Timing

[Smorth]

Does anyone know how rapidly I can interact with FSUIPC ?

I want to read IRS and ADC values from FS and then send them as ARINC 429 labels to a real PFD. So far i have had an intermittant timimg error and do not know if it is FS or the linking DLL.

Would FSUIPC allow me to read variables at less than 65ms ?

Thanks to anyone taking the time to answer this.

Neil Smorthit

[Pete Dowson]

Does anyone know how rapidly I can interact with FSUIPC ?

As fast as you can switch processes (because that's what happens every time you call FSUIPC_Process), as long as you don't slow down FS so much you lose the point of such interaction.

Each FSUIPC_Process call itself normally takes much less than a millisecond in FSUIPC/FS itself. The rest of the time spent in the FSUIPC_Process call is message queuing, process switching (twice -- to FS and back again) -- plus of course any timeslice that FS uses whilst it has that control you gave it.

If you are running on a multi-processor system, or even a Pentium 4 with "hyperthreading", the timeslice bit probably doesn't apply, so you should see a much faster return.

HOWEVER, the data you are reading isn't really going to be changing every millisecond, unless you are managing to get FS to run at fantastic frame rates. You should be aiming at matching the frame rate -- and to do that, you could do with FS's frame rate being steady.

To get FS to keep a steady frame rate, use its Frame Rate Limiter (Options-Settings-Display-Hardware). Set it to something a bit below the average you normally get. Then time your FSUIPC access cycles to match. e.g. Frame Rate = 20 fps, cycle time = 50 mSecs.

Regards

Pete