Diagnostic Connector: Gateways
On some of the early models the D-Bus was connected directly to some modules. Some modules were diagnosed through a gateway module such as the IKE or cluster. For instance as the diagram below shows, modules that are on the I, K and P-Bus must be diagnosed through the IKE. In this case the IKE acts as a "gateway" module. The gateway routes all diagnostic "traffic" to the correct bus system.
On newer vehicles such as the E65, the ZGM acts as a gateway and all diagnostic data is routed through this module.
A gateway allows information to be transferred from one bus system to another. Due to the difference in communication speed, the gateway must "translate" the data and then route the data to the correct network.
In addition to the above functions, the gateway will also allow data messages with a higher priority to be transmitted first.