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Arinc signal?

rv9aviator

Well Known Member
I have a trutrak autopilot with GPSS steering capabilities but only have an SL-40 Com radio at present. I need to send an ARINC signal to the EFIS-Autopilot in order to be able to be able to intersect a waypoint without overshooting and correcting back to the new course. Is there a less expensive way to do this than buying an SL-30 nav com radio? I am not looking for ILS features or information for IFR flight just additional autopilot features with my TruTrak autopilot. Thanks
 
Do you have an EFIS???

My A/P is hooked to the EFIS, and not to the SL 40.

I can not think of a reason to connect the A/P to an SL 40.
 
Yes I have a TruTrak EFIS, but in order to get an ARINC signal and not just a simple serial signal from my GPS I would need something like an SL-30 or 430 nav-com instead of my SL-40 which will output the ARINC signal.
 
An SL-30 doesn't output ARINC, only serial. To use the GPSS you either need a box like a 430 or an EFIS that does internal conversions.

Bob
 
My EFIS---GRT has an add on ARINC plug in module.

Maybe your TruTrack has one available too??
 
I was misreading the installation manual on the TruTrak Efis. The SL-30 serial output only adds NAV information to the EFIS Screen. It looks like the cheapest way out to get ARINC output is a Garmin 155XL, 200XL, or 300XL. Thanks for the info about the SL-30.
 
I think you're confusing two things.
ARINC is a digital standard that is used for some communications between avionics.
GPSS is "GPS-Steering" which is a signal which advises to start turns before a way point, to make the turn smooth with no overshoot.

GPSS signals are usually sent over ARINC lines. But not all ARINC signals have GPSS included.

I have a GRT HX, and it will send ARINC signals to the autopilot (I have a Trio) but it will not send GPSS signals unless it is also hooked up to a GPS like the Garmin 400W, 420W, or 430W, from which it actually gets the GPSS commands.

I don't know if the Garmin 300 radios send GPSS signals, or not.
 
According to the TruTrak manual there are pin outs on the 155, 200, and 300XL for ARINC signals. TruTrak does offer an ARINC converter but you still have to be connected to something like a 430. I think the converter just adds other features like VOR/ILS/LOC besides the GPSS steering.
 
I think you're getting closer. ARINC has support for a large number of data tags but not all of them are used by any given system at a given time. For example, on a 430W you can set ARINC output for VOR/ILS but that's simply sending that info out digitally (similar to what an SL-30 is doing with its seral out). You can also set the 430W to send GPS data in a variety of formats on the ARINC ports.

The EFIS systems to a varying degree ingest navigation/GPS data and then output it to the autopilot using ARINC. ARINC supports a richer set of data tags than the serial protocol which allows for turn anticipation, etc. The serial protocol essentially just sends a flightplan and position, and when the AP receives that data it will fly to the next waypoint and then turn to the next waypoint. So, the preferred way for an EFIS to communicate with the AP is via ARINC. Some EFIS systems will take nav data in and convert that internally to GPS Steering (GPSS) commands and then output that to the AP via ARINC. I'm hesitant to take a stab at what each EFIS brand does or doesn't do since it's a fast changing market. I know that GRT does this since I had a triple HX setup along with a TT AP, 430W and SL-30 in my last plane. Some other brands do this also but some don't.

As anothe poster said, you need to treat this as 2 different things - you probably want the ARINC interface for the EFIS since that allows the EFIS to communicate with the AP using GPSS (turn anticipation is a benefit). Communication with external navigation devices and what additional capabilities you'll get by doing that with ARINC will be EFIS dependent.

Hope this helps a little.

Bob
 
Speak to Trutrak

Jim,

I think the best thing you can do is pick up the phone and speak to Lucas at Trutrak. Explain what you have, ideally what you would like to be able to do and how much money you are prepared to spend and Lucas will advise you what your best options are.

Regards,
Steve
 
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