Independent Test Capability (ITC)ITC Synchronous Bus (ITCSB)

1553 and SpaceWire Interception

Justin MorrisSteven SeegerBrandon BaileyScott ZemerickMark Pitts

Jeff JoltesJustin McCartyDan NawrockiGary CarvellPeter Medley

ITC Team Members

Contact Us: ivv-itc@lists.nasa.govInternal Website: http://itc.ivv.nasa.gov

External Website: http://www.nasa.gov/centers/ivv/JSTAR/ITC.html

Agenda

• ITCSB Description• ITCSB Features• ITCSB Interception• Current Use– Demonstrations

• Conclusion

NASA IV&V Facility Independent Test Capability 2

ITCSB Description

• Re-usable communication mechanism– Ensures consistent and correct data passing

among distributed simulation components

• Provides synchronization between distributed applications

• Flexible and extensible design– Can be extended to incorporate any

communication protocol

NASA IV&V Facility Independent Test Capability 3

ITCSB Features

• Transport agnostic• Cross platform C++ implementation• Robust User API• Specialized Layers:– MIL-STD-1553B– ESA SpaceWire– Time Sync

• Dynamic interception allows data manipulation – Without modification to software

NASA IV&V Facility Independent Test Capability 4

ITCSB Interception

• Dynamically added and removed• Priority-based• Block, pass, and modify data– Fault injection– Bus monitoring

• Available utilities– 1553 Interceptor GUI– SpaceWire Interceptor GUI– Various command line utilities

NASA IV&V Facility Independent Test Capability 5

Development & Interception

• ITCSB used to create simulation components– Useful for easy integration into simulation environment– Common libraries guarantee communication correctness

• Interception can come later– Development can occur without any consideration of interception– Dynamic nature of interception means it can be used later without

modification to simulation component

• Interception is future-proofing– Any work can be done later without modification to code– Code can be augmented by insertion of interceptions on the

network

• Development of interceptors separate from components

NASA IV&V Facility Independent Test Capability 6

Data Flow With Interceptor

Interceptor Modifying Data

Interceptor Blocking Data

ITCSB Interception

NASA IV&V Facility Independent Test Capability 7

Node A Node BITCSB

Interceptor

Normal Data Flow

ModifyBlock

Current Use

• GPM Operational Simulator (GO-SIM)• JWST IV&V Simulation and Test (JIST)

Environment

NASA IV&V Facility Independent Test Capability 8

ITCSB is the Main Communication Hub within GO-SIM and JIST

NASA IV&V Facility Independent Test Capability 9

NASA IV&V Facility Independent Test Capability 10

NASA IV&V Facility Independent Test Capability 11

Conclusion

NASA IV&V Facility Independent Test Capability 12

• ITCSB provides– Communications backbone for future simulation development– Synchronization for distributed simulation components

• Mitigates timing concerns

– Interceptors that allow the changing of data without modification to software under test

• ITCSB interception is the most beneficial feature for the IV&V analysts– Provides mechanism for fault injection– Allows for testing scenarios that are often impossible with

hardware