jferraro17

jferraro17

Opulence, I has it...
Looking for somebody to clear this all up for me, "I'm not a smart man, Jenny". :eek:

1) Gray code vs. RS232

2) Encoder vs. 696 serial input.

3) The relationship/communication from EFIS to Transponder to 696.

I have the 696, I plan on an AFS EFIS. I would like to use the Becker Mode S transponder (and Comm) for form factor reasons, but understand the Garmin 330/SL40 should work no problem.

Basically, I'm trying to avoid conflicts, work-arounds or issues before I buy the pieces to this puzzle

Stein? Anyboby, Bueller?

Thanks-
Joe
 
You are in the interface jungle!

Hi Joe,
the answer to question 1 is that grey code is a data format where the number being represented changes by only 1 bit per count. That's to say if counting in normal binary the count is 000 = 0, 001 = 1, 010 = 2 011 = 3, BUT to change to the next count 100 = 4, notice that three bits changed the 0 to a 1 and two 1's to 0's. In grey code only 1 bit changes per change in number. This gives less noise and better tolerance to errors.

RS-232 Serial is a transmission standard. In the old days it meant a signal that changed from -12 volts to +12 volts in changing from one binary state to another (0 - 1 or vice versa). Now most RS232 serial is either 0 and 5 volts or -5 to +5 volts. Here is what the Garmin manual says in back.

Serial Data Formats
? Garmin Data Transfer?the proprietary format used to exchange data with a PC or
another Garmin GPSMAP 695/696.
? NMEA In/NMEA Out?transmits NMEA position, velocity, and navigation data.
? Aviation In?the proprietary format used for connection to a Garmin panelmounted
GPS receiver. This eliminates the need to enter the destination on both
units.
? Aviation In/NMEA & VHF Out?receives aviation data and transmits out both
NMEA data, at 9600 baud, and VHF frequency tuning information to a Garmin
Nav/Comm radio.
? TIS In?receives TIS data from a Garmin Mode S transponder or other compatible
device.
? TIS In/NMEA & VHF Out?receives TIS data and transmits out both NMEA data, at
9600 baud, and VHF frequency tuning information to a Garmin Nav/Comm radio.
? None?provides no interfacing capabilities.
Advanced NMEA Output Setup
If interfacing the GPSMAP 695/696 with another piece of equipment (such as an
autopilot), the unit needs to be set to output NMEA data. If the NMEA output mode is
set to ?Fast?, the unit will output a minimum number of NMEA sentences at 1-second
intervals. If the NMEA output is set to ?Normal?, the unit will output a greater number
NMEA sentences as 2-second intervals.

If you want to discuss this at length, send me an email and I'll try to work through it with you.
Good luck
Paul
 
Paul is exactly correct (in detail) on the grey code, but I look at it much simply - grey coade requires a BUNCH of parallel wires (one for each "bit"), and serial is a single wire, in which the bits all travel, well, in series.....;)
 
Hi Joe,

Simply here is what you need to know.

1) If you use the Becker, you'll need an encoder providing grey code to the txpdr.

2) If you use the GTX-330 then you don't need an encoder. You would hook it up as follows:

AFS -> GTX-330 RS-232 Serial Input
GPS-696 -> GTX-330 for GPS input (automatically puts the TXPDR in ALT/STBY).
GTX-330 -> AFS & GPS-696 via RS-232 for TIS traffic display.
GPS-696 -> AFS via RS-232 for GPS information.

That's it!

Cheers,
Stein
 
Stein--

Thanks, makes it pretty simple. I do have one follow up...

The altitude encoder between the EFIS and the Becker transponder makes sense, do I need anything between the transponder and the 696 in order to display traffic?

Seems like the all-Garmin panel is a lot easier :eek:

See ya at OSH--
Joe
 
jferraro16 said:
Stein--

Thanks, makes it pretty simple. I do have one follow up...

The altitude encoder between the EFIS and the Becker transponder makes sense, do I need anything between the transponder and the 696 in order to display traffic?

Seems like the all-Garmin panel is a lot easier :eek:

See ya at OSH--
Joe
Click to expand...

Hi Joe,

As far as I'm aware the small 2.25" Becker Txpdrs do no provide TIS traffic information outputs. To be fair, I don't have a lot of experience with the Mode S Becker's - Mainly the Mode C's....but, with not ability to hook the Becker to the AFS for encoded altitude you'll need an encoder, and if it doesn't have TIS, there is no hook between it and the 696. I'll try to look it up when I'm in the office tomrrow to confirm.

Cheers,
Stein
 
SteinAir said:
GPS-696 -> GTX-330 for GPS input (automatically puts the TXPDR in ALT/STBY).
Click to expand...

Stein... are you sure about this one? I could be wrong, but I don't think the Garmin transponders will accept NMEA serial input. At least not in the source code I'm looking at. :)

mcb
 
mburch said:
Stein... are you sure about this one? I could be wrong, but I don't think the Garmin transponders will accept NMEA serial input. At least not in the source code I'm looking at. :)

mcb
Click to expand...

Hi Matt,

I don't know exactly how the software works (computers in general often intimidate and frustrate me), but I do know that if the builder does not have a 430, we almost always hook the portables up to the Txpdrs and it works. If the customer has a 430W then of course the ARINC's work (albeit both work a slight bit differently). Here's what our experience has been...perhaps I mis-spoke just a wee bit!

The portables will kick the Txpdr into ALT from STBY, but not the other way around. With a 430 or similar it'll do both the STBY to ALT and ALT to STBY via ARINC.

At least that's the way it seems to work for us (it's how my 496 works with my Garmin Txpdr). I don't know how all the zero's and ones push electrons around inside the box, but somehow it seems to work.

Cheers,
Stein
 
For me, I'll flip the ALT switch by hand...just like the MD-80 ;)


BUT, I can't fly around without traffic! We MELd the TCAS the other day, and it was like flying half blindfolded.

Thanks again Stein!

Joe
 
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