How to Control Battery 1 & 2 in Asobo A320neo?

[BergerRainer]

Hi Max,

First of all, a big thank you for your WASimCommander project, which you’ve shared here on GitHub. It’s truly impressive how well thought out and comprehensive it is — and how many possibilities it opens up for custom hardware integration in MSFS2020. You have our full respect for the time and effort you’ve clearly invested!

We’ve successfully set up your project — both the WASM module (it shows up in the WASM Debug window without any red error lines) and your test application are running without any issues on our side.

However, we haven’t yet managed to turn Battery 1 and 2 on or off in the Asobo A320neo using WASimCommander.

So our question is:
Is it in principle possible to control Battery 1 and 2 in the Asobo A320neo via WASimCommander in MSFS2020? And if so, how exactly would we need to do it (e.g., which RPN command, variable, or method)?

We’d really appreciate any advice or example you could share!

Thanks again for your amazing work, and greetings from germany

Rainer

[mpaperno]

Hi Rainer,

Thanks for the kind words, happy to make this project useful! 💐

As for the A320 batteries... I don't really know :)
There is always the "discovery" phase with each model, it seems, with some just not using typical standard events/sim vars. The 320neo seems kinda infamous for that.

Here's one resource that might be useful, check out the RPN for the two battery events here (not tested personally, may not work):
https://hubhop.mobiflight.com/presets/?aircraft=A320&vendor=Asobo&system=Electrical

Or maybe this post:
https://forums.flightsimulator.com/t/a320-neo-battery-switch/633519
That one talks about using InputEvents via SimConnect (which are aka "B" variables). I just learned that in FS20 we can set them with RPN code using F type "variable", aka the "Function Library," as mentioned here:
https://docs.flightsimulator.com/msfs2024/flighting/html/6_Programming_APIs/Reverse_Polish_Notation.htm#FunctionLibrary
But I haven't tried it yet. In FS24 B vars can be used directly in RPN code (eg. 1 (>B:MASTER_BATTERY_ON_Set), but that doesn't work in FS20.

More....
https://forum.simflight.com/topic/92509-a320-battery/

Then there's also possible confusion about how those switches work in the first place (not even remotely, just using in-sim cockpit interactions):
https://forums.flightsimulator.com/t/a320-battery-switches/467811

Sorry I can't give you a more definitive answer, but hope that helps.

Cheers,
-Max

[mpaperno]

I forgot there's a "v2" of the 320neo... but if we're talking about the original, I did confirm the RPN code from HubHop seems to work.

(A:ELECTRICAL MASTER BATTERY:1, Bool) ! if{ 1 (>K:TOGGLE_MASTER_BATTERY) } 
1 sp0 10 (>A:BUS LOOKUP INDEX, Number) (A:BUS CONNECTION ON:6, Bool) l0 != if{ 
10 6 (>K:2:ELECTRICAL_BUS_TO_BUS_CONNECTION_TOGGLE) }

It is simpler than it may look and could actually be performed w/out RPN. To break it down...

(A:ELECTRICAL MASTER BATTERY:1, Bool) ! if{ 1 (>K:TOGGLE_MASTER_BATTERY) }
If SimVar "ELECTRICAL MASTER BATTERY:1" is 0 then triggers "TOGGLE_MASTER_BATTERY" Key Event with a value of 1.
(Seems like this could be replaced with "MASTER_BATTERY_ON" or "MASTER_BATTERY_SET" events to ensure that is always ON, and simplify the code.)

1 sp0 10 (>A:BUS LOOKUP INDEX, Number) (A:BUS CONNECTION ON:6, Bool) l0 != if{
Sets "BUS LOOKUP INDEX" SimVar to 10 and then reads the state of connection at index 6 with "BUS CONNECTION ON:6". If that is 0/false, then...

10 6 (>K:2:ELECTRICAL_BUS_TO_BUS_CONNECTION_TOGGLE)
Triggers that Key Event with two values, 6 and 10, which apparently correspond to Bus Index 10 and Connection ID 6.
(If using WASimClient::triggerEvent() or SimConnect_TransmitClientEvent_EX1(), the 10 is the first event value and 6 is the 2nd.)

If you trigger the same event again with same values, the battery turns off.

So you can see most of the code is just checking if the connection needs to be made in the first place.

Using Bus Index 11 (instead of 10) controls the 2nd battery.

Some of this can be figured out by looking at the sim's Debug Behaviors window -> Systems tab -> "Show electrical system debug" and then examining the "Bus Connections" tab in the new window that opens. Though I'm still not sure how one comes up with the Circuit index (6, in this case).

