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AERA660 RS232 Output Test?

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farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Wed Sep 03, 2025 2:10 pm Post subject: AERA660 RS232 Output Test?

Is there a way to test if one of the Aera660 RS232 output lines is producing an output?  For example, using a multimeter on the output pin in the connector?  I'm trying to send NEMA data to an engine monitor and ACK ELT.  Previously it was working but now the engine monitor is not receiving GPS data and the ELT gps reception test does not indicate data in (led connected to test lead).  Also, would testing continuity from the Aera d-sup to the monitor or ELT connection be worthwhile?  The other 232 output on the Aera is working properly connected to a GPS175.  John

werner schneider

Joined: 24 May 2021
Posts: 61

Posted: Wed Sep 03, 2025 2:48 pm Post subject: AERA660 RS232 Output Test?

search for RS-232 tester, they are cheap:



https://www.artekit.eu/products/accessories/comm/ak-rs232-tester/



On 9/4/2025 12:10 AM, farmrjohn wrote:

 	  Quote: 	
		   



 Is there a way to test if one of the Aera660 RS232 output lines is producing an output?  For example, using a multimeter on the output pin in the connector?  I'm trying to send NEMA data to an engine monitor and ACK ELT.  Previously it was working but now the engine monitor is not receiving GPS data and the ELT gps reception test does not indicate data in (led connected to test lead).  Also, would testing continuity from the Aera d-sup to the monitor or ELT connection be worthwhile?  The other 232 output on the Aera is working properly connected to a GPS175.  John





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=515594#515594

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Thu Sep 04, 2025 4:45 am Post subject: Re: AERA660 RS232 Output Test?

John,  

if you have a PC and a “usb to serial” adapter, along with a freeware utility like “Termite,” you can monitor the serial port output. A low cost SERIAL TO USB adapter can be purchased from numerous sources, including Amazon.  I’ve had good luck with the “StarTech” products but I trust Adafruit to supply a good converter at a reasonable price.



https://www.adafruit.com/product/18?srsltid=AfmBOoo_bZLXZv_gCpq8NnZGhvPIanZlLrROhgZU7QATwnqcJCStl4YE74c



The challenge is (sometimes) the serial cabling, as the rs232 “standard” has been very casually followed for many years (wrt the pin conventions on the db9 connector).



https://termite.software.informer.com/3.4/



The terminal software (Termite) can display the data stream from the source aero660.



If you go this path I would first monitor a known working channel on the aero660 to insure wiring and rs232 settings are correct (baud rate, stop bits, etc.).



Dan T.

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Thu Sep 04, 2025 5:37 am Post subject: Re: AERA660 RS232 Output Test?

John,



After a quick check of the connections you have on the aero660 housing, I think you might be better off with a serial to USB breakout connector.



https://www.adafruit.com/product/5995?srsltid=AfmBOop_JYaz2XhB0LqsZ5naUVbA8YjZaZFhtZdp9xzlpo6gJzH30jIge8s



Assuming you can get access to the tx and rx wires from the aero660, you can connect them to the complimentary terminals on the breakout (e.g. tx to rx and rx to tx).



Then USB to the PC and with Termite, you can monitor the data stream.



Dan T.

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Thu Sep 04, 2025 10:29 am Post subject: Re: AERA660 RS232 Output Test?

I'm not sure how those connectors would work.  In my case the bare wire cable from the Aera goes to a 9 pin d-sub, pinned as follows: 



1-Black (gnd)

2-Red (power)

3-Green (audio common)

4-White (audio R)

5-Brown (Audio L)

6-Purple (232-2 rx)

7-Orange (232-2 tx)

8-Yellow (232-1 rx)

9-Blue (232-1 tx)



It is pin 7 (232-2 tx) that I'm interested in.  It does not appear to be sending to either the engine monitor or elt.  Pins 8 and 9 are working correctly with the GPS175.  It would not be a problem to make a pigtail to connect to pin 7.  Pin 6 (232-2 rx) is not connected to anything beyond the d-sub.  



If I connected the d-sub to one of those testers/connectors what impact would the non 232 pins have?  Is it possible to see if there is any output from pin 7 using a pigtail and multimeter?



John

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Thu Sep 04, 2025 11:08 am Post subject: Re: AERA660 RS232 Output Test?

Hi John,



The breakout converter would be best used by segregating the pin of interest (pin 7) and excluding any of the other pins from being connected to the PC (via the converter). You will also need to include a communication reference (the power/data common pin) which is the black wire.  It’s not uncommon for a NEMA signal to exclude the rx pin as they often do not require any command signal to transmit GPS data but simply transfer data in the blind.



