Text preview for : 5990-9139EN Oscilloscopes in Aerospace Defense Debugging ARINC 429 Serial Buses - Flyer c20140828 [2 part of



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Oscilloscopes in Aerospace/Defense

Debugging ARINC 429 serial buses


The Keysight Technologies, Inc. InfiniiVision
3000 and 4000 X-Series oscilloscopes provide
ARINC 429 triggering and decoding, as well as
eye-diagram mask test capability to help you
accelerate debug of your ARINC 429 buses.


The differential 12.5 kbps and 100 kbps ARINC 429 serial Figure 1 shows the display of a Keysight InfiniiVision X-Series
buses are widely used today in a broad range of commercial scope capturing and decoding a stream of ARINC 429 serial
aircraft including many Boeing and Airbus aircraft, as well as bus traffic. All captured words are decoded and displayed in a
future Chinese commercial aircraft currently under develop- time-correlated trace below the captured waveform showing the
ment. Due to the harsh electrical environment of commercial label field decoded in octal, 2-bit SDI and SSM fields decoded in
aircraft, testing the quality of received and transmitted signals binary, and the data field decoded in either hexadecimal or binary
is very important. The primary measurement tool that engineers (user-selectable). In addition, the scope can display a tabular list
and technicians use today to test the signal integrity of serial of decoded data in the upper half of the scope's display.
buses is an oscilloscope. But capturing and measuring the
electrical characteristics of ARINC 429 signals have been a The trigger condition for this particular measurement was to
difficult and tedious process using conventional analog or trigger on words with a label value of 076 (octal). This word is
digital oscilloscopes. Setting up a scope to trigger and shown at center-screen. The next captured word was decoded as
synchronize on specific transmitted or received words often a GAP error word (color-coded in red). Using the scope's timing
requires an external synchronization signal or guessing at a cursors, we can see that time between these two words was less
specific trigger hold-off setting. And then to determine the than the minimum gap time specification of 4 bit times. With this
message transfer information of captured and displayed information provided by the scope, it should now be much easier
communication packets/words requires a commonly used visual for the avionics engineer or technician to troubleshoot the root
"bit-counting" technique, which is slow and prone to errors. cause of this error.

Although ARINC 429 bus monitors/protocol analyzers can
provide the high-level protocol layer information regarding
transfer of data, they tell you nothing about signal integrity.
The answer to this dilemma (scope versus bus monitor) is to
use a scope that is also able to intelligently trigger on and
decode ARINC 429 signals.




Figure 1. Decoding a differential ARINC 429 bus using an Keysight InfiniiVision
X-Series oscilloscope reveals timing and parity errors.
02 | Keysight | Oscilloscopes in Aerospace/Defense Debugging ARINC 429 Serial Buses