in each sensor, actuator, orother system device. Without a standardized protocol for synchronizing these clocks, it is unlikely that thebenefits will be realized in the multivendor system component market. Existing protocols for clock synchronization are not optimum for these applications. For example, Network Time Protocol (NTP) targets largcdistributed computing systems with millisecond synchronization requirements. The protocol proposed inthis standard specifically addresses the needs of measurement and control systems:
Spatially localized
Microsecond to submicrosecond accuracy
Administration free
Accessible for both high-end devices and low-cost, low-end devices
2. References
This standard shall be used in conjunction with the standards listed in this clause. When the following stan-dards are superseded by an approved revision, the revision shall apply.
IEEE Std 802.3″-2002, Information technology-Telecommunications and information exchange betweensystems-Local and metropolitan area networks-Specific requirements–Part 3: Carrier sense multipleaccess with collision detection (CSMA/CD) access method and physical layer specifications.
ISO 8601:2000, Data elements and interchange formats-Information interchange-Representation of datesand times.
ISO/IEC 8859-1:1998,Information technology-8-bit single-byte coded graphic character sets-Part 1:Latin alphabet No.
3. Definitions
This clause defines terms that have specific meanings in the context of the PTP.
3.1 boundary clock: A clock with more than a single PTP port, with each PTP port providing access to aseparate PTP communication path.
32 clock: A node that is capable of providing a measurement of the passage of time since a defined epoch.n this standard, the term clock is interpreted to mean either an ordinary clock or a PTP port of a boundaryclock unless otherwise stated or obvious from the context.
3.3 clock timestamp point: A point in the network protocol stack of a clock at which timestamps are generated for Sync and Delay_Reg messages sent or received by the clock. This point is defined for both theinbound and outbound paths in the protocol stack.
3.4 direct communication: A communication of PTP information between two PTP clocks with no inter-vening boundary clock.
3.5 epoch: The reference time defining the origin of a time scale.
3.6 event: An abstraction of the mechanism by which signals or conditions are generated and represented.
3.7 external synchronization: The process of bringing two clocks into a synchronized state by means otherthan the use of the PTP See also: synchronized clocks.
3.8 grandmaster clock: Within a PTP subdomain, a PTP clock that is the ultimate source of time for clocksynchronization using the PTP protocol.
3.9 interface definition language (IDL): A programming-language-independent method of specifyingoperation syntax[B11.
IEEE 61588-2004 pdf download
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