AIT ARINC 429 Add-On Feedback

[StephenB]

Great! Glad it is appreciated. I know you asked for the SDI feature a long time ago.

Unfortunatley, there is no export function at this time. Good idea though

[skadilover]

Hi,this CustomDevices seems not support "Block" and "Acyclic" type.However we wanna program via Veristand with C#,so we need to use AIT429  as same in CustomDevice as in AIT Driver provided by AIT.Could you give me some help or advices?

[hrobitaille]

Hi,

For the Acyclic type,  perhaps the Disable channel could be used as a workaround.

Regards

[skadilover]

Thanks for your advice,however it`s maybe not a good idea,because we must consider the factory of effiency.

[kabooom]

Hi !

At first, i'm quite new with ARINC 429 protocol (so apologize if my questions seems to be stupid).

We planned to use AIT 429 board and corresponding VeriStand Custom device. I have a few question :

1) If i'm right we need to use AIT Flight simulyzer software to generate the xml file which will be loaded by VeriStand Add on. I tryed this software, it seems you can only define the channels and the labels. The data inside the label can not be defined in this software. You have to define the data parameters in veristand after importing the database. It seems you can modify the xml  generated and add manually the data in the xml... All this is a little bit complicated, i cannot understand why you need two differents tools to define the database.

2) In ARINC 429 there is 3 different encoding type : BCD, BNR and DSC, there is no way in the custom device to define the encoding type for each data. Is it possible to use BCD encoding wih this custom device ? If yes how ?

4) Is it possible to modify the SDI of a channel during the transmiting?

5) An improvement: The custom device doesn't check any data overlapping or if the data are defined outside the range (it is possible to define a start bit of -1...)

6) Is there any performances test of this custom device? I read legacy board may occasionally suffer brief period of poor performance if using a large buffer size ..... 

[StephenB]

Hi Kaboom!

Lets see if I can help:

1. Correct. Unfortunatley the tool from AIT does not go as far as defining parameters, so we had to put that functionality into the custom device.
2. Since there are a bunch of different ways people use the label data, the custom device provides direct access to the label data by start bit and bit length of a defined parameter. You can have multiple parameters per label and they can even overlap and contain linear scaling. So you can do whatever you want with the label data.
3. .
4. Yes. When defining your output label parameter(s) just include the bits that are for SDI
5. Overlapping is purposefully not prohibited as there is some use case there (at least for input). I thought I put in range limits to prevent start bit of -1. Can you screenshot that?
6. The performance should be good but I have not personally benchmarked with many labels on many channels. I do raw reads of the channel's buffer instaed of a single read per label so the overhead of adding additional label reads is very low. Adding additional channels does mean more channel buffer reads though so that should increase CPU usage some. Each label write is also an individual call so those are more expensive than reads. The legacy performanc blip was a bug in the legacy driver that is no longer supported anyway.

[kabooom]

Hi Stephen,

Thanks a lot for your answer, it will surely help! I also post the same thing in veristand forum (i didn't know if somebody will help me...) sorry !

It still  one thing i'm not really sure (certainly because a lack of knowledge). It's about the encoding of the data in the label. For example if in the same label, i have 2 data, one encoded in BNR and the other one in BCD. I will get 2 veristand channel. After that in order to get the correct corresponding physical value, it means i wil have to decode the raw data for example using a veristand calculated channel ? 

[hrobitaille]

Hi Kaboom,

I am using the AIT Custom Device. You don't need to use calculated channel. The CD decodes the data regarding the parameters that you have associated to your channel : Start bit, Length, Offset, Scale and Sign.

[hrobitaille]

HI,

Is there a way to detect if we not receive new message on a Rx link ?

When a link is down, the Custom Device returns the last read value.

I was looking the information in the staus section but I am not able to understand them. The Inputs Loop Duration displays 0 or 1 permanently (the Read Rate is set to 100 Hz). The input Late Count can be different of zero but I didn't understand in which condition this count is increased.The Outputs information are always 0.

Regards,

Hubert

[StephenB]

Unfortunately the custom device does not support this. Ideally, it could have "label information" channels for all label inputs similar to the way the XNET portion of NIVS works. These would say a timestamp of the last label received and a time difference between the last two receptions.

I can add this to a list of requested features, however, given my current schedule... it would likely be faster to add the code yourself.