The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities,
sequentially and in a cyclic synchronous manner. Foreground scheduled access is available
for time-critical activities together with background unscheduled access for less critical
activities.
Deterministic and synchronized transfers can be provided at cyclic intervals up to 1 ms and
device separations of 25 km. This performance is adjustable dynamically and on-line by reconfiguring
the parameters of the local link whilst normal operation continues. By similar
means, DL connections and new devices may be added or removed during normal operation.
This protocol provides means to maintain clock synchronization across an extended link with
a precision better than 10 μs.
This protocol optimizes each access opportunity by concatenating multiple DLSDUs and
associated DLPCI into a single DLPDU, thereby improving data transfer efficiency for datalink
entities that actively source multiple streams of data.
The maximum system size is an unlimited number of links of 99 nodes, each with 255 DLSAPaddresses.
Each link has a maximum of 224 related peer and publisher DLCEPs.
IEC 61158-4-2:2010 history
2023IEC 61158-4-2:2023 Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements
2019IEC 61158-4-2:2019 Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements
2014IEC 61158-4-2:2014 Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification -Type 2 elements
2010IEC 61158-4-2:2010 Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification -Type 2 elements
2007IEC 61158-4-2:2007 Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements (Edition 1.0)