Author: Kaarthick Balakrishnan
When a data has to be sent from one Application Software Component( ASWC) to another ASWC which is located in another ECU then we use the Communication Stack. The data is sent in the form of signal in CAN. The signal can have different sizes (Boolean data type will be 1 bit long, int data type can occupy 8 bits in CAN). This data/ signal which has to be transmitted from the ASWC is called the COM signal. For instance, if we consider the seat belt ECU the temperature (signal) is sent from one ASWC to other ASWC in another ECU. The temperature may be sent as a 8 bit data. Hence we may conclude that the data which is sent from the ASWC to the Communication Module through the RTE is called Com Signal.
A CAN signal can have upto 64 bits (8 byte). Now in our case we have used only 8 bits for temperature. The communication module in the AUTOSAR stack will collect all the signals that has to be packed into particular CAN frame ( information will be provided by the arxml file/dbc file which will be loaded ) and send them together as an COM IPDU. The COM IPDU may be considered as CAN frame without the header.
The CAN header will be added by the CAN IF module.