Abstract:
Deos includes an industry standard lightweight TCP/IP stack (LwIP) with a DAL-A sockets library so it can provide data transport during in flight or on ground as part of its standard package. While it may have high data integrity (e.g., through CRC or other such mechanisms), TCP/IP over Ethernet is a non-deterministic protocol. As such, it is not suitable for avionics applications that require determinism or high robustness. In contrast, there are several are several redundant and deterministic data network technologies such as ARINC-664/AFDX, time triggered ethernet (TTE), and time sensitive networking (TSN). These interfaces are based on switched Ethernet technologies and can include system redundancy such that they are applicable for aircraft data network applications. Their feature set enables them to be used as a digital backbone for aircraft control and other applications where both integrity and availability are essential. Each of these solutions generally requires specific end point hardware to implement the protocols in firmware in order to meet the required communication timing and throughput. The implementation of the software device drivers for these technologies on Deos can leverage Deos' I/O Infrastructure (IOI) data distribution service for data decoupling. IOI is a DO-178 DAL-A module that can distribute data based on XML configuration files that specify the data paths, access control and optionally data formatting. It implements an inter-partition communications data interface between avionics applications including ARINC-653 partitions using the ARINC-653 APEX API sampling/queueing ports. Together, these features allow developers to readily adapt to changes in communication structures all through XML configuration files, versus recompiling which would impact the verification evidence of the module. This paper will talk about the different networking standards and how the use of Deos' IOI provides a way for the system to easily adapt to different network configurations without causing the driver library or end application(s) to be modified and thereby minimize change impact for reuse/reverification.