Image Processing Reference
In-Depth Information
Application
software
component
Signal
RTE
Signal
AUTOSAR
COM
Diagnostic com
manager and network
management
I-PDU
I-PDU
IPDU
multiplexer
PDU router
I-PDU
I-PDU
FlexRay
TP
CAN TP
I-PDU
I-PDU
I-PDU
N-PDU
N-PDU
FlexRay
interface
LIN
interface
CAN interface
Communication drivers and ECU hardware and communication controller
FIGURE .
Communication software components and architecture.
AUTOSAR identifies three main objects regarding the communication: signal exchanged between
software components at application level, I-PDU (Interaction Layer Protocol Data Unit) that consists
of a group of one or several signals, and the N-PDU (Data Link Layer Protocol Data Unit) that will
actually be transmitted on the network. Precisely AUTOSAR defines:
•
Signals at application level that are specified by a length and a type. Conceptually a sig-
nal is exchanged between application software components through ports disregarding
thedistributionofthiscomponent.heapplicationneedstoprecisea“TransferProp-
erty” parameter that will impact the behavior of the transmission and whose value can
be “triggered” (each time the signal is provided to the MW by the application, it has to
be transmitted on the network) or “pending” (the actual transmission of a signal on the
network depends only on the emission rule of the frame that contains the signal). Further-
more, when specifying a signal, the designer has to indicate if it is a “data” or an “event.”
In the former case, incoming data are not queued on the receiver side while in the latter
one, signals are queued on the receiver side and therefore, for each transmission of the
signal, a new value will be made available to the application. he handling of buffers or
queues is done by the RTE.
•
I-PDU are built by the AUTOSAR COM component. Each I-PDU is made of one or
several signals and is passed via the PDU Router to the communication interfaces. The
maximum length of an I-PDU depends on the maximum length of the L-PDU (i.e.,
DLL PDU) of the underlying communication interface: for CAN and LIN the maximum
