wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

45-12 Industrial Communication Systems
The identification of the slaves is provided by the LIN Product Identification, where a 32 bit value
identifies the supplier ID, the function ID, and the variant. The data field of the “assign NAD” request
(it is a MRF) carries the following information: first byte is the initial NAD (old NAD); high nibble of
second byte is the ID of SF (0x0); low nibble of second byte is the data length plus one (for the SID or
RSID); third byte, the SID (0xB0—assign NAD); byte four and five is the supplier ID; byte six and seven
is the function ID and byte eight is the new NAD. If the NAD, the supplier ID, and the function ID
match, the slave answers to the header of the SRF with a positive “assign NAD” response. The third byte
carries the response service identifier (RSID). The SID + 0x040 represents a positive acknowledgment
(here, 0xF0 for positive assign NAD response).
45.8 Configuration
As stated earlier, a LIN cluster can be configured using automated tools that use the CLD to describe the
cluster, in an LDF. A first step is to create a cluster message strategy to completely describe the required
communication between all units in the cluster. A list of all frames is generated that includes frame IDs,
publishers and subscribers, data content, etc. A schedule table can also be described for the cluster.
All of these parameters are described by the LDF.
LIN2.x also defines the “off-the-shelf” approach for a dynamic configuration, which affords a simple
plug-and-play feature for the slave nodes. This approach is based on the node configuration and identification
services. The main services for the node configuration are the above-mentioned “assign NAD”
as well as the “assign frame ID” (LIN2.0) and “assign frame ID range” (LIN2.1) services. With the latter
service, one can assign and change the protected identifier of a frame.
If more identical slave nodes are used in a cluster (e.g., damper motors in an air-conditioning system),
the address conflict can be resolved via a slave node position detection (SNPD) procedure only. One
possible algorithm is the Bus Shut Method (also called “cool-LIN”) that is described in the patent WO
03/094001 A1 [WO03]. Another algorithm is the Extra Wire Daisy Chain method. (In this area, there
are more patents, e.g. [US59].)
45.9 relationship between SAE J2602 and LIN2.0
In March of 2004, the SAE approved the SAE J2602 recommended practice for the use of LIN, based
upon the released LIN2.0 specification.
The SAE J2602 recommended practice narrows down some of the choices allowed in the LIN2.0 specification
to ensure a greater degree of interoperability and to provide a minimum level of performance
characteristics among SAE J2602 compliant nodes.
The most significant differences in implementing an SAE J2602 compliant LIN network and a LIN2.0
compliant network are in the diagnostics and network configuration support as well as the restriction
on a single bus speed of 10.417.kbps that allows tightening of the physical layer specifications. It was
decided that the LIN2.0 diagnostics requirements should be optional for SAE J2602 implementations.
Usage of the network configuration methods were also simplified and further specified, particularly the
inclusion of a device node number (DNN) as a part of the slave node address (NAD).
45.10 Conclusion
This chapter has introduced the LIN bus concepts and has provided an insight into the LIN specifications,
highlighting some of the more important technical details. LIN has now been established as the
de facto network technology for the implementation of simple and cost-effective equipment clusters in
the vehicle. Today, numerous vehicles employ LIN in the body/convenience areas of the vehicle. LIN
will succeed into the future as it has many advantages in that it is simple to engineer, with many supporting
design tools. Hardware components are readily available, the implementations are very cost
© 2011 by Taylor and Francis Group, LLC