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Industrial networking is vital to today’s manufacturing landscape. From different types of networks to key components and best practices, this guide will help you navigate the intricacies of industrial Ethernet networking. See video.
As shown in the below picture, the CAN bus level typically ranges (Common-Mode-Voltage = 0V) between 1.5 (CAN_L during dominant bit) and 3.5 Volts (CAN_H during dominant bit). However, the actual signal status, recessive or dominant, is based on the differential voltage Vdiff between CAN_H and CAN_L.
SAE J1939 Quick Reference
- Higher-Layer Protocol using CAN as the physical layer
- Shielded twisted pair wire
- Max. network length of 40 meters (~120 ft.)
- Standard baud rate of 250 kBit/sec
- Max. 30 nodes (ECUs) in a network
- Max. 253 controller applications (CA) where one ECU can manage several CAs
- Peer-to-peer and broadcast communication
- Support for message length up to 1785 bytes
- Definition of Parameter Groups (Predefined vehicle parameters)
- Network Management[1] (includes address claiming procedure.
It must be emphasized that the maximum network length of 40 m (roughly 120 ft.), the baud rate of 250 kBit/sec and the maximum number of nodes (30) are self-inflicted restrictions by the SAE, most probably with the intention to keep everything on the extreme safe side and thus trying to prevent potential runtime problems.
In all consequence, the network length at 250 kBit/sec, according to ISO 11898, is 250 m (roughly 750 ft).
In this guide we introduce the J1939 protocol basics incl. PGNs and SPNs.
Note: This is a practical intro so you will also learn how to decode J1939 data via DBC files, how J1939 logging works, key use cases and practical tips.
Learn below why this has become the #1 introduction to J1939.
You can also watch our J1939 intro above - or get the PDF