Truck & Off-Highway Engineering - August 2023 - 6

TECHNICAL INNOVATIONS
TESTING
Software-defined
vehicles drive
revamped design
strategies
Figure 5: Assignment of UDS requests to SAE J1979 OBD II test modes.
Automated driving, electrification,
cloud computing and the push toward
software-defined vehicles are forcing
automotive and commercial-vehicle
developers to revamp design strategies.
Tools suppliers are moving to help engineers
develop and verify solutions that
address the complete vehicle environment,
a task that requires a growing
number of design tools.
During the recent dSPACE World
Figure 6: SAE Recommended Practices referenced by SAE J1979-2 and -3.
Figure 4 shows the 26 Unified
Diagnostic Services (UDS) as they are
specified in ISO 14229-1. The services can
be parameterized by sub-function bytes
and/or Data Identifiers (DIDs). Figure 5
shows that the nine SAE J1979 OBD II
Modes can be replaced by four ISO 142291
services. For example: OBD II Mode with
the SID 0x09 = " Request vehicle information "
and the PID 0x02 will be replaced by
the UDS Request 0x22 = " Read data by
identifier " and the 2-byte Data Identifier
0xF802. Both positive responses will contain
the Vehicle Identification Number
(VIN) of the vehicle.
Because ZEVonUDS covers vehicles
with no emissions, the emission-related
failures are replaced by ZEV propulsionrelated
failures. The OSI Layer 6 of both
SAE J1979-2 and -3 reference several other
SAE Recommended Practices and their
Digital Annexes (DA) (see Figure 6).
J1979-2 and -3 differentiate two DTC
(diagnostic trouble code) formats:
SAE_J2012_DTCFormat_04 and SAE_
J1939-73_DTCFormat. An ECU shall
only support one DTC format. SAE
6 August 2023
J1979-2 and -3 are applicable for passenger
cars with SAE J2012 DTCs as
well as for heavy-duty trucks with SAE
J1939 DTCs. If a vehicle or engine uses
DTCs in the SAE J1939 format, they can
be encoded using SAE J1939 SPNs
(Suspect Parameter Numbers) as they
are listed in SAE J1939 DA with FMIs
(Failure Mode Identifiers) defined in
SAE J1939-73 Appendix A.
The SAE J1979 OBD II Modes will be
replaced by new UDS-based service
requests. Even if the lower OSI model
layers for both old and new protocol
stacks remain the same, vehicle manufacturers
and their E/E system suppliers
as well as tool suppliers must upgrade
their technology. A mixture of J1979
and UDS-based protocols is no longer
allowed. This is a major step in the direction
of finally having only one worldwide
harmonized diagnostic protocol:
UDS on IP.
Peter Subke, director business
development at Softing Automotive
Electronics GmbH, wrote this article for
Truck & Off-Highway Engineering.
dSPACE CEO Carsten Hoff detailed plans to see if
some companies can work together to help users
share data created using disparate design tools.
TRUCK & OFF-HIGHWAY ENGINEERING
Conference in Munich, Germany, several
vehicle manufacturers described their
strategies for coping with these trends.
dSPACE, which supplies hardware/software-in-the-loop
(HIL/SIL) tools, announced
plans to see if tool makers can
find a way to help developers by making
it easier to integrate data created
using different development software.
" Several companies are doing verification
and validation tools, so it's a
challenge to integrate everything into a
seamless tool chain, " said Carsten Hoff,
CEO at dSPACE. " We want to invite
companies to discuss creating an industry
platform. We want to see if we as an
industry can find the right consortium,
with different companies contributing
to make life easier for users. "
FROM TOP: SOFTING; SOFTING; dSPACE
Truck & Off-Highway Engineering - August 2023

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