IMA Flashcards
problems with cassical / federated avionics
- crosslinking to add new system
- supplier making hardware and software (not specialist in both)
- a lot of diff hardware and software on aircraft that is proprietary. -> high mantenence effort.
- cross-computer links and proprietary -> diff for maintenence
- hardware and software no abstractino -> more expensive with obsolescnce (can have to requalify system)
- supplier insentive to ned to do maintenence
goals of IMA
- reduce number of controllers
- reduce obscolencence costs via OS
- standard API for all software
- standard hardware platform. (reduce maintenance costs. )
what is IMA?
integration of software onto shared hardware
describe the IMA cabinet concept? (beoing)
common computing resource is cabinet
chassis with backplane data bus and
CPM (computer processing unit with Ram, CPU, application software)
power
IOM (input output modules)
IMA cabinet concept advantages
- strictly modular and scalable (maximum modularity and scalability)
- easy to replace module (each hardware is LRU - line replacable unit) to it is heavier
- can have third party IOM
- reduce CPU needs to do redundant signal procesing
(addidional delay on backplane bus)
what does a B-777 IMA cabinet (CCR -common computing resource) contain
2 x cabinet switch
8 x general processing module
2 x graphics generator
2 x power conditioning unit
what does the AFDX topology contain for the IMA cabinet concepts
2 x CCR common computing resource
6 x remote switches
21 x remote data concentrators
what are the components of the Integrated LRU IMA Platform
CPU board (CPU and RAM including software applications)
power board
I/O board (signal processing -data busses, analog, discrete)
all in a metal housing
CPOIM communication
- CPIOMS communicate via AFDX network
- board communicate via USB (airbus EYY) or PCI (thales deihl)
CPIOM advantages
powerful CPU-> up to 23 apps
compact and lightweight
can build various kinds of CPIOMS
CPIOM disadvantages
- if board breakes, entire LRU needs to be replaced.
- moderatey scalable
- 3rd party I?O requires qualification of entire CPIOM
- high deegree of CPU/ I?O integration effort
what are the seven CPIOMs and what do they do?
what else links to ADCN
CPIOM A - pneumatic B - Aircon C - cockpit and flight controls D - air ground data link E - electrical F - fuel G - landing gear
IOM -for IO without AFDX connection
who builds each CPIOM
airbus EYY -> C, D,
Thales Deihl -> A, B, E, F, G
THales Deihl supplies OS for alles
what does a CPIOM contain?
- firmware
- OS
- config tables
- system applications
- ATAxx applicatinos
what does firmware do?
makes CPIOM operable
- to load OS
- basic data loading
what is OS job
- separate hardware + software (abstraction -> good for obsolescence)
- partitioning (OS has DAL of highest user -> separates user time so they can each have lower DAL runnning on same OS)
- ensure segregation of OS from applications (scheduling, mom managemnet, IO handling)
how is memory organized
-each app has its own memory and own independent access to it
module area
partition area
supervised are
user area
what is NVM and how is it organized
non-volatile memory (won’t erase in no power mode)
each applicatino has some
how is I/O handled?
The OS stores io data in driver lanes
samples are updated either via sampling (continuous replacement) or queuing (sequential transition)
job of API
makes requests from application to OS resources
describe the OS configuration
what is usage domain
static, determined at time of compile/design (based on many rules)
-verifyed by DO 178 to DAL A (global and local)
usage domain is set of possible configurations
what measures can be taken if bite detects an error?
- error stored in NVM
- software restart
- hardware restart
- LRU shut down and redundant system takes over.
what is additional job of R-BITE
confirm and correlate errors reported by system BITES of IMA resources. Reports to CMS
can get no fault found errors
what are the levels of BITE in IMA
application BITE : software reports to system BITE
System BITE: reports to CMS and RBITE
RBITE: correlates error. Reports to CMS
what is purpose of ISDL and limitations?
IS: monitor resources from outside computer
DL: load software onto coputers
-> slow (must be doen in 15 min bc it is done through OMT which is avionics domain to avionc network (ADCN) and must go through SCI which checks packet wise
what is SNMP and MIB
the checking of errors in translation through AFDX network are stored in MIB (management information base). Small Network Management PRotocol is used to quired results. This is a task of the AFDX Central Network BITE
What is the job of monitoring?
continuously monitors CPIOM functions (memory segregation, watchdog timer, I/O communication hardware errrors.)
reports to BITE.
(does actual checking of functions. BITE reports to CMS and doing of appropriate actions)
what does system supplier normally issue along with system for qualification
Declaration of design and performance. (fully certified system complying with all DO 178
new qualification relationships
see pic
what are the goals for software qualification
- dont have to qualify entire unit
- change of software should not require change of any other software qualification
- independent dqualification
what are prerequisites for goals of software qualification to be achieved
1) segregation of all software even in cases of shared resources
2) even for arbitrary configuration
what is incremental qualification
certify parts of IMA, not whole
what is “usage domain”
set of valid configurations
rules of dependencies of commonly used resources
defines max and min values, dependencies, compiler settinds..
by IMA moule suplier
necessary so others can maek independent software
which document outlines IMA qualification process?
DO 297 -> references DO 178 and DO 254
