Connecting PAW to a Becker BXP6401 Transponder for ADS-B Out

[Moffrestorer]

Hi Guys,

Does anyone have any experience of connecting this type of Transponder to PAW? I finally bit the bullet and had our mode S Transponder modified at the factory to latest hardware and software spec including setting of SIL and SDA = 0. I reinstalled it into the aircraft and wired it to the PAW using the FTDI USB - RS232 converter cable (orange wire to Plug 9 pin8, and black wire to Plug 9 pin9). I also grounded Plug 9 pin2 (GPS Enable) as specified in the installation diagram.

When I switched the Transponder and PAW on, the Transponder performs a self test and this indicated FAILURE. If I disconnected the ground to P9/2, the Transponder recovered and the failure mode disappeared. I confess that The aircraft was in the hangar but I did have good GPS fix of 7 satellites as shown on PAW home screen and was able to view CAT traffic on Easy VFR on the tablet.

I didn’t see any LED indication at all on the FTDI converter of data transmission and did try configuring port 3 of the PAW into which I’d plugged the converter, to 4800 baud.

Thinking about the Transponder self-test several days later, I think that possibly the failure indication might disappear once the GPS source requirement is seen to be compliant/ stable and I might need to wait longer for this to occur, so will try this when I can get across to the airfield again.

Lee,

I noticed that the config page port configuration has a number of drop down options such as GPS, Trig, Funke etc. Can you say what the difference is between say Trig and Funke, if selected and what might be the best setting to use for the Becker Transponder. The manual says it will interface with serial asynchronous transmission parameters: 4800, n, 8, 1 and transmit data with NMEA-0183 protocol GGA and VTG sentences.

Thx,

Chris

[Ian Melville]

I would be looking to see why the FTDI has no LED flashing first.

Have you got the correct adaptors? Very easy to buy the FTDI USB-TTL version
Have you configured the correct port. I always check with the FULL manual, rather than the quick Start Guide, which differs. 🤔 I also notice that the Becker manual is using RX+ and RX- on the transponder and TX+ and TX- on the GPS, that leads me to think that the Becker diagram is misleadingly annotated.

I think RX+ is data-in RX- is TX-out. And that you should connect the Orange to Plug 9 pin 8(RX+) and if you want, the Yellow to Plug 9 pin 9(RX-). The black should go to ground Plug 9 pin 13. It would also appear that you need to connect Plug 8 or 9 pin 2 (depends on you altitude encoder. See section 2.5.13) to ground to tell the Becker it has a GPS.
If that does not work swap the wires on pins 8 and 9.

Quickest way for you to test, would be to move the From pin 9 to pin 13 as you seem to have done everything else. Speed 4800, and try both GPS types. If no joy move the orange to PIN 9.

Hope this helps?

[Admin]

Hi  Chris

I agree with Ian, biggest culprit TTL vs RS232

I will check on messages, but GPS should be sufficient

Thx lee

[exfirepro]

Chris,

Figure 11 on Page 42 of the Becker Installation & Operation Manual clearly shows that as you are using an RS232 GPS source, the 'Orange' (Tx Data) wire from the FTDI cable should go to Pin 9 on Becker P9 and the 'Black' (Ground) wire from the FTDI should go to Pin 8 on Becker P9 (which should also be connected to Pin 13 and Ground). Becker Pin 2 should also be connected to 'Ground' to 'enable' the GPS function.

The Becker Manual also states that....

The equipment is capable to operate with following certified GPS receivers:
• FreeFlight System GPS/WAAS 1201 Sensor, part number 84100-02-XXXX
• NexNav miniGNSS/ GPS-SBAS Sensor/ Receiver.

The equipment is capable to operate with following Garmin® products:
• Garmin® GNS 430
• Garmin® GNS 430W
• Garmin® GNS 530
• Garmin® GNS 530W

The equipment is also capable to operate with GPS receivers which providing EIA-232C or EIA-422 interface with serial asynchronous transmission parameters: 4800, n, 8, 1 and transmit data with NMEA-0183 protocol GGA and VTG sentences.

I'm pretty sure GPGGA sentences are provided via the 'Transponder Trig' USB port setting. Lee would be able to confirm this.

As Ian has said, you need to make sure you are using a 'Serial Level' USB to RS232 cable and that you have enabled the 'correct' USB port on your PAW. If in doubt look at the photos in the document I wrote on connecting FlarmMouse to PilotAware - available on the main PilotAware website www.pilotaware.com

Regards

Peter

[Ian Melville]

Just done a bit of digging. Not easy to find stuff on RS232-RS423 mix. Peter is right that the orange should go to RX-, RX+ should be grounded. RS 423 standard is a twisted pair each way, hence the RX+ and RX- for incoming data.

[Moffrestorer]

Thanks for your very valuable input, Ian, Lee and Peter.

Reviewing what I did the other day I found that I configured the wrong PAW port (USB 3 vice 2) as I was working from memory, which at my age clearly isn’t too good! Also, forgot to SAVE the setting, which is probably a blessing in disguise as I’ve left the Transponder in non-ADS-B mode and the PAW should work normally until I can get back to the airfield to sort things out correctly.

I purchased the FTDI cable from Farnell, but as I couldn’t find the link to the recommended type, ordered one making sure that it was not the TTL version. The one I have is USB-RS232-WE-1800-BT_5.0  As far as I can tell, the 5.0 suffix purely means it supplies 5v dc on the red conductor and as I’m not using that the cable should be OK for this application.

The cable connection to the Transponder Plug 9 pins are fairly confusing from the diagrams in the manual and depend on which altitude encoder is used. I have the Becker BE6400 encoder which plugs into J 8.

 

Figure 11 on Page 42 of the Becker Installation & Operation Manual clearly shows that as you are using an RS232 GPS source, the 'Orange' (Tx Data) wire from the FTDI cable should go to Pin 9 on Becker P9 and the 'Black' (Ground) wire from the FTDI should go to Pin 8 on Becker P9 (which should also be connected to Pin 13 and Ground). Becker Pin 2 should also be connected to 'Ground' to 'enable' the GPS function.

The diagram posted on the gliderpilotshop.com web-site agrees with this, but Figure 11 of the Becker O&M Manual is annotated “not with BE6400”.

I think the best thing I can do is see whether the current layout works when the correct port is configured and SAVED. If no activity seen on converter Red LED try reversing cable connections to P9, and if still no good wire per Figure 11. Hopefully unlikely to blow anything up!

Thx,

Chris

[Moffrestorer]

Well it’s now working fine as shown on the traffic page of my spare PAW.

Once I’d configured the correct USB port that the FDTI cable is plugged into the red transmit LED in the converter started flashing approx once per second. With ADS-B Enable (P9-2) grounded the transponder still indicated “Failure”. This was sorted by reversing the cable connections as suggested by Peter and Ian, so Orange wire to P9-9, black to P9-8. Grounded P9-13, P9-25.

I got “failure” with the port configuration selected to “Trig” but  it was OK with it configured to “Funke”.

Thanks for all your help.

Chris

[exfirepro]

Well done Chris,

Glad that between us we got to the bottom of it and you now have everything working. It sets a great precedent and reference point for anyone wanting to go ADSB Out using a Becker BXP6401 in the future. Presumably also good background information for any other Becker transponder users as the principles should be much the same.

Best Regards as always

Peter