A JCOM1939 Engineering Note on Error Handling, Bus Off, and Silent Mode in Two-Node CAN Networks JCOM1939.com | Copperhill Technologies | © 2026 Controller Area Network (CAN) is well known for its robustness. Arbitration prevents message collisions from corrupting data, error detection identifies damaged frames, automatic retransmission provides another opportunity…
Posts published in “Reports”
Comprehensive insights, analysis, and technical reports on SAE J1939 data communication, monitoring tools, industry trends, and vehicle network technologies.
Developing, testing, or diagnosing SAE J1939 networks requires more than simply connecting a CAN interface to a PC. Engineers often need to monitor network traffic, decode messages, simulate electronic control units (ECUs), request diagnostic data, and verify that embedded software behaves correctly under real-world conditions. The market offers a wide…
When the first versions of SAE J1939 emerged in the late 1980s and early 1990s, the objective was straightforward: provide a standardized communication protocol for electronic control units (ECUs) in heavy-duty trucks. At the time, vehicle manufacturers were rapidly increasing the number of electronic subsystems, creating a need for a…
SAE J1939 is a standardized, CAN-based in-vehicle communications suite widely used in heavy-duty and off-highway domains, enabling interoperable exchange of operational telemetry (e.g., speed, engine hours, fuel rate) and a structured diagnostic ecosystem (Diagnostic Messages “DMs” and Diagnostic Trouble Codes “DTCs”). Its core fleet-management value is not “a single feature,”…
CAN-XL (Controller Area Network eXtra Long) and Automotive Ethernet represent two different approaches to in-vehicle networking. CAN-XL is the upcoming third-generation CAN bus protocol, evolving the classical CAN/CAN-FD architecture to support higher data rates (on the order of tens of Mbit/s) and larger message payloads while retaining CAN’s low-cost, real-time…
John Deere agricultural vehicles, such as this modern tractor, utilize J1939 CAN networks for critical systems. These in-vehicle networks carry engine, transmission, hydraulic, and safety data, and are designed to be robust and reliable. John Deere’s implementation of J1939 is closed and tightly controlled, reflecting the company’s emphasis on safety,…
SAE J1939 is a communication protocol that standardizes how heavy-duty vehicle components (engines, transmissions, brakes, etc.) exchange data over the CAN bus. Modern trucks, buses, and off-road machines generate a wealth of operational and diagnostic data on these J1939 networks. Traditionally, this data was accessed locally (e.g. via mechanic’s scan…
Introduction SAE J1708/1587 in Today’s Fleet Maintenance: SAE J1708 (often used with the J1587 data protocol) was the dominant heavy-duty vehicle network standard from the early 1990s through the mid-2000s. It formed the backbone for diagnostics on older trucks via the 6-pin diagnostic connector. While modern commercial vehicles have largely…
In the late 1980s and 1990s, heavy-duty vehicles (like diesel trucks and buses) began using electronic networks to share data among engine, transmission, brake, and other control units (ECUs). The industry’s first standardized solution was a combination of SAE J1708 and SAE J1587. In this two-part system, J1708 defined the…
Older diesel vehicles using the SAE J1708 bus (with J1587 protocol) can be retrofitted with modern SAE J1939-based dashboards and instruments by using specialized protocol gateway converters. These devices bridge the hardware (RS-485 vs. CAN) and data-format gap between legacy J1708/J1587 engine networks and new J1939/CAN networks. Below, we survey…
