Can bus comunication non intrusive


i wanna know if someone worked already with this kind of technology and have a component that i could check to start making a prototipe.

the circuit sense the canbus line througth the magnetic field that the wire produce, i think it amplifies the signal to read it on the micro but im not sure its the right pad

I've never seen something like that. Do you lay the CANHI and CANLO wires along the circuit board and it detects the signals? That looks more like a capacitive coupling. In dominant state your would get a differential voltage on the two capacitors In recessive state they would be at about the same voltage. I would guess it's a FET input amplifier and maybe a comparator to make the signal digital.

The best way to monitor CAN is to electrically connect a CAN transceiver to the CAN lines. On vehicles there is almost always a connector that can be used to connect to the CAN bus. I am less familiar with CAN in industrial settings, but I would guess that a connector or terminal strip would be very common.

You could do it with an inductive sensor, but you'll have to separate the wires and only sense one. If you put an inductive coil or sensor around both wires you won't get any signal.

CAN has about 3V differential in the dominant state, so with a 120 Ohm termination resistor you will see around 25mA of current. That should be detectable with a suitable inductive pickup. The current will be in different directions depending on which side of the sensor the transmitting node is located, so you will want to make your detection circuit respond to either polarity. In the recessive state the current will be very nearly zero so it should be pretty easy to differentiate.

All the ones I find have power, ground, CAN-H, and CAN-L wires. I have not found any projects that connect CAN-H and CAN-L directly to the Arduino. It may be possible but it looks like you will have to develop the techniques on your own.

Would you be willing to use a CAN Bus Shield? That will add a CAN Bus Transceiver and CAN Bus Controller to your Arduino.

Thanks fot the reply,

I have a working program to read the canh and canl but i would like to have a better aproach than peeling the wires and conecting the cable to it. I saw this product that you pute the wires on the designed pad and it has a plastic cover to holdthem in place, the signal goes througth the cable to the can tranciever.

I want to make that part where you put the canh cable on a copperpad (another copperpad to canl) and detect the pulses without cutting the wire.

So this is not in a car that has an ODB-II connector under the dashboard?

As I said, CAN is a balanced network in both voltage and current, so anything that surrounds the both wires of the twisted pair will see exactly the same average voltage (2.5V) and current (0) in both the dominant and recessive states. I don't think there is any simple way to monitor CAN without connecting electrically or separating the twisted wires for a section.