ARINC-429 Offline

[cbretana]

I have been trying to diagnose and fix this for two months now. Any information or suggestions would be appreciated.

I have a Garmin GPS175, hooked up to my Skyview HDX using the ARINC-429. Initially, it worked fine, and I had no issues.

Then, it suddenly started acting up, intermitentently, without any obvious pattern. Most of the time when the HDX was initially powered up, it would be okay, but after a period of time operating normally, it would drop offline, with a WARNING notification, and a ARINC-429 OFFLINE message. The first time this happened it was 20-30 minutes into the flight, after operating normally up to the failure.

Subsequent failures have occurred after different lengths of normal operation, but in almost every case the system works for some length of time before failing. (Sometimes, less frequently, it fails with the offline message immediately after applying power. Also less frequently, I get a CAUTION, with a failure notification GPS1 FAIL message. (I named the GPS175 "GPS1" in the configuration setup). Occasionally, I also get an SV-KNOB-PANEL OFFLINE failure, even though the knob panel is on a completely different network cable.

[Added]
In all these failures, the GPS175 continues to operate normally.. As far as Ican tell, it is unaffected by the failure of the ARINC-429 to communicate with the Skyview over the network.

I have replaced the ARINC-429 module with a brand new one, but I am still experiencing the same symptoms. I have also checked the pinouts on all the network cables, (including the cable between the GPS175 and the ARINC-429), with a circuit tester. A Dynon tech suggested that leaking EM from the Transponder antenna or coax might be interfering with the 429 module, so I relocated it further from those things and wrapped it in aluminum tape (trying to create a makeshift Faraday box).

I have also replaced the network cables between the ARINC-429, and the Knob panel, (as well as other components) with new manufactured RS232 DB-9 cables. So far nothing works. Do these 9-wire Skyview Network cables need to be shielded? Is so, are manufactured RS232 DB-9 cables shielded?

Is it possible that something in the main HDX computer screen might be causing these symptoms? If that is possible, I do have a second 10 inch HDX screen I could test in this plane.

Another possibility is the configuration setup parameters. Since the system worked for some time before it started to show symptoms, and now, (intermittently) works when power is first applied, I assume that the setup config parameters are correct and have not changed.. But could a bad/incorrect setup parameter cause these symptoms?

If anyone else has experienced these or similar symptoms, your experience could be helpful.

Thanks in advance

 

[RV8JD]

I'm not sure this will help, but check this thread on VAF and the posts regarding tray alignment starting at Post #11:

Gps 175 needs service message

Hey all, New dynon hdx along with a GPS 175. I'm getting a " service gps message" . Tried re rack, Pins aren't bent, harness was made from spruce. Config module is in. Picks up like 10 satellites inside of a CBS hangar with the door shut. What do you all think

www.vansairforce.net

 

[cbretana]

RV8JD,

In all the failures I experienced, the GPS175 continues to operate normally.. As far as Ican tell, it is unaffected by the failure of the ARINC-429 to communicate with the Skyview over the network. So I don't think the issue is related to the connection to the GPS antenna.

But I will check it out...

 

[airguy]

You've replaced the ARINC itself, and the data cables in/out - what about the power and ground? Verify those are good, including any breaker/switch the power is coming from.

 

[cbretana]

Power and ground are fine, The GPS 175 unit continues to function normally, and the Power and ground wires for the ARINC-429 are on two of the DB-9 pins.

 

[maartenversteeg]

You are referring to the cables as "RS232 DB-9 cables", but note that the Dynon network cables are NOT standard RS232 cables. The specification for the Dynon databus cables are found in the installation manual and involve specific signals and return lines from the DB-9 connector to be twisted. Straight through RS232 cables might work but may be much more sensitive to EMI and hence produce occasional problems. I assume that you used the Dynon specification for the DB-9 cables and you are just naming the cables incorrectly, otherwise this might be something to investigate.

 

[Rhino]

Standard cables will not work, twisted or not. The Skyview network uses different pinouts from a standard RS-232. You could cause serious damage with a standard RS-232 cable.

 

[OldBoldPilot]

If the Skyview network vs RS-232 cables aren't the source, the only other thing I can think of is a weak connection or cracked circuit board--it connects when everything is cool, but as the module(s) heat up and things expand, the connection breaks and the output signal is lost. This might explain why things work at startup but fail after some amount of time of operation. The variation in times might be related to different ambient temperatures--maybe it's longer on cool days and shorter on hot days? Since you've replaced everything else, it'd have to be in the GPS itself. If so, since the GPS seems to continue working (internally), the failure would seem to be in the output circuitry of the GPS.

 

[Rhino]

Vibration can also play into that. The really fun problems are those caused by heat and/or vibration, because they're usually the hardest to diagnose.

 

[n28et]

I have been trying to diagnose and fix this for two months now. Any information or suggestions would be appreciated.

