Avidyne Homepage
Forum Home Forum Home > Avidyne General > IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
  New Posts New Posts RSS Feed - STEC 55x GPSS fail with IFD 540
  FAQ FAQ  Forum Search   Register Register  Login Login

STEC 55x GPSS fail with IFD 540
 Post Reply Post Reply
Author
Message
  Topic Search Topic Search  Topic Options Topic Options
rolfe_tessem View Drop Down
Senior Member
Senior Member
Avatar

Joined: 06 Jan 2012
Location: Massachusetts
Status: Offline
Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Topic: STEC 55x GPSS fail with IFD 540
    Posted: 14 Oct 2022 at 3:45pm
I just had my avionics shop install a Shadin ADC-200 (yellow tag) to enable air data on my IFD-540. The HSI is a King KCS-55A. I thought everything was working on the test flight -- the air data definitely works -- but now I'm getting GPSS "fail" on my STEC 55X when I try to enable GPS steering.

Before I just toss it back in the avionics shop's lap, where should they be looking for the culprit -- at the HSI end of things or at the IFD end? The STEC works fine in other modes, HDG, ALT, etc.

I'm hoping this is just some parameter or speed mis-match but maybe someone here has some experience with something similar. I've opened a ticket with Avidyne but haven't been able to get back to the airport to download logs yet. I've emailed STEC support, with no response.

Thanks for any pointers!

Rolfe
Back to Top
PA23 View Drop Down
Senior Member
Senior Member


Joined: 12 Oct 2019
Location: MMU
Status: Offline
Points: 304 		Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2022 at 3:55pm
I'm using an S-Tec 60-2, which means I have an external GPSS steering converter, the S-Tec 55 I believe incorporated it internally.

If I am correct the GPSS steering module can accept either serial or ARINC 429 for steering information, mine is using ARINC 429, the setting for me is on the "Main ARINC 429 Config" page, I have "Out 1" speed is set to "Low" and Data is set to "GAMA 429"

I'm using an IFD440 and it only has one ARINC 429 out.


Edited by PA23 - 14 Oct 2022 at 3:56pm
Back to Top
rolfe_tessem View Drop Down
Senior Member
Senior Member
Avatar

Joined: 06 Jan 2012
Location: Massachusetts
Status: Offline
Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2022 at 4:07pm
Originally posted by PA23 PA23 wrote:

I'm using an S-Tec 60-2, which means I have an external GPSS steering converter, the S-Tec 55 I believe incorporated it internally.

If I am correct the GPSS steering module can accept either serial or ARINC 429 for steering information, mine is using ARINC 429, the setting for me is on the "Main ARINC 429 Config" page, I have "Out 1" speed is set to "Low" and Data is set to "GAMA 429"

I'm using an IFD440 and it only has one ARINC 429 out.


Thank you! This is very helpful as a place to start looking! I'm hoping it is something so simple as wrong protocol or wrong speed.

Rolfe
Back to Top
Victor View Drop Down
Groupie
Groupie


Joined: 03 Feb 2012
Location: Australia
Status: Offline
Points: 61 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Victor Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2022 at 7:17pm
Originally posted by rolfe_tessem rolfe_tessem wrote:

I just had my avionics shop install a Shadin ADC-200 (yellow tag) to enable air data on my IFD-540. The HSI is a King KCS-55A. I thought everything was working on the test flight -- the air data definitely works -- but now I'm getting GPSS "fail" on my STEC 55X when I try to enable GPS steering.

Before I just toss it back in the avionics shop's lap, where should they be looking for the culprit -- at the HSI end of things or at the IFD end? The STEC works fine in other modes, HDG, ALT, etc.

I'm hoping this is just some parameter or speed mis-match but maybe someone here has some experience with something similar. I've opened a ticket with Avidyne but haven't been able to get back to the airport to download logs yet. I've emailed STEC support, with no response.

Thanks for any pointers!

