The CAN Network Management interface module is a part of the service layer of the BSW module in classic AUTOSAR architecture. The CanNM Tutorial describes the concept, configuration, dependent modules, and functionalities of the CAN Network Management module.
Introduction To AUTOSAR CAN Network Management (CanNM)
The CAN Network Management (CanNM) module is a part of the CAN module in the BSW communication service layer. This module is used to handle all the possible modes on the CAN Network. Since the CAN protocol is a network-based protocol, it is difficult to handle all the nodes or ECU in a single network. It is important to control because the vehicle is having different modes. If you will not handle all these, all the nodes will be staying in active mode. Even if they will not be able to identify with each other in a network. And also your battery will down very soon for which you need to change it.
Even if sometimes due to parking mode or accessory mode there is a heavy possibility of the battery down. When after that you came back to drive your battery might not have sufficient power to start your vehicle. So it is very important to manage the CAN network and ON or OFF the ECUs as per the requirement.
Functions Of AUTOSAR CAN Network Management (CanNM)
There are multiple functions that are handled by the CanNM module. The main purpose of CanNM is to co-ordinate the transition between the CAN network Normal operation and sleep operation mode. In addition to the main core functionality, it provides the service to detect all the nodes present in a particular network. Even if it also can detect that either all the nodes are ready to go to sleep mode or not. These kinds of functionality can be configurable by the AUTOSAR tools available like Vector Davinci Configuration Tool.
AUTOSAR CAN Network Management States
The ECU that is developed using AUTOSAR architecture, is having multiple communication protocols. Each protocol is having its own Network Manager to manage the network. So each Communication protocol is having a state machine implemented in the AUTOSAR Network Management module to control the network.
- BUS Sleep Mode.
- Repeat Message Mode (Go To Mode).
- Normal Operation Mode.
- Ready Sleep Mode.
- Prepare Bus-Sleep Mode.
Race Conditions In AUTOSAR CanNM
To avoid the race conditions and state inconsistencies between Network and Mode Management, CanNm will not automatically perform the transition from Bus-Sleep Mode to Network Mode. The CanNm will only inform the upper layers which have to make the wake-up decision. Network Management PDU reception in Bus-Sleep Mode must be handled depending on the current state of the ECU shutdown or startup process.