I have a Garmin GPS175, hooked up to my Skyview HDX using the ARINC-429. Initially, it worked fine, and I had no issues.

Then, it suddenly started acting up, intermitentently, without any obvious pattern. Most of the time when the HDX was initially powered up, it would be okay, but after a period of time operating normally, it would drop offline, with a WARNING notification, and a ARINC-429 OFFLINE message. The first time this happened it was 20-30 minutes into the flight, after operating normally up to the failure.

Subsequent failures have occurred after different lengths of normal operation, but in almost every case the system works for some length of time before failing. (Sometimes, less frequently, it fails with the offline message immediately after applying power. Also less frequently, I get a CAUTION, with a failure notification GPS1 FAIL message. (I named the GPS175 "GPS1" in the configuration setup). Occasionally, I also get an SV-KNOB-PANEL OFFLINE failure, even though the knob panel is on a completely different network cable.

[Added]
In all these failures, the GPS175 continues to operate normally.. As far as Ican tell, it is unaffected by the failure of the ARINC-429 to communicate with the Skyview over the network.

I have replaced the ARINC-429 module with a brand new one, but I am still experiencing the same symptoms. I have also checked the pinouts on all the network cables, (including the cable between the GPS175 and the ARINC-429), with a circuit tester. A Dynon tech suggested that leaking EM from the Transponder antenna or coax might be interfering with the 429 module, so I relocated it further from those things and wrapped it in aluminum tape (trying to create a makeshift Faraday box).

I have also replaced the network cables between the ARINC-429, and the Knob panel, (as well as other components) with new manufactured RS232 DB-9 cables. So far nothing works. Do these 9-wire Skyview Network cables need to be shielded? Is so, are manufactured RS232 DB-9 cables shielded?

Is it possible that something in the main HDX computer screen might be causing these symptoms? If that is possible, I do have a second 10 inch HDX screen I could test in this plane.

Another possibility is the configuration setup parameters. Since the system worked for some time before it started to show symptoms, and now, (intermittently) works when power is first applied, I assume that the setup config parameters are correct and have not changed.. But could a bad/incorrect setup parameter cause these symptoms?

If anyone else has experienced these or similar symptoms, your experience could be helpful.

Thanks in advance

I too have been experiencing the GPS1 Fail message. No rhyme nor reason. Sometimes, it happens within a few minutes of operation and other times well into the flight. Very frustrating to say the least. However, no message regarding the ARINC-429 being off line.

I also have the GPS175 connected via a GAD29 (Garmin ARINC-429 module) to a G5, and both Garmin units continue to work just fine.

Sorry, I don’t have a solution to offer any this time.

 

[airguy]

Same here with the GPS 1 message, no clue as to how/why/who/when/where

 

[madison519MM]

I have seen this same behavior in my system while running on the bench. (Building new plane, have entire Dynon system with ARINC to GNX-375 connected and running.) It seems like the ARINC module may be susceptible to short power transients/undervoltages, and it drops off-line. All the other Dynon modules and the GNX-375 continue to run normally when this happens. The Dynon backup battery does not prevent it from happening. I have not been able to troubleshoot it exhaustively, because after it happens once, you can repeat the same scenario and then it keeps working. I’m out of town this week, but hearing that other people are having the same problem makes me more concerned so I’ll try to debug it further. I had talked to Dynon about it, but was unable to reliably replicate the problem so that didn’t go very far.

 

[cbretana]

Standard cables will not work, twisted or not. The Skyview network uses different pinouts from a standard RS-232. You could cause serious damage with a standard RS-232 cable.

I used a circuit tester on both and except for possible twists in the wiring of the individual wires inside the cable, they are identical. Pin 1 on one end terminates in pin 1 on the other end, pin2 goes to pin2, etc., etc. You may be thinking if a null modem cable where the data in and data out pins are swapped.

 

[bbaggerman]

Standard cables will not work, twisted or not. The Skyview network uses different pinouts from a standard RS-232. You could cause serious damage with a standard RS-232 cable.

Not sure what a "standard" RS-232 cable is but as @maartenversteeg and @cbretana note as long as Pin 1 goes to Pin 1, etc. on down the line then the cable shouldn't hurt anything. The data rate is 1 megabits per second so having the appropriate pair twisted starts to become important for EMI and noise immunity, but for a short run it will probably appear to work just fine. It wouldn't be correct for installation because the data pairs need to be twisted for the cable to meet the SkyView spec but I'd be comfortable sticking in a commercial cable as an extension or just for ground test and see what happens.

 

[Rhino]

I mispoke. You may get standard cables to work with ARINC, but they should be twisted. Dynon serial network connectors do not use standard RS-232 pinout functions. Hooking them to a non-Dynon device, or using a standard RS-232 cable on a serial device, will not work, and could cause damage. That’s what I was thinking of when answering above.