1.1<\/b> General<\/p>\n
The data-link layer provides basic time-critical messaging communications between devices in an automation environment.<\/p>\n
This protocol provides communication opportunities to all participating data-link entities<\/p>\n
in a synchronously-starting cyclic manner, according to a pre-established schedule, and<\/p>\n<\/li>\n
in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those data-link entities.<\/p>\n<\/li>\n<\/ol>\n
Thus this protocol can be characterized as one which provides cyclic and acyclic access asynchronously but with a synchronous restart of each cycle.<\/p>\n
1.2<\/b> Specifications<\/p>\n
This standard specifies<\/p>\n
procedures for the timely transfer of data and control information from one data-link user entity to a peer user entity, and among the data-link entities forming the distributed data-link service provider;<\/p>\n<\/li>\n
procedures for giving communications opportunities to all participating DL-entities, sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic intervals;<\/p>\n<\/li>\n
procedures for giving communication opportunities available for time-critical data transmission together with non-time-critical data transmission without prejudice to the time-critical data transmission;<\/p>\n<\/li>\n
procedures for giving cyclic and acyclic communication opportunities for time-critical data transmission with prioritized access;<\/p>\n<\/li>\n
procedures for giving communication opportunities based on standard ISO\/ IEC 8802-3 medium access control, with provisions for nodes to be added or removed during normal operation;<\/p>\n<\/li>\n
the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units.<\/p>\n<\/li>\n<\/ol>\n
1.3<\/b> Procedures<\/p>\n
The procedures are defined in terms of<\/p>\n
the interactions between peer DL-entities (DLEs) through the exchange of fieldbus DLPDUs;<\/p>\n<\/li>\n
the interactions between a DL-service (DLS) provider and a DLS-user in the same system through the exchange of DLS primitives;<\/p>\n<\/li>\n
the interactions between a DLS-provider and a Ph-service provider in the same system through the exchange of Ph-service primitives.<\/p>\n<\/li>\n<\/ol>\n
1.4<\/b> Applicability<\/p>\n
These procedures are applicable to instances of communication between systems which support time-critical communications services within the data-link layer of the OSI or fieldbus reference models, and which require the ability to interconnect in an open systems interconnection environment.<\/p>\n
Profiles provide a simple multi-attribute means of summarizing an implementation\u2019s capabilities, and thus its applicability to various time-critical communications needs.<\/p>\n
1.5<\/b> Conformance<\/p>\n
This standard also specifies conformance requirements for systems implementing these procedures. This standard does not contain tests to demonstrate compliance with such requirements.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 6<\/td>\n | CONTENTS <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 1 Scope 1.1 General 1.2 Specifications 1.3 Procedures <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | 1.4 Applicability 1.5 Conformance 2 Normative references 3 Terms, definitions, symbols and abbreviations <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 3.1 Reference model terms and definitions <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 3.2 Service convention terms and definitions 3.3 ISO\/IEC 8802-3 terms <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 3.4 Common terms and definitions <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | Figures Figure 1\u00a0\u2013\u00a0Relationships of DLSAPs, DLSAP-addresses and group DL addresses <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 3.5 Symbols and abbreviations <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 4 Overview of the DL-protocol 4.1 General Figure 2\u00a0\u2013\u00a0Communication model <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 4.2 Services provided by the DL <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | 4.3 Structure of deterministic communication scheduling Figure 3\u00a0\u2013\u00a0Type\u00a014 packet identifier Figure 4\u00a0\u2013\u00a0Time-sharing communication scheduling <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 5 Procedure of deterministic communication scheduling 5.1 Overview <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | 5.2 State transitions Figure 5\u00a0\u2013\u00a0State transitions of ECSME <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 5.3 State table Tables Table 1\u00a0\u2013\u00a0ECSME state transitions <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 5.4 Function descriptions Table 2\u00a0\u2013\u00a0NonperiodicDataSendingSuc() description Table 3\u00a0\u2013\u00a0NonperiodicDataAnnunciation() description Table 4\u00a0\u2013\u00a0NonperiodicDataSending() description <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Table 5\u00a0\u2013\u00a0NonperiodicDataSendingSuc() description Table 6\u00a0\u2013\u00a0FirstNonperiodicDataSending() description Table 7\u00a0\u2013\u00a0NonperiodicDataPriority() description <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Table 8 \u2013 NonperiodicDataTimeEnough() description Table 9\u00a0\u2013\u00a0NonperiodicDataSending() description Table 10\u00a0\u2013\u00a0EndOfNonperiodicDataSending() description <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Table 11 \u2013 IsDeviceConfigured() description Table 12\u00a0\u2013\u00a0CountOffsetTime() description Table 13\u00a0\u2013\u00a0DataSendingTiming() description Table 14\u00a0\u2013\u00a0RecEndofNonPeriodicDataSending() description <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | 6 Structure and encoding of ECSME PDU 6.1 ECSME PDU structure Figure 6\u00a0\u2013\u00a0Format of NonPeriodicDataAnnunciation PDU <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure 7\u00a0\u2013\u00a0Format of EndofNonPeriodicDataSending PDU Figure 8\u00a0\u2013\u00a0Format of Type\u00a014 PDU Figure 9\u00a0\u2013\u00a0Format of Type\u00a014 PDU for FRT application <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | 6.2 Encoding of ECSME packet Table 15\u00a0\u2013\u00a0NonPeriodicDataAnnunciation message encoding <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Table 16\u00a0\u2013\u00a0EndofNonPeriodicDataSending message encoding Table 17\u00a0\u2013\u00a0Type\u00a014 DL-management Tag encoding <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Table 18\u00a0\u2013\u00a0Type\u00a014 message encoding Table 19\u00a0\u2013\u00a0Type\u00a014 message for FRT application encoding <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Industrial communication networks. Fieldbus specifications – Data-link layer protocol specification. Type 14 elements<\/b><\/p>\n |