Controller Area Network (can) Channels Explained

There can only be one speed per datalink, so if any devices (truck vs adapters) on the datalink are set at different rates the entire datalink will crash. To further explain this, 250 kbs and 500 kbs are the speeds at which messages are broadcasted on the vehicle. The solution was to make the “Green” adapter slightly different so that it works on both the green and black adapter, thus making it backward compatible. The main reason for the new “green” connector is that not all truck adapters and scanning tools are capable of reading 500 kbs, and it was feared that technicians would hook up older tools and cause damage to the tool, the truck, or both. With the new “green” connectors, this speed is doubled to 500 kbs. With all this new “traffic” on the vehicle network, the old speeds of the “black” connector trucks were limited at 250 kbs on J1939. While 10 years ago trucks may have had 2 or 3 Electronic Control Units (ECUs), today’s modern trucks are quickly approaching 20 different ECUs. Essentially, trucks have gotten more and more complicated-there are more computers, more wires, more sensors, and more technology on trucks. We have a very popular blog post that goes into the history of the first two setups and explains J1708 and J1939. The adapter connectors on trucks have been evolving since trucks first went electronic. Green 9-pin connector found on 2016 & newer commercial trucks.