Topic:
Gateway:
A number of different types of networks can be present in the car, such as CAN-A and CAN-B with different speeds, LIN bus and MOST bus. These networks cannot simply be interconnected. The light signals of the MOST bus of course cannot be seen by the CAN bus and the two CAN bus networks cannot communicate with each other due to the speed difference.
Yet it is possible for the car to be read out, where diagnostic equipment connects to the control units in all networks in the car. The gateway makes this possible. The gateway is also called the “junction” of all networks in the car. An example of this can be seen in the image below.
All networks are connected to the gateway. It effectively translates the information between the different networks. In this way, all control units can still communicate with each other and the diagnostic tester can connect to all networks. The OBD connector is therefore also connected to it. The diagnostic tester can access all networks in the car via the gateway.
If a gateway is not functioning properly, the different networks in a vehicle can no longer communicate with each other, causing multiple functions to stop working. ECUs that are normally “woken up” via the network remain switched off. A non- or poorly functioning gateway can have the following causes:
- power supply and ground are not in order;
- the clamping force of the connector on the pins in the gateway is insufficient;
- the gateway is coded incorrectly, or due to a software/hardware fault the coding has been erased;
- the hardware in the gateway is damaged as a result of a moisture problem, overload, or production issue.
The gateway must be coded after it has been replaced, or when control units have been added. The latter often happens after fitting a tow bar with an original tow bar control unit. After coding, the respective control unit is accepted in the network and with the diagnostic equipment the fault memory can be read out, live data can be viewed, actuators can be actuated, programmed, etc.
The bottom two images show a gateway (left) from an Audi and on the right the installation location (behind the glove compartment) of this gateway.
