Garmin 496 connection to EFIS 100

[Marvin]

I have a new Evektor Sport Star with an EFIS 100, Garmin 496, SL 30 Com, and communication data port on the panel.
The wind arrow and the HSI do not function, and Evektor tells me the reason is that there cannot be a wiring connection to the D100 from both the 496 and the data port at the same time.
Does anyone know if this is true? If so, couldn't there be a simple switch to alternate between the 496 and the data port?

Marvin Mixon

 

[Etienne]

Yes, that can be done. In fact, I'm busy building my panel to have a matrix connection between 2 gps's, a D100, a full computer and an external data port on the front of my panel, so that any instrument can connect to any other instrument. This uses 5 rotary switches though...

So, what do you want to speak to what?
496 --> D100 (obviously)
496 <-> External port?
D100 <-> External port?

If you want all of these, then I'd suggest a double-pole double-throw switch...

Common pins (centre pins on most switches) of the switch go the external port. Position 1 goes to the D100, and Position 2 goes to the 496. Then because you only need uni-directional comms between the 496 and D100, and the D100 is intelligent enough to ignore data it doesn't understand, you can put a Schottky diode or something similar between the 496 send and the D100 receive wires. This can be done across the pins at the back of the switch...

If you are going to be upgrading firmware on the 496, I'd still suggest turning off the D100 though, just in case

Here's a picture of the circuit diagram (sorry, it's hand-drawn and webcam'ed - no scanner or cad software here!)

Thanks
Etienne

 

[Marvin]

Thanks Etienne,

I will not need to connect the 496 to the panel port. So I need only a connection between the 496 and the D100, and separately the existing D100 connection to the panel port.

Could I impose on you to draw such a circuit and suggest the switch type?

Marvin Mixon

 

[Etienne]

OK, that's even easier then...

Use a Double-Pole Single-Throw switch.

Common goes to the D100 receive
Position 1 goes to the port's incoming data pin
Position 2 goes to the 496 send wire

 

[Etienne]

Here's the diagram...

Good luck!
Etienne