IFD540/440 Integrations with Aspen EFDs and ACUs

I don't have a good picture of how these two are wired together, so maybe the following doesn't make sense but here goes. It sounds like the 429 data passes from the Aspen through the ACU or ACU2 if there is one present, and at that point some of the data is stripped off before it is passed along to the IFD540. Presumably there is firmware in the ACU that is doing this stripping function. Isn't there another option where a firmware upgrade to the ACU allows passage of the data of interest? If a software change to the EFD1000 is contemplated as a fix for the resolver data problem, why not change the ACU firmware at the same time if this is needed to allow for the data to pass through to the IFD540 along the common data bus, which seems like the most logical way to do this?

Aspen's IM (Rev. BD), Figure 9-28A now has a footnote regarding Digital Heading Outputs:

Somewhat in reverse logic, does anybody know if it is possible -

What data are you seeing on your IFD540 after the "ACU workaround" that you weren't getting before?

ddgates wrote: If you have an ACU1,  TAS and BaroAlt don't get through.  540 needs those data pieces for winds etc. You won't get selected heading bug on the 540 because the ACU1  doesn't pass that through.

If Mike has had the heading bug displayed on his IFD540, then he must be bypassing the ACU, in the 429 feed to the IFD540. If so then I'm curious why he doesn't have wind vector as well.

I think you want to parallel the ACU1 and the IFD540.

But just for clarity if the ACU1 is feeding something else, say an autopilot, want to maintain its connection.

Bringing this back to life because I don't think there ever was a resolution for getting baro alt from Aspen ACU to the 540. Was suggested that maybe possible to tap pins 26 & 27 off the Aspen to get the info into the 540.

Yes.  What we did was have the shop do a Y connection (parallel), to the ACU and to the IFD.

Well, we could sound off, I'm very happy. Even have the HDG BUG now, on the IFD540.

Edited by oskrypuch - 29 Jan 2016 at 3:10pm

Very happy it works great. 

Essentially yes.

IIRC after you wire this up, the 429 config has to br Honeywell EFIS on the IFD.

Edited by ddgates - 30 Jan 2016 at 7:25pm

That is a lot of $$, unless maybe the ACU is buried somewhere? There is no behind the panel access required, just access to the ACU.

Edited by oskrypuch - 01 Mar 2016 at 3:35pm

I think $400 is reasonable, and I also think it is worth it.

Hi I see on Aspens page that software version 2.9 is now out, or at least they have updated their manuals section to cover release 2.9. Has anyone installed this and can you validate that the VOR line functionality we were discussing on this topic has in fact been enabled? (Aspen resolver output now sent to the IFD540)

I looked at the Aspen documentation which is immediately available re: 2.9, and it mostly speaks to integration with the STEC 55X.  Didn't see any mention of other changes, doesn't mean it's not there - just didn't see it.