16
votes
Accepted
Why use different data bus for civil and military avionics?
There is actually quite a lot of difference between ARINC-429 and MIL-STD-1553. They are different because they were developed by two different groups with different needs.
Both started in the ...
- 19.4k
8
votes
Accepted
What is the encoding difference between ARINC 429 BNR and BCD formats?
Your basic decoding strategy looks correct -I didn't double-check the values, but the logic is sound. Note, however, that the difference of BCD vs two's-complement is not the only difference between ...
8
votes
Accepted
What is the Scaling Factor in ARINC 429?
In the example you pasted, the value $1.5_{10}$ is being sent, which has binary representation $1.1_{2}$. The data is sent as an unsigned integer so some kind of multiplier needs to be applied. The ...
- 96
6
votes
Accepted
How are the BNR and BCD data formats identified in an ARINC-429 message?
The receiver has to be programmed. It's important to remember that A429 is a unidirectional hard-wired bus with a single transmitter and multiple receivers. Each connection is physically unique and ...
- 19.4k
6
votes
How to decode ARINC 429 data?
ARINC 429 is a defined standard that not only describes the packet structure (32 bits) but also the data formats for different labels depending on the equipment ID. To know how to properly decode an ...
- 2,543
6
votes
Accepted
In the ARINC specification, why is baro altitude (label 204) measured in Knots?
It's an error. Attachment 2B does show that label 204 from the GNLU (Equip ID 056) and GLU (Equip ID 060) as being in knots (highlighted below). That is not correct, it is a BNR in feet as shown for ...
- 19.4k
5
votes
What is the Scaling Factor in ARINC 429?
The example given is a bit strange in that it explains how to code a specific value as the scaling factor changes. In using A429, we don't often think in terms of how the scaling factor modifies the ...
- 19.4k
4
votes
In ARINC 429 where are the bits indicating the hex value of Equipment ID?
ARINC 429 is a unidirectional one-to-many (broadcast) transfer bus with a maximum of 20 receivers.
SourceDesign with four unidirectional ARINC 429 buses
There is normally little need to identify the ...
- 70.9k
4
votes
How many labels are defined in ARINC 429 for calibrated altitude?
There is no defined "calibrated altitude".
The following are all altitude related labels:
102 Selected Altitude,
107 Selected Cruise Altitude,
120 Range to Altitude,
127 Selected Landing Altitude,
...
- 51
4
votes
Accepted
What is the difference between Body Pitch Rate and Inertial Pitch Rate?
I'm not 100% sure about ARINC definitions specifically, but in the general aeronautics usage the inertial frame is the ground (flat Earth) frame. The rotation from this inertial ground frame to the ...
- 9,013
4
votes
How different is ADFX/ARINC 664 router from normal Router?
The point of ADFX/ARINC 664 is that it is real time. That means the switch guarantees each type of message will be delivered in specified time according to its priority and allocated bandwidth.
For ...
- 56.2k
4
votes
Does the civil industry use the CAN FD bus?
It's hard to prove a negative, but I would say the answer is no for the following reasons:
In all my years in the avionics industry, I've never heard of anyone
even discussing the possibility (though ...
- 19.4k
3
votes
Accepted
What is the purpose of the selected altitude/airspeed in ARINC 429?
Both labels are used to transmit the altitude and airspeed that are dialed into the Mode Control Panel of the autopilot. They are not necessarily the current altitude/airspeed, instead they are the ...
- 82.8k
3
votes
Accepted
How to set frequency and distance in ARINC 429?
The first thing you need to understand is that DMEs are not tuned by their actual frequency but by the frequency of the paired VOR/VHF Com, ILS, or MLS frequency. For the vast majority of operations, ...
- 19.4k
3
votes
Accepted
How to encode an altitude in ARINC429?
From ARINC 429, Attachment 6:
Label 025, Selected Altitude (BCD)
Five binary coded decimals. Range is up to 50000. Resolution is 1
foot.
Bit 29 (MSC) ------------------------------ Bit ...
