In this article, we will discuss the Diagnostic Communication Manager (DCM) module in AUTOSAR.
The DCM module ensures and manages the flow of diagnostic data along with diagnostic sessions and security states. The DCM module services the request only after checking whether the requested service is supported under the active the diagnostic session and under the active security level.
The DCM module supports most of the services listed under UDS ISO-14229-1 and OBD ISO-15031-5 standards.
The network specific functionalities are handled outside the DCM module making it a network independent module. The DCM module receives a diagnostic request from the PDUR module. It checks for the support of the service under the active session and states. If the service is supported then it interacts with other BSW modules or SWC’s to collect the service response. It assembles the response and sends it back through the PDUR module.
The DCM module can be subdivided into three sub modules like Diagnostic Session Layer (DSL), Diagnostic Service Dispatcher (DSD) and Diagnostic Service Processing (DSP).
Diagnostic Session Layer (DSL): It manages the diagnostic sessions, security level and the protocol / application layer timing. It also ensures the data flow concerning the diagnostic request and response. This sub-module interacts with the PDUR module to manage the data flow. DSL informs the DSD about the incoming request and provides the data.
Diagnostic Service Dispatcher (DSD): It checks the validity of the incoming service request and also tracks the progress of the service request. If the diagnostic request is valid, it processes the stream of diagnostic data. It receives the diagnostic request and forwards for data processing. It transmits the response after data processing.
Diagnostic Service Processing (DSP): Manages the diagnostic service request. Analyzes the requested service for the format (message length and structure) and subfunction support. Interacts with other BSW modules and SWC’s to acquire the data required for the service response. It also assembles the service response.
We will continue our discussion on DCM and other AUTOSAR diagnostic modules in the coming articles.