FSX 737 N1 reference and autopilot N1 hold selector

[bobs101]

I want to ask does anybody know something about N1 reference and autopilot N1 Hold selctor offsets and when they will be supported by FSUIPC. So far I couldn't find any way to access these variables. The closest i found is autopilot rpm value and rpm hold but the reading and writing these addresses doesn't seem to have any effect on the default boeing 737 in FSX.

For information - I am using full FSBUS hardware set and i am having really hard times trying to assign MCP functionality to it!

[Pete Dowson]

I want to ask does anybody know something about N1 reference and autopilot N1 Hold selctor offsets and when they will be supported by FSUIPC.

They weren't available (or at least apparently not working) in FS9 or before, and since FSUIPC is primarily about compatibility with previous releases rather than support for brand newly-programmed applications they didn't get automatically supported for FSX.

I have been adding stuff by request -- it is just that no one requested these before.

The closest i found is autopilot rpm value and rpm hold but the reading and writing these addresses doesn't seem to have any effect on the default boeing 737 in FSX.

You are looking at the wrong document. According to the FSUIPC4 Offsets Status document the A/P RPM hold variable is possibly readable at 07FA (FSUIPC4 does read it into that location), but there's no way to set it through those offsets, and that is documented too. In the pre-FSX "FSUIPC for Programmers" document the relevant offsets (07F4 and 07FA) are just marked with queries, and as far as I am aware never worked.

However, FSX does have these Controls for N1 hold:

AP_N1_HOLD

AP_N1_REF_SET

So if these do equate to the Variable names "RPM HOLD" and "RPM HOLD VAR"" (do you confirm that?), then I could add support for both reading and writing these via offsets 07F2 and 07FA.

Could you verify first that they work? You can assign them to keys or buttons (the "SET" one needs a parameter of course). You could also use the controls via offset 3110.

There are also controls AP_N1_REF_INC and AP_N1_REF_DEC.

Unfortunately, you just missed an opportunity for these to be added -- if you had asked me before the weekend I could have added support into the just-released version 4.28. I'm not too tied up to do it until I return from holiday -- in the week commencing 19th May

For information - I am using full FSBUS hardware set and i am having really hard times trying to assign MCP functionality to it!

But surely the standard 737 MCP doesn't have an adjustable N1 facility. The "N1" (THR) button is normally programmed to do the same as TO/GA, as both use the relevant N1 value set via the CDU. That's certainly how Project Magenta has always treated it.

Let me know and I'll add stuff to my list.

Regards

Pete

[bobs101]

Hello Mr Dowson,

Thank you very much for this quick response, I really appreciate it!!

Well, I did some tests after your reply and here is the situation:

The commands AP_N1_HOLD, AP_N1_REF_DEC, AP_N1_REF_INC, AP_N1_REF_SET - they all work fine and do exactly what they should do - I checked them trough offset 3110 with fsbus.

With the other offsets I just went crazy because whatever I did, I couldn't extract anything different then zeros, using both ways - with fsbus and FSInterrogate2std.exe and cycling trough all possible situations and airpanes in FSX.

So these are the offsets that I was trying to read:

07FA, 07F4 (as you referred and as they are in the documentation) and offset 07F8 which I found marked in FSInterrogate as "AP RPM Value (?)". Anyway - from all 3 offsets I read only zeros all the time with no matter what I change in FSX. May I kindly ask you to check what's wrong with them - when you have time of course, its not an emergency :).

Anyway - I can continue using offset 3110 to manipulate them, but it will be great if there is a way also to read the n1_hold button status and n1_ref value.

Thanks again and best regards

Boris Staykov

[bobs101]

Uh, sorry, I just payed attention on this: "In the pre-FSX "FSUIPC for Programmers" document the relevant offsets (07F4 and 07FA) are just marked with queries, and as far as I am aware never worked."... I was so excited before that I missed that and I was wandering why they don't work on FSX... :).

[Pete Dowson]

The commands AP_N1_HOLD, AP_N1_REF_DEC, AP_N1_REF_INC, AP_N1_REF_SET - they all work fine and do exactly what they should do - I checked them trough offset 3110 with fsbus.

Okay.

07FA, 07F4 (as you referred and as they are in the documentation) and offset 07F8 which I found marked in FSInterrogate as "AP RPM Value (?)". Anyway - from all 3 offsets I read only zeros all the time with no matter what I change in FSX. May I kindly ask you to check what's wrong with them - when you have time of course, its not an emergency :).

Well, 07F4 isn't implemented at present in FSUIPC4 in any case, as it didn't work in FS9 or before. I can add it, assuming that the Sim Var for "RPM HOLD" works and equates to "N1 hold". Should it?

07FA should actually read the A/P RPM Hold value -- it is definitely reading this from FSX -- but I have no idea what units these would be in -- what units do the AP_N1_REFcontrols use, please? In other areas the N1% value is from 0 to 16384, with 16384 being 100%, but maybe these are different?

If the data file for FSInterrogate has 07F8 down for RPM value then it is an error. I'll check it and change it.

Anyway - I can continue using offset 3110 to manipulate them, but it will be great if there is a way also to read the n1_hold button status and n1_ref value.

If these do equate to the AP RPM hold and AP RPM values then they should certainly be readable, and the latter should be in 07FA already. If they don't work I'm afraid there's no way. I'll check them.

Regards

Pete

[Pete Dowson]

May I kindly ask you to check what's wrong with them - when you have time of course, its not an emergency :).

...

Anyway - I can continue using offset 3110 to manipulate them, but it will be great if there is a way also to read the n1_hold button status and n1_ref value.

Okay, I've checked into this.

I can make offsets 07F4 and 07FA work, for both reading and writing. The writing of 7f4 to turn the N1 hold on/off will have to use the FS control, internally, and that's only a toggle, but it will check the last read value first.

The N1 hold value can only be set directly in whole numbers, 0 to 100% or more, even though you'd normally have values at least ot 1 decimal place, so I'll make the 07FA value readout more accurately, with 16384 = 100% as it already does in the Engine read-outs.

Unfortunately, the only way to set the value directly is via the FS control, so writing to 07FA will actually write the nearest whole % number.

All this is easy enough for me to do and it will be in the next incremental release, on my return from holiday in three weeks.

Regards

Pete

[bobs101]

Thanks a lot! Actually the more important is to have way to check the status of the N1 hold button (on/off) and the actual value of N1 hold in % is not so interesting as far as i can just simply increment or decrement this value. And i am pretty sure that the "autopilot rpm hold" is the same as "n1 hold" but it must be checked anyway...

Thank you very much again for all the answers and have a nice holiday!

:)

Best regards

Boris Staykov

[Pete Dowson]

Actually the more important is to have way to check the status of the N1 hold button (on/off) and the actual value of N1 hold in % is not so interesting as far as i can just simply increment or decrement this value. And i am pretty sure that the "autopilot rpm hold" is the same as "n1 hold" but it must be checked anyway...

I found a bit of time to make the small changes needed and test them, so please download FSUIPC 4.281 from this link:

http://fsuipc.simflight.com/beta/FSUIPC4281.zip

Offsets 07F4 and 07FA should now work fine, reading and writing.

Regards

Pete

[bobs101]

Waw, thanks again, that is great! I'll test everything today and by tonight i'll post the results!

Best regards

Boris Staykov

[bobs101]

Yeees!!! They work perfect - reading and writing!!!

Thanks a lot Mr. Dowson, this is a great thing!!!!

Again - have a nice holiday and sorry for bothering you with this thing, I hope it will be also useful to all other flightsim enthusiasts!

:)

Best regards

Boris Staykov