Is CAN bus the same as OBD2?
Link between OBD2 and CAN bus On board diagnostics, OBD2, is a ‘higher layer protocol’ (think of it as a language) while CAN bus is a method for communication (like a telephone). In particular, the OBD2 standard specifies the OBD2 connector, incl. a set of five protocols that it can run on.
CAN bus high CAN low?
CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines.
Where is the OBD-II port located?
The OBD-II port is usually located under the dashboard, beneath the steering wheel column (1 – 3 in the diagram below).
Why do we use CAN protocol for OBD?
The main reason is that most of the new vehicles use Controller Area Network (CAN) protocol for OBD communication. When a data request is send by the diagnostic tool, the electronic control units (ECUs) will respond to this message by transmitting the requested data value last determined by the system.
What does request current mean in OBD diagnostic mode?
The request is a stream of maximum 7 bytes. The first byte represents the service/mode identifier, which for Read Current Diagnostic Data is 01. From second byte up to the seventh are the IDs of the parameters we want to read (PIDs). In one request up to 6 PIDs can be requested. The minimum number of requested PIDs is 1, the maximum is 6.
Can bus and OBD II explained For Dummies?
CAN Bus and OBD II Explained For Dummies, with Examples of how CAN Bus and OBD II Work! CAN Bus and OBD II Explained For Dummies, with Examples of how CAN Bus and OBD II Work!
Can you request an OBD II PID from ECU?
You cannot request whatever you want from ECU (at least in a normal way!). Only the OBD relevant PIDs you can request. All the OBD II PIDs and their definitions, scaling and etc. are available within ISO 15031 part 5. It means that all the PIDs are predefined.