- 19.4k
3
votes
Is it possible to communicate an everyday computer with the ARINC bus?
Is it possible to communicate an everyday computer with the ARINC bus?
Sure. there are appropriate controllers to be plugged in a slot - or even as USB, like the one you found. After all, basic USB ...
- 555
3
votes
In the ARINC specification, does "sig bits" include the sign bit?
In A429 BNR words bit 29 is the sign bit. Individual label descriptions are not entirely consistent in that many will identify bit 29 as part of the sig bits field.
In any case it's important to look ...
- 19.4k
3
votes
Accepted
Are the discrete I/O considered to be part of the ARINC interface?
It depends on which ARINC document you're talking about. ARINC 429 is a digital serial bus standard. Discrete data may be sent in ARINC 429 data words, but that's just bits in a word not the physical ...
- 19.4k
3
votes
Numerous questions regarding ARINC429 protocol
Resolutions in the A429 spec are approximate, so calculate them yourself.
Resolution = Range / (2^significant bits)
Here is one way to do it:
Load your 32 bits into a signed 32-bit integer.
Shift ...
- 71
3
votes
Accepted
Does ARINC 429 have any error correction methods?
There are no error correction methods defined a the base A429 layer. As you noticed, words with an incorrect parity bit are often simply ignored by a receiver.
At application level, additional logic ...
- 335
2
votes
What is the Scaling Factor in ARINC 429?
The mistake I think the link is making is that number of significant bits determines the position of the LSB. The scale factor can influence the necessary number of sig bits, but the desired ...
- 2,543
2
votes
Accepted
What is the criteria for selecting BNR or BCD as data encoding in ARINC429
The general ARINC guideline for publishing data is to publish both BCD and BNR values when both types are defined. That allows the receiver of the data decide which to use. If only one form exists, ...
- 19.4k
2
votes
Accepted
Why apply resolutons in data words for ARINC 429 bus
The ARINC 429 Word resolution tells you what value the LSB corresponds to. You can also tell what the resolution should be by looking at the Range and Significant Bits.
It doesn't describe the actual ...
- 2,543
2
votes
Accepted
What are the major aircraft systems (LRUs) using the ARINC429 Protocol?
On modern aircraft all equipments that needs to communicate to each other in binary format may use ARINC 429 protocol. For instance all fly by wires computers on Airbus 320, 330, 340 use arinc 429 ...
- 1,762
2
votes
What is the purpose of the selected altitude/airspeed in ARINC 429?
DeltaLima very nicely covered the "what" of these labels. As to the "why", I have three examples of their uses:
Autopilot setpoints (altitude, airspeed, heading) are displayed on the Primary Flight ...
- 4,640
2
votes
Does ARINC 429 have any error correction methods?
You wouldn't correct the ARINC 429 label, but simply ignore that transmission and wait for the label to be resent again.
If the label isn't received properly within the defined period it would be ...
- 2,543
2
votes
How to identify transmit labels for a particular equipment in ARINC429?
As Gerry mentioned in their comment, the equipment ID label (377) indicates to the receiver how to decode the labels being received on that ARINC 429 channel.
The transmitting equipment (Tire Pressure ...
- 2,543
2
votes
What is the format for standard ARINC 429 labels with 20 sig bits?
The extra bits of precision would use the SDI bits as you've suggested.
From ARINC 429 Part 1 dated May 17th 2004
2.1.4 Source/Destination Identifier
Bit Numbers 9 and 10 of numeric data words ...
- 2,543
2
votes
What could cause an air data computer interfaced via A429 to only display integer values?
Not sure what rate the IFD 550 expects the transmit rate to be, but from what I can find on the Shadin 2000, it's label transmit rate is configured by a switch position and can vary from 50,100, or ...
- 2,543
1
vote
USB interface for FDR?
Certified FDR's for commercial aircraft don't have USB ports. They have interface ports because you obviously need to be able to extract data, but they are usually proprietary and each one uses a ...
- 12.6k
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