USB CAN Adapter : Working, Applications, Manufacturers

Introduction : A USB CAN Adapter bridges your PC or laptop to a Controller Area Network (CAN) bus. It enables seamless communication with CAN enabled devices directly over a USB port. These adapters offer support for standard CAN protocols (e.g. CAN 2.0A/B) and high speed data transfer up to 1 Mbps. These adapters make it easy to monitor, test or log CAN bus traffic without needing specialized hardware.

How USB to CAN Adapter Works

As the name suggests, it connects one side with USB port and the other side with CAN bus via. DB9 connector to CAN_H and CAN_L lines. Let us understand working of USB-CAN converter.

1. USB to CAN : On the transmit side, computer creates message which is received by adapter via USB connector. The message is processed by microcontroller and CAN controller and formats it into CAN frame. The logical signals of this CAN frame is converted further by CAN transceiver into appropriate differential voltages as per logical-0 and logical-1. The converted differential voltages are broadcasted onto the CAN bus. The basic can frame consists of various fields such as Start oF Frame, Identifier, CRC etc.

2. CAN to USB : On the receive side, adapter listens to the bus. When it detects the CAN frame, transceiver converts the differential voltages back to digital logic. The controller first varifies CRC and de-stuffs the bits. The valid message is packaged into USB packet format and sent to computer software for display or logging or analysis.

In addition to above two major functions, adapter also participates in bus arbitration.

Applications

Following are some of the applications or use cases of usb to can and can to usb converters.

• Network Monitoring/Sniffing: Reading traffic between ECUs to debug communication errors.
• Data Logging: Recording long term data for analysis of intermittent faults.
• ECU Simulation : The adapter can simulate missing ECU by sending the messages that ECU would normally send, allowing developers to test other components in isolation.
• Diagnostics (OBD): Sending specific request frames to retrieve diagnostic trouble codes (DTCs).
• Flash Programming: Uploading new firmware to ECU via the bootloader over CAN.

Manufacturers

Following are some of the companies which manufacture USB CAN adapter device.

Summary: The USB CAN adapter helps in debugging ECUs, logging CAN messages or building custom CAN based applications. This adapter offers a cost effective, robust gateway between your general purpose PC and embedded CAN networks.