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INTRODUCTION
ARINC 429 is the most commonly used avionics data bus in aircrafts. In ARINC 429
data comes at regular interval in a pattern. These data are acquired and recorded in
FDR for post flight analysis. ARINC 429 is suitable where labels are known and
where sampling rate of parameters are known and overall traffic of data is
comparatively less. In case we don’t know which labels are to come and what is the
sampling rate of those labels and data traffic is huge then we can’t use ARINC 429.
But if we want to use ARINC 429 in that situation then we have to use other format of
ARINC 429. These are basically customized form of ARINC 429 specifications.
These formats are:
1.) Sampled ARINC429
2.) Standard ARINC429
3.) Extended ARINC429
These formats have been used successfully in SSFDR for Su-30MKI aircraft. These
formats have been used to receive data from aircraft systems like AHRS, LINS,
ADS, LSS, MFWS, EES, Radar, OLS, ACS, AFCS, RIF and KDLI. Data from these
systems are interfaced through interrupts and acquired in FDR.
DETAILED DESCRIPTION
There are various ARINC 429 channels coming to a FDR. All these channels use
ARINC 429 specifications for communication. Hardware and electrical connections
for all channels are same. But, acquisition of data on these channels is different.
These channels have been divided into above said formats of ARINC 429 based on
nature of data from aircraft systems. The classification of these channels is identified
by the configuration file which is pre-loaded in a memory location in FDR. We can
take a case where total of 20 channels can be identified by their identifier and can be
classified accordingly. Identifiers are tabulated in table 1.
Table 1
Sl.No. ARINC 429 Type Identifier
1. Not used 00
2. Standard ARINC 429 01
3. Sampled ARINC 429 02
4. Extended ARINC 429 03
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All 20 channels are given sufficient resources like DPRAM and RAM so that it can
handle the maximum possible data. In our case it is the Extended ARINC 429
channel which has the maximum data. These 20 channels can be defined as per our
requirement by the identifiers in Configuration file. One instance can be as given in
Table 2.
Table 1
Sl.No. Channel No. ARINC 429 Format Identifier
1. 1 Sampled 02
2. 2 Sampled 02
3. 3 Sampled 02
4. 4 Sampled 02
5. 5 Sampled 02
6. 6 Sampled 02
7. 7 Sampled 02
8. 8 Sampled 02
9. 9 Extended 03
10. 10 Standard 01
11. 11 Standard 01
12. 12 Standard 01
13. 13 Extended 03
14. 14 Extended 03
15. 15 Extended 03
16. 16 Extended 03
17. 17 Sampled 02
18. 18 None 00
19. 19 Standard 01
20. 20 Standard 01
Details of the ARINC 429 formats are described below:
a.) Sampled ARINC 429: This is the most common format of ARINC 429.This is
identified by value 02 in configuration file. These channels are generally at
12.5 Kbps and 50 Kbps rate. In this format data comes at regular interval and
is acquired through scheduler. The labels and sampling rate of all the
parameters are known. Data received is first compared with the labels fed in
Data Match Table and received only after a match of label is found. This
follows the normal format of ARINC 429.
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b.) Standard ARINC429: This is the first customized format of ARINC 429. This
is identified by value 01 in configuration file. These channels are generally at
50 Kbps and 100 Kbps rate. This is used when no. of parameters coming
through channels is lesser. Acquisition is not scheduled but it is interrupt
based. Acquisition is called only when data comes from systems. But, labels
are not fixed. Any no. of labels may come in this format. There is no any DMT
to check for the labels.
c.) Extended ARINC429: This is the second customised format of ARINC 429.
This is identified by value 02 in configuration file. These channels are
generally at 100 Kbps rate. This is used when there is huge no. of
parameters. In this format also acquisition is not scheduled but it is interrupt
based. Acquisition scheduler is called only when data comes from systems.
The vast no of parameters are handled by introducing concept of sets. A
single label can be used for 256 different parameters by using concept of
sets. Details of this format can be described in following points :
1.) Timing frequency of the communication link is 100 kHz.
2.) Data are formed in the way of sets of words with the length of 32 bits.
3.) Each set has its unique value in the band from 1 to 255.
4.) Number of words in a set can be in the band from 2 to 63.
5.) All words in a set are numbered sequentially. A number is given in a way
of a labels in the band from 200 to 277(in octal).
6.) Labels are packed in bits from 1 to 8. The most significant bit of a label
has least value.
7.) A set number is always packed in a word with a defined label, in bits from
30 to 23 including.
8.) Number of words in a set is always packed in a word with a defined label,
in bits from 14 to 9 including.
9.) Data are packed in words with the labels other than label containing set
number and number of words.

We Claim

1. The Different formats of ARINC 429 in Flight Data Recorder, comprising:
- An embedded hardware with at least one processor for running the ARINC 429 channels acquisition executable,
- Relevant memory like Random Access Memory (RAM) and/or Non-volatile Random Access Memory (NVRAM) and/or Read Only Memory for storing program and scratch calculations and/or configuration file,
- A hardware port for uploading of configuration file &
- Respective looms/cables.

2. The system according to claim 1, further comprising of
- A signal conditioner circuit to receive electrical signals corresponding to ARINC 429 data and provide digital data as per ARINC 429 specification.

3. The system according to claim 1 & 2, capable of uploading configuration data to define ARINC 429 channels classification using a communication port.

4. The system according to claim 3, further capable of varying at least one ARINC 429 channel as defined by configuration data.

5. The system as per claim 1 & 2, is not limited to airborne applications alone but can be used on ground/in water.

6. The system as per claim 1 & 2, is qualified as per MIL-STD-810 for working in extreme weather conditions like high temperature, low temperature, vibration, shock, acceleration etc. ,TagSPECI:Refer Annexure-1