Rolfe


I used to have a similar setup and experienced those same issues, which baffled both me and my installer. Each time this happened I would recycle the 55X and the GPSS would work fine.

I also discovered that on the ground following powering up the Avionics Master switch, I had to allow the IFDs to fully initialise first before the 55X was switched on and initialised resulting in no further GPSS failure.

My installer could determine why this solution worked and it may not be the solution to your issue, but it is a simple, cost free method to try.


Edited by Victor - 14 Oct 2022 at 7:18pm
Back to Top
rolfe_tessem View Drop Down
Senior Member
Senior Member
Avatar

Joined: 06 Jan 2012
Location: Massachusetts
Status: Offline
Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2022 at 8:35am
Originally posted by Victor Victor wrote:

Originally posted by rolfe_tessem rolfe_tessem wrote:

I just had my avionics shop install a Shadin ADC-200 (yellow tag) to enable air data on my IFD-540. The HSI is a King KCS-55A. I thought everything was working on the test flight -- the air data definitely works -- but now I'm getting GPSS "fail" on my STEC 55X when I try to enable GPS steering.

Before I just toss it back in the avionics shop's lap, where should they be looking for the culprit -- at the HSI end of things or at the IFD end? The STEC works fine in other modes, HDG, ALT, etc.

I'm hoping this is just some parameter or speed mis-match but maybe someone here has some experience with something similar. I've opened a ticket with Avidyne but haven't been able to get back to the airport to download logs yet. I've emailed STEC support, with no response.

Thanks for any pointers!

Rolfe


I used to have a similar setup and experienced those same issues, which baffled both me and my installer. Each time this happened I would recycle the 55X and the GPSS would work fine.

I also discovered that on the ground following powering up the Avionics Master switch, I had to allow the IFDs to fully initialise first before the 55X was switched on and initialised resulting in no further GPSS failure.

My installer could determine why this solution worked and it may not be the solution to your issue, but it is a simple, cost free method to try.

Victor,

Thanks for this -- yes, it is a simple thing to try and I believe I've heard of someone else having a similar power-up sequence issue.

Rolfe
Back to Top
oskrypuch View Drop Down
Senior Member
Senior Member


Joined: 09 Nov 2012
Location: CYFD
Status: Offline
Points: 3060 		Post Options Post Options   Thanks (0) Thanks(0)   Quote oskrypuch Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2022 at 2:47pm
Quote
I also discovered that on the ground following powering up the Avionics Master switch, I had to allow the IFDs to fully initialise first before the 55X was switched on and initialised resulting in no further GPSS failure.

That is precisely the solution.

If you let the STEC 55x boot up first, it will set and lock a speed for the RS232 line, and will not adjust again. If that doesn't match the transmitted speed that the IFD is using for that Rs232 out, then you will get GPS FAIL on the STEC.

However, if the IFD is already running and transmitting, the STEC will sync correctly.

So, just remember to TURN OFF the A/P before shutdown (not a bad idea anyway), and then do not power it up until the IFD has booted already.

* Orest



Edited by oskrypuch - 15 Oct 2022 at 6:25pm
Back to Top
PA23 View Drop Down
Senior Member
Senior Member


Joined: 12 Oct 2019
Location: MMU
Status: Offline
Points: 304 		Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2022 at 2:50pm
I'm guessing I don't have that issue with mine either because I'm using a 60-2 with the GPSS module, and/or because it gets steering information via ARINC and not RS-232.

To you statement, I wonder what speed the S-TEC 55X is expecting when it defaults to a given speed, maybe set the output of the IFD to be that speed?
Back to Top
oskrypuch View Drop Down
Senior Member
Senior Member


Joined: 09 Nov 2012
Location: CYFD
Status: Offline
Points: 3060 		Post Options Post Options   Thanks (0) Thanks(0)   Quote oskrypuch Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2022 at 6:21pm
Our issue was that if we matched the 55x default RS232 speed, it would be affect another part of our setup unfavorably.

