DanH

DanH

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The GRT gang has gone to S&F (which of course they should) and thus they are not available this week to answer the usual dumb builder questions. Can someone with the same system cover a few items so I don't lose time?

Subject is a GRT Sport SX and EIS 4000.

1. Is there an engine cylinder graphic display (top view of engine) on the Sport, or just bar graphs?

2. Anybody have a wiring diagram for autopilot GPS source switching? (through the EFIS or bypass the EFIS)

3. Both EIS and EFIS have "audio out" pins. Does does either actually have an audio output at this time?

4. The Sport has 6 Aux outputs? (says 4 and 6 on different manual pages)

5. EIS pins 3 and 4 are marked "N.C.", which usually means "Normally Closed". What is their purpose in this application? (I'm curious)

6. EFIS pin 21 on connector A is "clock power" and they ship with a wire for it, but the manual says no clock power needed. Which is correct, power or no power?

7. Anybody have documentation for the backup battery? I assume there is no auto-switching in the event of avionics bus power loss and I need a switch to bring the battery online? What do you use for a charge rate monitor? (there is a pin for it)

8. Where do you get a backshell for the 37 pin d-sub?

Thanks
 
Dan,

I have a dual Sport SX+ setup with EIS.. I can try to answer some of your questions.. see inline:

DanH said:
The GRT gang has gone to S&F (which of course they should) and thus they are not available this week to answer the usual dumb builder questions. Can someone with the same system cover a few items so I don't lose time?

Subject is a GRT Sport SX and EIS 4000.

1. Is there an engine cylinder graphic display (top view of engine) on the Sport, or just bar graphs?

No

2. Anybody have a wiring diagram for autopilot GPS source switching? (through the EFIS or bypass the EFIS)

Serial only? (no ARINC?) It's just a DPST switch -- feed serial out from EFIS to one pole, and feed serial out from GPS to the other pole. Switch's "out" goes to A/P. This sounds more complicated than it is..


3. Both EIS and EFIS have "audio out" pins. Does does either actually have an audio output at this time?


IMHO, not needed. Also, believe that EFIS does not actually have it implemented. I didn't use either.. don't really think it's needed.. Have flown in airplane that has it.. didn't think it was all that important to have it.. visual warning will get your attention quickly.


4. The Sport has 6 Aux outputs? (says 4 and 6 on different manual pages)

Uhm.. what exactly are you referring to? Serial ports? Standard SX has 4 Serial ports. SX+ (the unit that has upgraded CPU/GPU which is capable of running synthetic vision has 5 Serial ports). You're not confusing this with 6 Aux inputs into EIS by any chance?


5. EIS pins 3 and 4 are marked "N.C.", which usually means "Normally Closed". What is their purpose in this application? (I'm curious)

6. EFIS pin 21 on connector A is "clock power" and they ship with a wire for it, but the manual says no clock power needed. Which is correct, power or no power?

Last I checked this was not implemented, hence don't bother putting a wire in that pin. Not really needed in 99.999% of cases.


7. Anybody have documentation for the backup battery? I assume there is no auto-switching in the event of avionics bus power loss and I need a switch to bring the battery online? What do you use for a charge rate monitor? (there is a pin for it)

There's a wiring diagram for backup battery on their site..


8. Where do you get a backshell for the 37 pin d-sub?

Didn't get one from them? I'd try Radio Shack..


Thanks
Click to expand...
 
Good responses already. I'll just add that "N.C." in the GRT tables generally means "Not Connected". I agree that the clock power is unnecessary - never found that it did anything. GRT is usually great about backshells - if you don't find one before SNF ends, I bet they'll send you one....

They usually make Sandy stay up in Grand Rapids when everyone else goes to the shows - maybe she decided she'd had enough of winter this year?!

Paul
 
Three cheers for Sandy ...

...she's ALWAYS superbly helpful when I call or e-mail GRT. Given the l-o-n-g winter we had in the Midwest this year, I hope she's sunning herself in Lakeland and having a great time! :D:D
 
Audio out

I have the Audio out from the EIS (not the Sport) connected to my Audio Panel (non-muted input). It puts out a 'beep' tone in synch with the blinking light. I don't believe the Sport Audio is implemented (never tried it).
I concur that 'clock power' is not implemented on the Sport. It's clock is synched with the GPS, if it is in the data stream. My 300XL does not put out the clock signal so I added a 'hockey puck' second GPS which does. Their internal GPS does as well as probably all other GPS's but the 300XL.
I got the shell for the 37 pin Dsub from GRT - my Radio Shack didn't have them.
The AUX ports are for whatever sensors you use - I have: MP, Fuel levels (1 port each), Coolant Temp, GB temp and Aux Batt voltage.
The errant 6 serial ports in the manual (it's 4 for the Sport) is because they did a lot of cut/paste from the Horizon docs for the Sport.
As for backup battery, if both power inputs are connected, the unit will take power from whichever source has voltage, no switching required. They are diode protected internally so the good one won't feed the dead one.
 
Ahhh, thanks Dennis. I was hoping for a warning beep.

