IEC 61158-3-21:2010 pdf – Industrial communication networks – Fieldbus specifications -Part 3 21:Data-link layer service definition – Type 21 elements.
DLSAP address
either an individual DLSAP address designating a single DLSAP of a single data link service (DLS) user (DLS.user), or a group DL-address potentially designating multiple DLSAPs, each of a single OLS-user
NOTE This terminology wss chosen because ISOIIEC 7498-3 does not permit h. use of he term DLSAP-address to designate more than a alngte DISAP at a single DLS-uae.
(individual) DLSAP-address
DL-address that designates only one DLSAP within the extended link
NOTE A slnØe D1-enhly may hase multiple DLSAP-addresses associated with a single OLSAP
Data link connection endpoint address (
DL-address that designates either:
a) one peer DL-connection-end-point;
b) one multi-peer publisher DL-connect’on-end-point. and implicitly the corresponding set of subscriber DL-connection-end-points where each DL-connection-end-point exists within a distinct DISAP and is associated with a corresponding distinct DLSAP-address,
Frame check sequence (FCS) error
error that occurs when the computed frame check sequence value after reception of all the octets in a data link protocol data unit (DLPDU) does not match the expected residual
synonym for DLPDLJ
network management
management functions and services that perform network initialization, configuration, and error handling
convention on the data formats, time sequences. and error correction for data exchange in communication systems
receiving DLS-user
DL-service user that acts as a recipient of DLS-user dala
NOTE A DL-eerv*ce user can be both a sending and rec&v.rig DLS-uer concurrently.
sending DLS-us.r
DL-service user that acts as a source of DLS-user data
single OLE as ii appears on one local link
b) (n) An indication that following note n contains additional information pertaining to the parameter and its use
In any particular interface, not all parameters shall be stated explicitly. Some may be implicitly associated with the DLSAP at which the primitive is issued.
In the diagrams illustrating these interfaces, dashed lines indicate cause and effect or time sequence relationships, and wavy lines indicate that events occur at approximately the same time.
3.5.2 Additional conventions
In the diagrams illustrating the DLS and DLM Interfaces, dashed lines indicate cause and effect or time sequence relationships between actions at different stations, while solid lines with arrows Indicate cause and effect time sequence relationships that occur within the DLE provider at a single station.
The following notation, a shortened form of the primitive classes defined In 3.5.1. Is used in the figures and tables.
req: request primitive
ind Indication primitive
cnf confirmation primitive (confirmation) rsp response primitive
4 Data-lInk layer services and concepts
4.1 General
4.1.1 Ov.rvlew
This standard specifies the Type 21 data link services for an ISOIIEC 8802-3:2000 based time-deterministic control network, which is one of the communication networks for RTE. The communication services support timing demands typical of high-performance automation applications. They do not change the basic principles of ISO/IEC 8802-3:2000, but extend it toward RTE. Thus, it is possible to continue to use standard Ethernet hardware, infrastructure components, or test and measurement equipment, such as network analyzers.
The Type 21 DLL provides reliable and transparent data communication between two Type 21 end devices. The Type 21 DLL also guarantees abstract transparent data transfer between DL-users so that DLL provides flexible and convenient network connectivity to networl users.
A Type 21 device is based on an integrated switch with two ports (ring ports) connected to the ring Therefore, a Type 21 network system Is made up of full-duplex, collision-free switching devices configured as a ring or a line network. Figure 1 shows the full-duplex flow control procedure in a Type 21 network system. Type 21 guarantees collision-free data transmission between two devices linked by a full-duplex Ethernet connection so that the Type 21 DLL provides reliable, transparent, and collision-free data transmission to the OLS-users.