What about Doip? DoIP Diagnostics VS CAN Diagnostics

car diagnostic tool

Deep interpretation: DoIP diagnostic technology

DoIP diagnostics refers to the use of diagnostic services introduced via UDS over TCP/IP and Ethernet. This allows DoIP diagnostics to have faster data rates than CAN diagnostics, resulting in significant time and cost savings for complex diagnostic tasks and refresh applications.

Why use DoIP diagnostics?

High speed data transfer rate. The total data rate has reached 100 Mbit/s. Compared with the high-speed CAN using ISO-TP (ISO 15765-2), the overall rate of DoIP diagnosis is 100-200 times that of CAN diagnosis. The transmission rate on the network is 300 for CAN diagnosis. -400 times;
low cost. Use standard hardware components such as Ethernet controllers, CAT5 cables and RJ-45 connectors;

No need for hardware VCI, personal computers only need one Ethernet interface;
DoIP technology perfectly matches the IT infrastructure, and both fixed diagnostics and remote diagnostics can be applied.

DoIP Diagnostic Protocol

The DoIP diagnostic protocol is used as a transport protocol for UDS (Unified Diagnostic Service) just like ISO-TP on the CAN bus. ISO Standard 13400 specifies how Ethernet technology and Internet Protocol can be used to communicate between external test equipment and in-vehicle ECUs.


DoIP Diagnostics VS CAN Diagnostics


Connection problems in DoIP diagnostics

(1) Use virtual VCI instead of physical VCI

There is one/multiple/all DoIP entity objects on a car.
There are several/multiple DoIP entity objects on multiple cars

(2) More than just a direct physical connection (a car connected to an external test tool)

Vehicle and external tools are connected via network
Connect a car to an external test tool
Multiple cars connected to an external test tool
One car and multiple external test tools/applications

UDS package

The UDS diagnostic service is included in the DoIP message and is sent over Ethernet using the system’s TCP/IP stack.


Since the test tool is directly connected to the vehicle via Ethernet, only one special patch cable that connects the vehicle OBD interface to a normal Ethernet Cat. 5 is required for DoIP diagnostics.