arinc429

[SpiekerHoiting]

Hello, is there anybody who wrote code to read Arinc429Word in Visual Basic? I'm programming ECAM screens to run on a network computer as an alternative to Project Magenta. All's going well until I encounter Arinc429Word-vars. I can read the values usins FSUIPC; they're LVARs, as integers. But they should be read as 32 bits binaries I believe.. I'm stuck..

 

[John Dowson]

I don't know anything about Arinc429 (and am not familiar with VB either!) , but you should be able to read  an lvar and convert it to whatever data type you need. An lvar can hold any data type to a maximum of 8-bytes.

What version of FSUIPC are you using, and how are you getting the lvar value? If you are reading as a integer, which I presume is 4-bytes/32-bits, can you not just convert that to a 32-bit binary data type?                                                                                                                                                                                             

[SpiekerHoiting]

Hi John, I use a registered version of FSUIPC7. I read the value through simconnect (fsx_simconnect.AddToDataDefinition(StructDefinitions.Struct1, "L:A32NX_APU_EGT", "", Microsoft.FlightSimulator.SimConnect.SIMCONNECT_DATATYPE.FLOAT64, 0, 61), but now I have to figure out how to translate that to a 32 bits-Binary. Arinc429 is difficult because only part of the 32 bits are data. Other parts are parity(?)/ssm(?)/labels(?)..

[John Dowson]

Ok, so you are using SimConnect, not the FSUIPC SDK. And you are requesting it as a 64-bit/8byte float (SIMCONNECT_DATATYPE.FLOAT64), not an integer/32-bits. All lvars are stored internally as 64-bit floats, but you can covert them to the actual data-type required in your code, but it is up to you to do this. As far as MSFS is concerned, lvars are only numeric - from the SDK documentation:
    IMPORTANT! "L:" vars can only hold numeric data and nothing else, eg: no strings, no binary values, no structs, etc...

With FSUIPC7, you could also add the lvar to a free FSUIPC offset and read it from there (see Advanced User guide for details).

1 hour ago, SpiekerHoiting said:

now I have to figure out how to translate that to a 32 bits-Binary. Arinc429 is difficult because only part of the 32 bits are data. Other parts are parity(?)/ssm(?)/labels(?)..

Well, it is up to you how you interpret/what to do with the value, I cannot help with that. Looking at the MobiFlightt preset that reads this lvar (A32NX_APU_EGT), the description says:

 `Arinc429Word<Celsius>`, The APU's exhaust gas temperature,,when < -273.15 the ECB isn't supplying information, for example due to being unpowered. 

So it looks like they are using a specific datatype/class to handle this.  Maybe better to ask the author of this preset (rofl-er) how to interpret this on the MobiFlight Discord channel.

 

[SpiekerHoiting]

Hi John,

I took a few hours and some help from someone I met on Discord, but I found it!

                Dim u64Val As ULong = s1.SC_APUEGT
                Dim u32Val As UInteger = u64Val And &HFFFFFFFFUI
                Dim rawData = BitConverter.ToSingle(BitConverter.GetBytes(u32Val), 0)

                LabelAPUEGT.Text = (Int(rawData).ToString)

I'm a happy man and can continue!

Thanks for your responses!

 

Greetings,

Harrie Hoiting

[John Dowson]

Thanks for  the update - glad you found it!