If has been a while, but I think it related to the inability (early on in the IFD firmwares) to have different speeds on in/out of the IFD port, or we needed HI speed for something else, something like that. That may no longer be a limiting (install) issue.

* Orest



Edited by oskrypuch - 15 Oct 2022 at 6:24pm
Back to Top
rolfe_tessem View Drop Down
Senior Member
Senior Member
Avatar

Joined: 06 Jan 2012
Location: Massachusetts
Status: Offline
Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2022 at 8:55am
Originally posted by oskrypuch oskrypuch wrote:

Quote
I also discovered that on the ground following powering up the Avionics Master switch, I had to allow the IFDs to fully initialise first before the 55X was switched on and initialised resulting in no further GPSS failure.

That is precisely the solution.

If you let the STEC 55x boot up first, it will set and lock a speed for the RS232 line, and will not adjust again. If that doesn't match the transmitted speed that the IFD is using for that Rs232 out, then you will get GPS FAIL on the STEC.

However, if the IFD is already running and transmitting, the STEC will sync correctly.

So, just remember to TURN OFF the A/P before shutdown (not a bad idea anyway), and then do not power it up until the IFD has booted already.

* Orest

Orest,

Thanks for this! I'll be checking it out tomorrow!

Regards,

Rolfe
Back to Top
PA23 View Drop Down
Senior Member
Senior Member


Joined: 12 Oct 2019
Location: MMU
Status: Offline
Points: 304 		Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2022 at 1:11pm
I know Avidyne had issues early on with different speeds in vs out on the same channel, but I believe that has been fixed long ago.

If I had to guess the S-Tec is probably expecting 9600 bps for the speed.
Back to Top
oskrypuch View Drop Down
Senior Member
Senior Member


Joined: 09 Nov 2012
Location: CYFD
Status: Offline
Points: 3060 		Post Options Post Options   Thanks (0) Thanks(0)   Quote oskrypuch Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2022 at 1:44pm
My install was a long time ago too!

Now that I think about it, I believe that it was like this ... we wanted to reserve HI speed for ASPEN / IFD comm. When the STEC boots up, if it finds HI speed transmissions it will keep the HI speed, else if all is quiet, it will downstep to LO and stay there. It never checks again, unless it is power cycled of course.

There was (is?) no way to change this STEC behavior or set a default speed (unlike the IFD or ASPEN).

So booting up IFD first, then STEC 55x, allows for them to handshake. It is just automatic now for me, and there is perhaps some value to having the A/P OFF on initial startup, so I have never bothered to explore any further solutions.

But, it is a real gotchu, if you don't know what is going on.

* Orest


Edited by oskrypuch - 17 Oct 2022 at 1:47pm
Back to Top
rolfe_tessem View Drop Down
Senior Member
Senior Member
Avatar

Joined: 06 Jan 2012
Location: Massachusetts
Status: Offline
Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 2022 at 10:05am
Since I started this thread, I thought it would be appropriate to end it with the solution.

It turns out that recent avionics work (air data computer connection from HSI to IFD) required removing IFD and the STEC 55X which sits above it. The STEC55X computer is a very tight fit in the tray, and the shop did not completely reseat it. But, complicating matters, they reseated it just enough to work on the flight home where everything was flawless. It was the next flight when it failed GPSS and the next flight after that wouldn't power up at all. That was the clue that led us to take both units out and reseat both. The bezel on the 55X sits further recessed from the lip of the IFD. If they are even, the autopilot appears seated correctly, but isn't. There is a second push of about 1/4 inch to go.

Hopefully, this saves someone else some time when troubleshooting a similar issue!

Rolfe
Back to Top
oskrypuch View Drop Down
Senior Member
Senior Member


Joined: 09 Nov 2012
Location: CYFD
Status: Offline
Points: 3060 		Post Options Post Options   Thanks (0) Thanks(0)   Quote oskrypuch Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 2022 at 11:19am
What a satisfying fix. The best ones are simple ones.

* Orest
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.074 seconds.