Problems with COM-Frequency assignments with FSUIPC

[jonas_llubi]

Hello, 

i am new on this forum so i will shortly introduce myself. 

My name is Jonas and i have a little "Single-Pilot" A320 HomeCockpit with some original modules and some selfmade panels.

For the connection with MSFS2020 i am using MobiFlight and the software "IOCModules" from OpenCockpits. 

 

I have the plug-and-play version of the A320-Radio from OpenCockpits and i am using the "IOCModules" software to use it with MSFS2020. I have the problem that when i change the frequency there for example to 122.805, the frequency on the A320 is 122.800. For a reason the last "5" digit is ignored. I contacted OpenCockpits regarding this and they think, that this is a communication error with FSUIPC. 

 

Maybe some of you know this issue and could help. 

Thanks a lot 

Jonas

[jonas_llubi]

I think it is related to: 

 

[John Dowson]

36 minutes ago, jonas_llubi said:

I have the plug-and-play version of the A320-Radio from OpenCockpits and i am using the "IOCModules" software to use it with MSFS2020. I have the problem that when i change the frequency there for example to 122.805, the frequency on the A320 is 122.800. For a reason the last "5" digit is ignored. I contacted OpenCockpits regarding this and they think, that this is a communication error with FSUIPC. 

What offset are you using for the COM frequency? For COM1, there are two offsets (for the active frequency):
   0x034E:  COM1 frequency, 4 digits in BCD format. A frequency of 123.45 is represented by 0x2345. The leading 1 is assumed.
   0x05C4: Active COM1 frequency in Hz (32 bit int)

For 8.33KHz frequencies, you need to use offset 0x05C4, not 0x034E (as that does not support 8.33KHz spacing). Check which offset you are using. You can also use FSUIPC's offset logging facilities to check what these offsets hold.
You can also check offset 0x0B47 which will tell you which frequency spacing mode is being used (25KHz or 8.33KHz).

There are similar offsets for COM2 and standby - see the Offset Status document for details

5 minutes ago, jonas_llubi said:

I think it is related to: 

Yes, the same issue - but that user was already using offset 0x05C4.

What A320 model are you using?  Check what frequency spacing mode is supported. In the Asobo A320, I see this:
     5469 Monitor IPC:034E (U16) = 0x1870
     5469 Monitor IPC:05C4 (U32) = 118705000
     5469 Monitor IPC:0B47 (U8) = 1

and in the FBW A320 (Development branch) this:
     185610 Monitor IPC:034E (U16) = 0x1870
     185625 Monitor IPC:05C4 (U32) = 118705000

And when I change to 122.805, this:
   450344 Monitor IPC:034E (U16) = 0x2280
   450344 Monitor IPC:05C4 (U32) = 122805000

So FSUIPC is holding the correct values for these aircraft.

Please check those offsets for your aircraft model. If they are holding the correct values, then you need to go back to OpenCockpits. If they are not holding the correct values, then maybe the aircraft isn't setting the COM ACTIVE FREQUENCY simvar correctly. You can either report this to the aircraft developer, or check to see if they use an lvar to hold the correct 8.33KHz spacing - if so, you can add this lvar to an offset and use that.

Cheers,

John

   

 

[jonas_llubi]

Hi @John Dowson

thanks a lot for your detailed informations. I will check that asap. I also think that FSUIPC stores the right data. How can I read the offset values in the logging? 
 

Thanks a lot! 
 

Jonas

[John Dowson]

4 minutes ago, jonas_llubi said:

How can I read the offset values in the logging? 

As I  said, using the facilities provided (Log->Offsets).

Please read the user manual!

John

[ark1320]

12 hours ago, John Dowson said:

You can also check offset 0x0B47 which will tell you which frequency spacing mode is being used (25KHz or 8.33KHz).

John, When and how are offsets 0x0B47 and 0x0B48 updated in order to indicate the current com frequency spacing? Is there a way to force those offsets to update? For example, GPS units often "contain" the Com radios, and you can select the number of frequency digits to be used. If after loading the plane you switch the number of frequency digits, do you have to manually update offsets 0x0B47 and 0x0B48?

Thanks,

Al

[John Dowson]

13 hours ago, ark1320 said:

When and how are offsets 0x0B47 and 0x0B48 updated in order to indicate the current com frequency spacing?

They do not indicate the current com frequency setting, they indicate if the avionics in the current aircraft support 8.33 or 25 KHz, and will be set when the aircraft is loaded.

John

[ark1320]

5 hours ago, John Dowson said:

They do not indicate the current com frequency setting, they indicate if the avionics in the current aircraft support 8.33 or 25 KHz, and will be set when the aircraft is loaded.

John

Yes, that's what I meant by the current com freq spacing  (channel spacing) --  8.33 or 25 KHz. 

Thanks,

Al