So basically I bought SparkFuns CANBus Shield and a DB9-OBD cable. I’ve connected my car via OBD port to Arduino, flashed the “CAN_Read_demo.ino” sketch, but no messages were received after turning on the car (I’ve also tried different speeds).
I understand that the shield has no termination, so my question is - how exactly can I connect my CANBus Shield to my car and perform a sniffing process and how and where should I connect resistors?
Thank you in advance.
For a car, you shouldn’t need any resistors, they will already be present on the CAN bus.
How old is your car? Older models don’t always output CAN or might output it on different pins.
You can try a 120 ohm resistor between the CAN_H and CAN_L pins on the board but it isn’t needed for modern cars.
I’ve tried it with VW Golf Mk5 and with VW Scirocco.
About the resistor - how do I connect the resistor when the cable is connected to DB9 port on the shield?
Should I maybe connect DB9 pins directly into CANH and CANL pins on the shield and not via DB9 port?
There are CAN_H and CAN_L pins right on the board you can connect the resistor too.