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SAE J1939 Functional Safety Communications Protocol & Trailer Safety Assurance
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Commercial road and off-highway vehicles, as well as off-road construction machines, frequently utilize J1939-based application layers. In response to the growing need for functional safety, SAE has created specific protocols for CAN CC (classic) and CAN FD: J1939-76 and J1939-77, respectively.
An article on the CiA (CAN-in-Automation) website discusses the SAE standards for functionally safe communications on CAN CC (SAE document number 1-76) and CAN FD (SAE document number 1-77). SAE document number 1-76 describes the Safety Header Message (SHM) and Safety Data Message (SDM) pairing approach used to communicate safety-related data from a producing safety application to a consuming safety application. It also details the features of the original version, published in 2020, and lists the deficiencies of this version.
Finally, it describes the features of the updated version currently in development that address these shortcomings. In SAE J1939-77, the document explains how the space allocated for functional safety assurance information in the Multi-PG and FD Transport protocols is used to transmit safety-related data from a producing safety application to a consuming safety application. It also outlines three profiles currently being developed to meet various system needs while fulfilling functional safety requirements.
The IEC standard number 1 defines various communication errors that can occur. These errors include corruption, unintended repetition, incorrect sequence, loss, unaccepted delay, insertion, masquerade, and addressing. Additionally, the standard outlines safety measures that can be employed to detect these errors and achieve the desired level of functional safety. These measures include sequence numbers, time expectations, connection authentication, data integrity assurance, and redundancy with cross-checking.
The J1939-76 standard specifies two versions of functional safety support. This support applies to Parameter Groups (PGs) with parameter data payloads ranging from 1 to 8 bytes. Both versions use a Safety Data Group (SDG), which includes a Safety Header Message (SHM1 or SHM2) and a Safety Data Message (SDM), to transmit safety-related data from a producer to a consumer. The SDM, associated with an SHM, contains the safety-related parameter data used for a safety function.
The SAE J1939-77 standard provides three distinct profiles to support functional safety. Each profile is designed to meet different system requirements. These profiles use the Multi-PG and FD Transport protocols specified in J1939-22 for CAN FD. They can allocate a separate space in their messaging for cybersecurity and/or functional safety assurance information for a PG’s parameter data. This flexibility allows the standards to be customized to meet a wide range of system needs, from simple to complex, while meeting functional safety requirements. Read the article (PDF)...
SAE J1939 Starter Kit and Network Simulator
Our JCOM.J1939 Starter Kit and Network Simulator are designed to allow experienced engineers and beginners to experiment with SAE J1939 data communication without needing to connect to a real-world J1939 network, i.e., a diesel engine.
To establish a network, you need at least two nodes. This applies especially to CAN/J1939, where the CAN controller will shut down after transmitting data without receiving a response. Therefore, our jCOM.J1939 Starter Kit and Network Simulator consist of two J1939 nodes: our jCOM.J1939.USB, an SAE J1939 ECU Simulator Board with USB Port. More Information...
Industrial Grade CAN/CAN FD Bus Data Analyzer with USB Port
The USB-CAN-FD adapter is a versatile tool that empowers engineers with its industrial-grade high-performance capabilities. It serves as a USB to-CAN FD adapter, CAN/CAN-FD bus communication interface card, and CAN/CAN-FD protocol data analyzer. It is a reliable and robust solution with onboard dual independent CAN FD interfaces, electrical isolation, and multiple protection circuits. The adapter's [...]
NMEA 2000 Product Certification Guarantees Quality and Interoperability for Marine Application Networks
The NMEA 2000 product certification is a mark of reliability, ensuring quality and interoperability for NMEA 2000 networks. It guarantees that a device supports a mandatory set of protocol services and hardware requirements. Developers can carry out the certification themselves or be supported by engineers with experience in NMEA 2000 certification. NMEA 2000 is a protocol [...]
CANFDuino: Upgrading the Hardware to a 12 - 24 VDC Power Supply Input
Today, we are addressing a frequently asked question since the product's launch: 'Is it possible to power CANFDuino off of 12 or 24 V power?'. Our previous response, 'Yes, using the prototyping space to add a regulator', while accurate, may not have been as helpful as we intended. To provide a more practical solution, we [...]
Arduino-Compatible Open-Source Dual CAN-FD Network Analyzer
In a previous post, we highlighted SavvyCAN, developed by Collin Kidder, as the most effective open-source software for CAN bus sniffing. We have also worked on enhancing the compatibility of the CANFDuino and the GVRET protocol with SavvyCAN to support CANFD messages from two ports. With these updates on GitHub, you can now sniff two CANFD busses with [...]
JCOM1939 Monitor Pro - SAE J1939 Data Monitoring, Recording & Simulation
Our SAE J1939 to USB/Bluetooth gateway and the SAE J1939 Starter Kit are designed to work seamlessly with our JCOM1939 Monitor Pro Software for Windows, a free download. This combination is key to ensuring your purchased product's optimal performance and overall satisfaction. For your convenience, we have meticulously crafted a dedicated website. This one-stop hub houses [...]
SAE J1939 and OBD-II Heavy Duty Truck Scanner and Diagnostic Tool
DPF Force Regen & Reset for Cummins Caterpillar Engine -- Reset and clean your DPF professionally, quickly, and efficiently to ensure your engine runs smoothly and meets emissions standards. This all-in-one solution saves you money on maintenance costs. The Inspection Record feature records all DPF inspections to help track and manage maintenance schedules. Full System Diesel [...]
The Myth: Controller Area Network (CAN) is “Too Easy to Hack”
The potential security issues of CAN and its higher-layer protocols attract increased attention from the automotive, control, and medical industries. At first glance, believing that a well-documented standard like ISO 11898 makes it easier to manipulate control functions, whether in an automobile or a medical device such as an MRI or CT scanner, makes sense. [...]
ESP32 Processor with Internal SJA 1000 CAN Bus Controller
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USB-CAN PC Interface with SAE J1939-13 Type II Connector
The Leaf Light HS v2 J1939-13 Type II, a standout in Kvaser's Leaf Light product series, is renowned for its reliability and affordability in connecting any CAN network to a PC or mobile computer. It's not just a workhorse but a dependable and cost-effective solution. The Leaf Light HS v2 J1939-13 Type II is a device that [...]