A multimeter might “wiggle” a bit but the signal oscillating speed is much to high to be of much use.  It might show some average voltage values, depending on the character strings being sent.



An oscilloscope would be required to capture the voltage signal.  the terminal emulation software (termite) reads the oscillations and interperets the ASCII to text so you can read it.



Dan T.

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Thu Sep 04, 2025 6:03 pm Post subject: Re: AERA660 RS232 Output Test?

Dan- A couple of questions on how to use the breakout converter.  1. Would I connect pin 7 (RS232) to the RS232 TX terminal and pin 1 (gnd) to the RS232 GND terminal?  2. Would a USB port on the panel work to power the converter vs. a computer?



It might be simpler to switch pins 7-9 on the output side of the d-sub and re-set the 232 settings appropriately for the Aera to check.  Or, would a continuity test for the output side from terminal 7 be appropriate?



John

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Fri Sep 05, 2025 5:30 am Post subject: Re: AERA660 RS232 Output Test?

Hi John,



   1. Would I connect pin 7 (RS232) to the RS232 TX terminal and pin 1 (gnd) to the RS232 GND terminal?



Pin 7 (TX) will be connected to the RX terminal on the breakout. The connections on RS232 are typically connected in a “complimentary” nature. Transmit (TX) on the source device will connect to Receive (RX) on the receiving device.



    2. Would a USB port on the panel work to power the converter vs. a computer?



NO. Do NOT include the panel USB power. 

The PC’s USB port will power the converter. Only the power common (which is also used as the signal common) is used / needed..



 2a.  It might be simpler to switch pins 7-9 on the output side of the d-sub and re-set the 232 settings appropriately for the Aera to check.



YES! 

Switching the output signals is a good way to evaluate the problem. 

 This assumes pin 8 (rx channel 1) is not connected beyond the db9.

This test would also assume the baud rate is the same on both channel 1 and 2 in the aero.  (I’ve not looked into the configuration options for the aero to see if this is even an issue).



Dan.

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Sat Sep 06, 2025 6:35 am Post subject: Re: AERA660 RS232 Output Test?

Thanks. To clarify, I would only connect pin 7 but not pin 1 to the converter. 



The 232 outputs are different. In the present configuration all pins are connected to the Aera but pin 6 is not connected out. The format for pins 6 and 7 is NMEA and for 8 and 9 MapMX. If I switched the wiring on the d-sub out then pins 6 and 7 would be connected and the output changed to MapMX. 



Does the make of computer matter, I.e. PC or Mac?

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Sat Sep 06, 2025 9:18 am Post subject: Re: AERA660 RS232 Output Test?

Hi John,



For wiring to the serial to USB breakout, you need the gnd wire (pin 1 from the Aero) in addition to the TX (pin 7 from the Aero).  So, 2 wires need to be connected from the Aero to the USB to serial breakout.  Sorry for the confusion....



I've not used any of the terminal emulators with a MAC OS.  I've always used a PC.  



I have a Mac Mini and note that there is a "built in" terminal program that is NOT used (as far as I can tell) to communicate out a serial port.  I believe it is designed as text command interface with the Mac OS.  I'm not sure you can configure the terminal.app in a Mac for serial analysis.



I like your idea of simply re-directing the configuration of the Aero and swaping the pin connections for the map data and the NEMA output.  This is a good first step (if it is easy enough for you to re-route the pins).



A lot simpler than buying hardware and loading software you are not familiar with.



In my mind there are three most likely causes for the loss of GPS position output:



1) broken / loose wire

2) failed output port on the Aero

3) modified configuration of the Aero (not sure how this could happen)

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Sun Sep 07, 2025 1:39 pm Post subject: Re: AERA660 RS232 Output Test?

Dan-



Agree with 1 and 2 as the possible causes, which is what prompted my initial question.  I would be very surprised if it was 3 since the only change was switching the mode for pins 8 and 9 from NEMA to MapMX before the issue became apparent.  I'll try the pin swap on the d-sub output side first.



John

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Mon Sep 08, 2025 2:44 pm Post subject: Re: AERA660 RS232 Output Test?

I swapped the pins on the output side of the d-sub.  Pins 6 and 7 set to MapMx work properly.  Pin 9 set to NMEA does not (the same as when it was on pin 7).  The wire continuity for the output side for the NMEA pins appears good.  Another option would be to utilize an unused 232 port on the GPS175 vs. the Aera's if I can't get the NMEA output from the Aera to work.  I have an inquiry in to Garmin on checking the output.  Or, I could try and find a loaner Aera660 and try that, setting the 232 outputs is simple enough.

dj_theis

Joined: 28 Aug 2017
Posts: 68
Location: Minnesota

Posted: Tue Sep 09, 2025 5:12 am Post subject: Re: AERA660 RS232 Output Test?

