PDA

View Full Version : GRT Autopilot connection


Cleco 97
01-15-2020, 09:11 AM
Iam finishing up my wiring and would like to connect my autopilot servo wiring (GRT A/P servos) to my GRT EFIS sport EX. According to the wiring diagrams, I need a serial in and serial out for them to operate. My problem is that I dont have any available for this purpose. My question is can I splice into one of the 3 serial ports to supply the info to the servos, or do I have no other option than to purchase a serial port expander from GRT? The EFIS I purchased came with 3 serial ports, but I have them filled with the GRT EIS, Garmin 327 Xponder, and the Vertical Power electronic circuit breakers. After reading this, it would make sense to me that I would need to get the expander, but think Ill just check here to see if any of you have come across this issue, or have any other ideas.

Thanks for the help!

lr172
01-15-2020, 09:44 AM
You can't share the serial ports. AP will need a dedicated RS-232.

Lars
01-15-2020, 10:10 AM
Another possibility would be to send the EX back to GRT and have them install the optional serial ports, for a total of 6. That would simplify your wiring, since the serial port expander will consume one port on the EX.

Cleco 97
01-15-2020, 10:26 AM
That?s what I figured, but thought I would see if you guys had any other ideas. Thanks a boat load for the help!!

Tailwind/RVGuy
01-15-2020, 12:50 PM
I recently installed a GRT Sport EX (with only 3 ports) and a GRT auto pilot. I also have the GRT EchoUAT/Safefly GPS with serial port expander but have not used it. If your GRT EIS is panel mounted, you could consider not connecting the EIS to your EFIS and just monitor it via the existing display on the EIS. That would free up the in and out ports for the AP. Granted you lose some functionality of recording information from the EIS on your EFIS but I decided it was OK to use my EIS as is.

Also if you don't already have ADSB out, you could buy the EchoUAT/Safefly GPS from GRT and that then comes with the serial port expander. Mine "sniffs" my KT76A transponder and am assuming you would hard wire your Garmin 327 so don't know the port requirement for that.

Keith

DMFenster
01-15-2020, 04:51 PM
The GRT EIS and Garmin 327 Xponder both use 9600 baud so you can use one serial port for both devices. The EFIS gets data from the EIS, and the EFIS sends data to the GTX.

[Serial port on the EFIS] - the EIS to IN and the GTX to OUT on the same number serial port.

Dave

BobTurner
01-15-2020, 06:58 PM
The GRT EIS and Garmin 327 Xponder both use 9600 baud so you can use one serial port for both devices. The EFIS gets data from the EIS, and the EFIS sends data to the GTX.

[Serial port on the EFIS] - the EIS to IN and the GTX to OUT on the same number serial port.

Dave

+1. The rule is, on any given "port", both "in" and "out"must run at the same speed ("baud rate"; 4800, 9600, etc.). But the "format" can be configured individually for the "in" and "out" data. If you have 2 different devices that need the same "in" data (same baud rate, same format) then one "out" can be split/spiced to provide this data to the 2 different "in" ports.
Not having enough RS232 serial ports is not an uncommon problem. It's surprising how many you can end up using. Before going any further, try to anticipate any/all future needs. ADSB-in (traffic/wx) data? VOR/ILS or external GPS data to the EFIS? Count up how many ports you need (use the rules in the first paragraph) then decide what if any action is required.
BTW, I urge you to display the EIS data on the EFIS if at all possible. The bar graphs are much easier to interpret than the EIS presentation(s).

Funguy
01-15-2020, 09:14 PM
There is no need to send in the Sport Ex to upgrade to the additional 3 serial ports. This is a software only upgrade. The hard wiring is already there and just needs to be enabled for a small fee of US$200.00.

Cheers, Sean

Lars
01-15-2020, 10:37 PM
There is no need to send in the Sport Ex to upgrade to the additional 3 serial ports. This is a software only upgrade. The hard wiring is already there and just needs to be enabled for a small fee of US$200.00.

Cheers, Sean

...for the win. Thanks for that tidbit! Helps me too :D

Cleco 97
01-16-2020, 04:37 AM
Good info as usual here. I talked to GRT and explained my situation and I will be doing as you have suggested ie. making a $200 donation so that I can use the other serial ports that had been disabled. Not exactly sure what I steps I will need to perform to enable the additional ports, but sounds like it will just be a software update via USB I presume. The only other port I would need to use is for the ADS-B, which I will be making another donation in the future to what appears to be in the $1500 area. GRT says that the Uavionix/echo device they sell will be easy to connect with the addition of the additional serial ports.
P.S. I do plan on keeping the EIS connected to EFIS for the very reason you mentioned....much easier to see.

Funguy
01-16-2020, 08:44 AM
The process to enable the additional serial ports just requires that you enter a code and voila, they are enabled. It's the same process to add additional analog inputs and some of the other features. The hardware is already there, you are paying for the added value of the features to enable... There are a couple of items that need a screen return to upgrade like touchscreen and angle of attack.

Cheers, Sean