Thought about the suggested "bypass the EFIS" switch. Ya'll check me; this should get it done:



One catch to the above; the Trio AP wiring diagram shows "GPS Data" (pin 7) and "GPS Data Ground" (pin 8) as a twisted pair. The above only deals with the GPS data. I have no idea what to do with the pin 8 connection.

They're labeled "Avlink or NMEA 0183 Data Input" on the diagram. A schedule lists them as an RS232 serial data input and a "GPS data return".

Hmmm.....I'm guessing "ground" has a slightly different meaning in the world of serial communications. Anyone care to educate me?
 
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DanH said:
Ahhh, thanks Dennis. I was hoping for a warning beep.

Thought about the suggested "bypass the EFIS" switch. Ya'll check me; this should get it done:



One catch to the above; the Trio AP wiring diagram shows "GPS Data" (pin 7) and "GPS Data Ground" (pin 8) as a twisted pair. The above only deals with the GPS data. I have no idea what to do with the pin 8 connection.

They're labeled "Avlink or NMEA 0183 Data Input" on the diagram. A schedule lists them as an RS232 serial data input and a "GPS data return".

Hmmm.....I'm guessing "ground" has a slightly different meaning in the world of serial communications. Anyone care to educate me?
Click to expand...
I have all my serial grounds, radio grounds, EFIS, EIS grounds going to a common point (Dsub connector) which is then connected to my forrest of tabs ground. I believe this is the way it is currently recommended in the AeroElectric connection. For this equipment 'common' is the important concept. It's usually grounded, to the airframe typically through the equipment chassis as well, but I'll contend that it will work even if it weren't.
In your diagram, if the EFIS, AP and GPS, and serial grounds go to a common point, it will work fine.
 
<<For this equipment 'common' is the important concept.>>

Thanks Dennis. Sounds like single-wire serial connections typically depend on common connection through chassis grounds. In this case, Trio merely went to the trouble of ensuring a serial common via a dedicated wire. Fair summary?
 
DanH said:
Thanks Dennis. Sounds like single-wire serial connections typically depend on common connection through chassis grounds. In this case, Trio merely went to the trouble of ensuring a serial common via a dedicated wire. Fair summary?
Click to expand...

You've got it right Dan - I run all my avionics (signal) grounds together at a common point, and then that is easily grounded to the airframe - and just as easily ungrounded if I have a nice issue (which I haven't).

Your drawing will work, but is needlessly complicated. Short of relearning how to use a drawing program, I'll just say that all you need is a single pole, double through switch - hook up the two "sources (GPS Direct and EFIS) to the poles, and the Autopilot to the center, and you can select either source to drive the A/P. Been flying that way for years - simple, and it works.

Paul
 
Ironflight said:
You've got it right Dan - I run all my avionics (signal) grounds together at a common point, and then that is easily grounded to the airframe - and just as easily ungrounded if I have a nice issue (which I haven't).
Click to expand...

Thanks Paul.

Your drawing will work, but is needlessly complicated......all you need is a single pole, double through switch - hook up the two "sources (GPS Direct and EFIS) to the poles, and the Autopilot to the center, and you can select either source to drive the A/P.
Click to expand...

Depends on your goal, switching or isolation. The SPDT scheme leaves an intact connection between the GPS and the EFIS even when the switch is connecting the GPS directly to the autopilot (drawings below). The DPDT scheme fully isolates the EFIS (diagram in previous post).



 
Dan, I'm agreeing with Paul that the original drawing is overly and unnecessarily complicated.

Having said that, neither of the subsequent two drawings you posted are "correct" -- with second one being better but still missing wire from EFIS to the switch.

What "isolation" are you looking for here that's not achieved with SPDT? EFIS wont' back-feed into GPS..
 
Now I understand your goal Dan, and you can do it for isolation. But I can tell you that in the years I have been flying the Val, I have thrown the switch from "EFIS" to GNS" exactly....well, maybe once or twice during testing. I've never had the need to drive the A/P direct from the GPS. Still like having the switch though...just in case!

the way mine is hooked up, the EFIS is always connected to the GPS line. The A/P is either EFIS or GPS - if it is switched to the GPS, it doesn't even know the EFIS is there, and like Rad said, the EFIS isn't going (realistically) to disable the line from the GPS.

Paul
 
I hear you, although it's hard to see how fully isolating the EFIS is complicated.....it has one additional wire. I swear, count 'em ;)
 
Oh the weight!

DanH said:
I hear you, although it's hard to see how fully isolating the EFIS is complicated.....it has one additional wire. I swear, count 'em ;)
Click to expand...
Yeah, but it also has that way more complicated and heavier DP switch :rolleyes:
 
Hi Dan,

I'm kinda late to this party, but here's a thought. According to Greg at the GRT booth last week, the GRT Sport will listen to just about any $50 'puck' type GPS receiver with serial output. My tentative plan, after talking to Greg, is to drive the Sport with one of those. Then the Autopilot can listen to either the Sport, or to whatever other GPS is installed in the plane, using the simple SPDT switch others have mentioned. That way, there's full redundancy; if something goes wrong with the Sport's output, there's no guessing on whether it's the Sport or its GPS causing the problem.

If the 'other' GPS needs to feed the Sport for other reasons, then the 'puck' can be the backup to the autopilot; same switch arrangement.

Charlie
 
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