Softing Supports a Standardized Diagnostic Protocol

July 22, 2021

Peter Subke

On-board diagnostics (OBD) is required to monitor emissions-related components such as heavy-duty diesel engines and their emissions control systems. Though the use of electric drives is increasing, not only in passenger cars but also in heavy-duty commercial vehicles and mobile machinery, the legally required OBD system will not disappear. Independent of the current legal situation, the OBD system is being expanded and given new tasks. Especially in autonomous road-vehicles and automated mobile machines, this enhanced on-board diagnostics is indispensable to ensure availability and safety.

Diversity is not always an advantage, especially when it creates unnecessary effort and costs. The current situation is that the industry faces three different OBD protocols: Heavy-Duty (HD)-OBD (SAE J1939-73), SAE-OBD (SAE J1979), and World-Wide Harmonized (WWH)-OBD (ISO 27145). All three are based on the same set of “OBD modes” and exclusively support emissions-related functions. For enhanced diagnostics, the internationally standardized UDS (unified diagnostic services) on CAN (ISO 14229-3 and ISO 15765-4) can be considered as state of the art. As a result, manufacturers of vehicles and machines that are powered by heavy-duty diesel engines implement both OBD on CAN and UDS on CAN.

To solve this diversity problem, the WWH-OBD as it is specified in the Global Technical Regulation GTR No. 5 of the United Nations has been developed to replace both SAE-OBD and HD-OBD protocols. WWH-OBD is based on UDS, meaning that only one diagnostic protocol is necessary for emissions- and safety-related OBD and enhanced diagnostics: UDS on CAN. “Replacing proprietary diagnostic test equipment by an internationally standardized, data-driven and cloud-based technology makes both technical and economic sense,” said Julian Erber, product manager at Softing Automotive.

Diagnostic test equipment

The generic term “diagnostic test equipment” is referred to as the Tester (TST). Figure 2 shows a common setup of a TST, a vehicle communication interface (VCI) and a device under test (DUT). Effective diagnostic procedures that meet the “right-first-time” approach require smart-diagnostic test equipment to support the service technician.

All components of such a smart diagnostic system are internationally standardized by ISO (Table 1). Using an MVCI-Server (ISO 22900) that processes Open Diagnostic eXchange format (ODX - ISO 22901) data can be considered as state of the art. The generic D-PDU API for the connection between the TST and the VCI has been proven to have a better performance than the industry standards RP1210 and SAE J2534. Open Test sequence eXchange format (OTX - ISO 13209) for the description of diagnostic and test sequences is on the rise.

The technology of the MVCI-Server and the OTX-Runtime ensures platform independency (WIN, Android, iOS, LINUX). The same is true for Qt-/QML-based graphical user interfaces (GUIs). For a successful inspection and maintenance (I/M) procedure, both the TST and the DUT must support the same diagnostic protocol. If the DUT is a combustion engine, its engine control module (ECM) must support both OBD on CAN and UDS on CAN.

Smart diagnostic tool

Figure 3 shows “Softing TDX” (Tester for DiagnostiX), which is a technology to create and maintain a cloud-based smart diagnostic tool. The entire tool chain is based on international standards. Using TDX Templates, the content development tools are used to create TDX content, such as ODX data, OTX scripts, GUI elements and cloud-based web services.

TDX supports OBD and UDS on CAN and can be extended to support UDS on IP (Ethernet) by simply adding another template. The protocol templates are delivered as ODX files. Examples of OTX scripts include flash jobs, guided fault-finding sequences or procedures that support preventive and predictive maintenance.

TDX is a technology that supports vehicle manufacturers and their suppliers in the development of their own diagnostic system. Typical users are manufacturers of electrohydraulic control systems, electric and hybrid-electric vehicle (EV and HEV) components, engines and emissions control systems, ag tractors, special-purpose vehicles such as firetrucks, commercial trucks and buses, as well as motorcycles, trikes and quads.

Templates cover the most common use cases such as vehicle/ECU-identification, fault code management, handling of measured values and flash jobs. OTX scripts, business logic and a GUI proposal are prepared and ready to be used for all templates.

Bosch Rexroth, a leader in electrohydraulic systems especially for mobile machines, has developed the Bosch Rexroth Digital Application Solution (BODAS-service 4.x). A TDX-based flash and service tool for electronic devices, BODAS supports RC 40 controllers, directional valves, off-highway inverters and ultrasonic / radar sensors from Bosch. Figure 4 shows a screenshot of BODAS-service 4.x.

The application is internally used by Bosch Rexroth and externally by customers for the configuration of BODAS-ECUs, machine commissioning and diagnostic testing. Updates are performed via the Bosch Rexroth Internet infrastructure. “We were looking for a scalable, open diagnostic software for our new BODAS controllers that would also offer easy access – in other words, something that would suit us 100%. And with Softing TDX, we found the right tool for that,” said Robert Stawiarski, product manager tools at Bosch Rexroth AG.

Dipl.-Ing Peter Subke of Softing Automotive Electronics wrote this article for SAE Mobility Media.

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