For Orion Exploration Flight Test One (EFT-1), the unit-under-test for flight software verification has been chosen as the entire integrated flight software load. At the time of this reporting, the unit test tool, while powerful, operates on very small units, usually classes. This leaves a sizable gap between unit testing and verification. Orion flight software is divided into ARINC 653 partitions, and partition level testing is in this large gap.

PLATO is a test platform that allows testing of software partitions at the partition boundary, called sampling ports. It runs unmodified flight software binaries while providing access to the sampling port inputs and outputs. The PLATO platform is the environment that allows software systems engineers to perform critical testing on their partitions in order to gain confidence and fill the gap between unit tests and integrated flight software testing. PLATO provides display and scripting environments to develop tests and execute them.

PLATO utilizes several pieces of Orion flight software (FSW) configuration data as input to its configuration. The goal is to be able to configure PLATO to run with new FSW within minutes. This is accomplished by using standard build products from the FSW development process.

PLATO consists of several components that execute in a variety of environments. The Script Engine and PLATO TTNet interface run in the Linux environment, along with Simics, which is a software emulation of the Orion flight computer. Simics runs the Orion FSW along with a test harness called HOMER (Host Operated Memory Examination and Replacement). The TTNet provides the communication and synchronization mechanism between these two environments. User displays are served from a Linux workstation to the user’s Web browser.

Recently PLATO has been installed on the verification test benches to increase the level of automation in the verification process. Many verification tests are being updated to run with PLATO and will be used in an automated regression test suite. These tests will allow software systems engineers to increase confidence in incremental flight software updates as the program approaches its first launch.

This work was done by Steve Mueller of Johnson Space Center; Nathan Uitenbroek, Christopher Cox, Jennifer Ha, Eric Vineyard, Peter Vu, David Soto, Melissa Arriola, Carlos Pagan, Christopher Motl, Andy Klausman, Benjamin Peterson, and Johnathan Burke of L3 Communications; and Mathew Benson, Ephram Rubin, and Christopher Couch of Odyssey Space Research. For further information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-25377-1

Software Tech Briefs Magazine

This article first appeared in the September, 2014 issue of Software Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.