In this article, we will discuss about the Gateway in AUTOSAR. Gateway is a feature in which a Signal, a Signal Group or a PDU received from one source bus is transmitted over another destination bus. The gatewaying of Signal, Signal group or PDU can be over two buses communicating over a same or different protocol. There are two types of gatewaying in AUTOSAR – Signal Gateway and PDU Gateway.
Signal level gatewaying happens through the COM module in AUTOSAR. COM module can gateway a Signal or a Signal Group. The received signal or signal group can be mapped to a single or multiple transmit signal or signal groups. Once a Gateway receives a signal or signal group for gatewaying, it immediately acts as a sender of that signal.
COM gateway is statically configured with gatewaying independent on the content of the Signal or Signal Group. The configuration of the gateway is done as a part of ComGwMapping container. Processing of gateway signal or signal group happens in Com_MainFunctionRouteSignals function.
PDU level gatewaying happens through the PDUR module in AUTOSAR. During gatewaying the PDUR module acts as both, the receiver and the transmitter of the PDU. PDUR receives the PDU from one lower layer module and transmits the PDU to the same or another lower layer module. A PDU can be configured to be received on one interface module and gatewayed to many interface modules. The received PDU can only be gatewayed to interface modules or TP modules but not both.
Gatewaying PDU from a source transport protocol to one or more destination transport protocol module may either be gatewayed direct as a complete PDU or as fragmented PDU where a configured number of bytes are received before transmission. Gatewaying the PDU after the complete PDU is received is called as Direct Gatewaying. Transmitting the PDU when a configured number of bytes (threshold) are received without the complete PDU being received is called as Gatewaying-on-the-fly. Only one destination module can be configured in case of Gatewaying-on-the-fly. Buffers are available in PDUR for TP gatewaying based on Direct gatewaying or Gatewaying-on-the-fly.