Help requested - Serial Ports not found

[bscycleman]

I'm not having any luck installing the transponder or ADSB-in boxes. Both boxes are listed as "Not Found" by the HDX after they are configured in the serial connection menus. I've verified theyare connected correctly, at least 10 times. I even bypassed the signal wires to rule out a break in the lines even though they have continuity from end to end.

I contacted Dynon tech support when I thought it was isolated to the transponder. They requested I send it back to them. While the transponder was making it's round trip, I ran into the same problem with the 472. I realize the common denominator is the installer and have run out of ideas to troubleshoot the issue. Here's what I've done so far:

- Confirmed 12 volts on the positive leads (direct from main bus)
- Confirmed good grounds running back to common ground on firewall
- Confirmed pins assignments are correct
- Swapped Rx and Tx wires
- Confirmed continuity of signal wires from connector to connector
- Switched transponder from port 1 to port 4

For both boxes the HDX lists them as "not found" and the tx count climbs while the rx count stays at zero. The GPS-2020 is connected and works as expected. I also connected the tx wire for port 3 to the ELT and confirmed it's getting a good location signal.

I got the transponder back on Friday but they did not find anything wrong with it. I'll call tech support again on Tuesday, but am hoping someone here might have a solution or other ideas.

Brian

 

[swatson999]

What is the red LED on the ADS-B box doing?

Do you have the ACM? I see there are specific port requirements if you do...

 

[bscycleman]

Steve,

The LED is solid green. I looked through the install manual, solid is not good. I don't know if this is a holdover for the 470 since they mention a red LED.

What is the ACM?

 

[swatson999]

Steve,

The LED is solid green.  I looked through the install manual, solid is not good.  I don't know if this is a holdover for the 470 since they mention a red LED. 

What is the ACM?

I don't know about green, but the manual says that on solid means it's broken to contact Dynon. Check the installation manual.

ACM is the AFS Advanced Control Module.

Did you read the installation manual thoroughly?

 

[Raymo]

Confirm your RS232 wires are TX > RX and RX > TX on the same COM port.

 

[Dynon]

Probably best to continue this directly with our support staff, since you're already working with them. First, a comment - if we've had the transponder back and it work here - this is almost definitely a wiring issue. A couple of things to check: If you have multiple displays, are both displays getting both of the serial port wires? Is the serial port set up correctly? Have you looked in the serial port setup and checked the TX and RX counters to discern if the display(s) are seeing any data at all? Another thing to check is pin-to-pin continuity on your harnesses.

 

[bscycleman]

Just to follow up.  Tech support spent over an hour on the phone with me this evening while we worked out what we believe to be the problem.  This is excellent support in my book.

A note of caution. I did all of the below steps with guidance from tech support. I would not have jumped any of the wires as I would have expected to smoke something in the process. Follow my explanation at your own risk.

Full disclosure: During the process I found a problem I created while doing my own diagnostics over the weekend.  While removing the RX/TX pins on the transponder harness I put them back in the wrong place.  This prevented me from getting a good comparison of ports 1 and 4.  I mistakenly thought the transponder did not work on port 4 either.

Now for the current thought:  Ports 1 and 2 are not working, 3 and 4 are good-to-go.  Garrett had me jumper the TX/RX pins at the transponder (port 1) and the ADSB (port 2).  This should have shown RX, TX, and good sentences counting up.  Unfortunately it did not work.  We then jumped port 4 and it showed RX, TX, and good sentences counting up as they should.  With port 4 confirmed good, we moved the transponder to this port.  I did this by moving the pins in the 37 pin connector on the back of the EFIS.  I then plugged in the transponder (this is when I noticed my pin error).  Viola, it worked!  The transponder is on-line with all functionality expected.

We then went through jumping each port on the 37 pin connector.  This is how we confirmed ports 1 and 2 are not working while 3 and 4 are good. 

Garrett asked for the HDX back in the shop for confirmation and repair.  I'll close the loop with what I hear back from Dynon.

Brian

 

[bscycleman]

To wrap up this thread and put a bow on it, The HDX did have two bad serial ports. Dynon came through and fixed the EFIS and returned it to me in about 10 days. It was like Christmas all over again when the HDX arrived. I dropped it in the pannel, connected the wires and powered it up. Everything worked as it should and the transponder and 472 came on line.

Brian

 

[Bret]

I had a similar problem when I added a second HDX, transponder and ADSB not found on HDX after assigning serial ports and transponder set up, after hours of trying to set up, I uninstalled both on the serial ports and THEN re configured, transponder was on serial port one, installed on 2, ADSB was on serial port 2, installed onto serial port 1, I don't know why, but by switching the serial ports, they both were found and started working.