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I have read a lot of postings and solutions here in stackoverflow. I am very new to CAN networks and protocols and currently working on a project that entails communicating with the Vehicle engine Control Unit to cause the vehicle to decelerate to a preset speed. Basically, I intend to establish a node in the CAN network where I can inject packets of data to the engine ECU to cause the car to decelerate to a predefined speed. How do I translate signals received on the CAN bus, meant for the ECU, so as to make it possible for ECU to decode? I plan to send two speed signals to the ECU. speedSignal_1 = current vehicle speed speedSignal_2 = target vehicle speed. My intention is to make the ECU force the vehicle at current vehicle speed (speedSignal_1) to reduce to the target vehicle speed (speedSignal_2). Can you advice me on how to proceed in achieving this?

Thanks

the_Stick
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  • Have you done _any_ research into communicating on a CAN bus at all yet? As it stands, this question is _far_ too broad for Stack Overflow. – James Thorpe May 01 '15 at 11:11

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DISCLAIMER: Experimenting with the CAN bus on a moving vehicle is extremely dangerous. If you must audit an active vehicle, make sure that it is secured in a way in which it cannot escape and you cannot lose control (raised with wheels off the ground, on rollers, etc). Use the information in this post at your own risk. In no event shall I be liable for any direct, indirect, punitive, incidental, special consequential damages, to property or life, whatsoever arising out of or connected with the use or misuse of this information.

Your question assumes that the model of car that you're working on has this functionality built in. If your car has cruise control, you can most likely try and figure out what CAN messages are sent out when you activate the cruise control and modify the message to request the speed that you desire. The information regarding the exact message parameters is often proprietary to the manufacturer though, so you will most likely have to do some reverse engineering to figure out the correct messages by listening to the correct CAN bus and toggling the cruise control on/off.

aliaoca
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