John,



You asked this question in the original post:



 	  Quote: 	
		   Also, would testing continuity from the Aera d-sup to the monitor or ELT connection be worthwhile?  The other 232 output on the Aera is working properly connected to a GPS175.  John 	




Yes, you can (and I would) check continuity from the Aera to the receiving devices.  This includes verifying continuity between the ground wire on the ELT, the engine monitor and the ground wire on the Aera. 



 If it’s possible to do, I would also separate the ELT from the engine monitor and test them separately (both for continuity of the tx and ground from the Aera as well as checking to see if they receive the NEMA signal without the other in the circuit). Either the ELT or the engine monitor could be the bad actor and killing the transmission from the Aera.

_________________
Dan Theis
Scratch building Sonex #1362
Revmaster Alternator problem solved.

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Tue Sep 09, 2025 8:09 am Post subject: Re: AERA660 RS232 Output Test?

I hadn't checked the grounds for the engine monitor and elt.  I had also considered disconnecting the connectors for the monitor and elt in turn to see if one could be a bad actor.  Unfortunately separating the feeds won't work due to a solder splice.



It also looks as if using the GPS175 for the gps source may not be an option.  I don't see NMEA9600 as an option for the serial ports configurations so have an inquiry into Garmin and E.I. in that regard.



John

Eric Page

Joined: 15 Feb 2017
Posts: 259

Posted: Tue Sep 09, 2025 1:04 pm Post subject: Re: AERA660 RS232 Output Test?

 	  farmrjohn wrote: 	
		  ...the engine monitor is not receiving GPS data and the ELT gps reception test does not indicate data in (led connected to test lead). [...] The other 232 output on the Aera is working properly connected to a GPS175. 	


I've been silently following this since you've been getting great troubleshooting advice, but I'm not sure I understand your setup.  A couple of questions:



1. If I understood your original post correctly, the aera 660 is providing position data to the GPS175.  If that's right, why is it set up this way when the GPS175 is an approach-certified WAAS receiver itself?  Do they cross-compare and alarm if they disagree?



2. I'm puzzled why, with the GPS175 installed, you're using a portable device to feed GPS data to permanently installed avionics.  The GPS175 has three configurable RS-232 output ports.  Are all three already in use?

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Wed Sep 10, 2025 5:42 pm Post subject: Re: AERA660 RS232 Output Test?

Problem solved.  There was a short in the wire to the elt.  I found that by checking the output side wiring to ground instead of end to end.  I separated the spliced output wires and found the short was on the elt side. Also, the LED tester for the elt works to check the RS-232 output from the Aera, flashing at each data transmission (either fast or slow).



John

farmrjohn

Joined: 31 Dec 2018
Posts: 69

Posted: Wed Sep 10, 2025 5:55 pm Post subject: Re: AERA660 RS232 Output Test?

Eric-  To answer your questions, the original set up only had the Aera660 which provided GPS data to the engine monitor/elt and to MiniGAs, using one port for the monitor/elt and the other port for the Minis.  After I installed the GPS175 I used the port from the Aera that provided GPS data to the Minis and connected it to the GPS175 and changed that port's format to Garmin's MapMX from NMEA9600.  That allows the Aera map to display a detailed route depiction on a larger screen than the GPS175.  The Aera does not provide any GPS data to the GPS175 but still has its own GPS receiver.  It passes that data out the port set to NMEA9600 and goes to the monitor (and formerly the elt).  The GPS175 is providing navigational data to the MiniGAs now instead of the Aera.  I'm currently using two of the three GPS175 ports and both Aera ports.  The Aera is basically a larger map display for the GPS175 that also shows ADSB traffic via a GDL50 Bluetooth connection.  The Aera can be used as backup flight instrument in case of electrical failure since it a the GDL50 have internal batteries and the Aera has its own GPS receiver and has the active route in its memory.  It just can't be used to shoot an actual approach.  I also have a handheld radio for communication in case of electrical failure.

Eric Page

Joined: 15 Feb 2017
Posts: 259

Posted: Thu Sep 11, 2025 5:31 am Post subject: Re: AERA660 RS232 Output Test?

Aaah, OK. That makes sense now; thanks. I'm glad you found a definite cause for the problem and got it solved!

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