This recently from a reader, and I thought my reply (while not completely thorough) might be of help to others. I’ve made some minor edits from the original.
I bought the Saitek Multi Panel and Switch Panel but I can’t get them to work with the A2A 182 or 172. I read about Spad.NeXt but am not comfortable using it. Is there another way to get Saitek and A2A to get along?
SPAD.neXt is the best I’ve found. Part of the key is understanding profiles and snippets. Load up your 172 or 182, and then in SPAD.neXt go to the profiles page and look at the available online profiles. There should be some that others have made for the A2A planes. Download one and assign it as the profile for the plane in Prepar3d. You do this all in SPAD.neXt, and it’s really pretty easy once you get used to it. This should have the right codes for most of the switch panel and multi panel switches. You can also go to one of those instruments – say the switch panel – click on a button on the panel (say, fuel pump), and then click snippets. You can then download online snippets for that switch, or for the entire panel. I think I published my switch and multipanel snippets – they’d be listed with “basementflyguy” as the author. Try this and see if it helps. Someone before you has surely already done the work of figuring out the variable assignments and you just need to find the profile or snippet online … [and note that you need to be a paid user of SPAD.neXt to have access to the library of online profiles and snippets, which is well worth it in my opinion]
And if you decide to roll your own, it’s really not too difficult. Every function in the sim has a command or variable associated with it – either a “simconnect” command (which is most of the stock functions) or an “LVAR” variable, which are custom variables like those in the A2A aircraft. To program a switch (say, the fuel pump), you click on it, pick if you want it switched up or down (for example), then assign the condition to be true when it’s flipped. You can pick a SimConnect command, a LVAR variable setting, turning on a light on the Saitek BIP panel, or several other things to result from the switch being thrown or button pushed.
The commands and variables are searchable, so you could select “LVAR,” it pulls up a big list, and then you can type “pump” in the search box and all the LVAR variables that have “pump” in their name pop up. You see one listed “TOGGLE_ELECT_FUEL_PUMP1,” and you suspect that’s the right one. Select it, leave the assigned value at “0” (because it’s a toggle – with other variables, like barometric pressure, the variable could have a real value like 2995 – and the SPAD.neXt screen shows you in the lower left corner of the variable list screen what the possible values are), click OK and that switch is now assigned. Flip it and it will toggle the fuel pump.
For the A2A aircraft most of the switches use LVARS rather than the stock SimConnect commands. You can find PDFs with all of those variables here: http://www.ontheglideslope.net/2016/07/08/a2a-cessna-172-182-piper-180-lvar-lists/
I know a lot of folks struggle with the battery and alternator switches. For the A2A Cessnas the variables are:
Assign those variables to those switches in SPAD.neXt to those two switches on the switch panel (with values of 0 for off and 1 for on) and you should be good to go. [Also note that you need to ensure SPAD.neXt is configured to read LVAR variables, and this is an option you set on the SPAD.neXt settings screen].
One last word: depending on when you have saved a scenarios some of the variables may already be “on” when you load the scenario, even if the switch is off. I often open the “mini panel” instrument menu in P3D just to ensure everything is clicked to off with all my switches off when I start a flight.
Some day I will probably write a little how-to on SPAD.neXt and A2A. Until then, I hope this helps.