So far I haven't been able to get anything like
1 'ELECTRICAL_Battery_1_Set' (>F:InputEvent)
to work with FS20, so that might have been optimistic of me to mention it earlier.

Cheers,
-Max

[BergerRainer]

Hello Max,

First of all, thank you very much for your quick and detailed response.

I was away for a few days riding motorcycles with friends, so please excuse the delayed reply. I definitely didn't want to leave your efforts unanswered—especially since your solution may also be of interest to other users of WASimCommander.

Your email, particularly the second part, was the game changer and brought me to the goal. Thanks to your help, Battery 1 and 2 can now be toggled without any issues.

Here, for others, is how I implemented your email into my code:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
struct PowerData
{
    public int extPowerAvailable;
    public int extPowerOn;
}

static void Main(string[] args)
{
    Console.WriteLine("MSFS Serial Bridge started...");
    InitSerial("COM3", 9600);

    try
    {
        simconnect = new SimConnect("MSFS_SerialBridge", hWnd, WM_USER_SIMCONNECT, null, 0);
        simConnected = true;
        Console.WriteLine("SimConnect connected.");

        // **
        _wsimclient = new WASimClient(simconnect);
        RegisterBatteryToggleEvents();
        // **

        // Event handler for incoming SimConnect data
        simconnect.OnRecvSimobjectData += SimConnect_OnRecvSimobjectData;

        // Switch EXT PWR
        simconnect.MapClientEventToSimEvent(EVENT_ID.EXTERNAL_POWER_TOGGLE, "TOGGLE_EXTERNAL_POWER");
        simconnect.AddClientEventToNotificationGroup(GROUP_ID.GROUP0, EVENT_ID.EXTERNAL_POWER_TOGGLE, false);

        simconnect.RegisterDataDefineStruct<PowerData>(DATA_DEFINE_ID.DEFINITION_1);

        // Initial request
        simconnect.RequestDataOnSimObject(DATA_REQUEST_ID.REQUEST_1, DATA_DEFINE_ID.DEFINITION_1, SimConnect.SIMCONNECT_OBJECT_ID_USER, SIMCONNECT_PERIOD.SECOND, SIMCONNECT_DATA_REQUEST_FLAG.DEFAULT, 0, 0, 0);
    }
    catch (COMException ex)
    {
        Console.WriteLine("Failed to connect SimConnect: " + ex.Message);
    }

    Console.WriteLine("Running – press Esc to exit...");

    while (!(Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.Escape))
    {
        if (simConnected)
        {
            simconnect.ReceiveMessage(); // <-- crucial!
        }

        System.Threading.Thread.Sleep(50); // CPU friendly
    }

    Cleanup();
}

// **
static void RegisterBatteryToggleEvents()
{
    if (_wsimclient != null)
    {
        _wsimclient.registerEvent(new RegisteredEvent(1001,
            "(L:BAT1_STATUS, Number) 1 == if{ 0 (>L:BAT1_STATUS) } els{ 1 (>L:BAT1_STATUS) } 1 (>B:ELEC_BAT_1_PB, Number)",
            "My.ToggleBAT1"));

        _wsimclient.registerEvent(new RegisteredEvent(1002,
            "(L:BAT2_STATUS, Number) 1 == if{ 0 (>L:BAT2_STATUS) } els{ 1 (>L:BAT2_STATUS) } 1 (>B:ELEC_BAT_2_PB, Number)",
            "My.ToggleBAT2"));

        _wsimclient.setOrCreateLocalVariable("BAT1_STATUS", 0.0);
        _wsimclient.setOrCreateLocalVariable("BAT2_STATUS", 0.0);

        Console.WriteLine("BAT1 & BAT2 events registered.");
    }
}
// **

static void SerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    try
    {
        string line = serialPort.ReadLine().Trim();
        Console.WriteLine($"Received: {line}");

        if (!simConnected) return;

        if (line == "BATT_TOGGLE")
        {
            if (_wsimclient != null)
            {
                try
                {
                    // **
                    _wsimclient.transmitEvent(1001); // Toggle BAT1
                    Thread.Sleep(100);
                    _wsimclient.transmitEvent(1002); // Toggle BAT2
                    Console.WriteLine("BAT1/BAT2 toggled via custom events.");

                    Thread.Sleep(100); // small buffer

                    // Read LVars
                    double bat1, bat2;
                    bool ok1 = _wsimclient.executeCalculatorCode("(L:BAT1_STATUS, Number)", CalcResultType.Double, out bat1) == HR.OK;
                    bool ok2 = _wsimclient.executeCalculatorCode("(L:BAT2_STATUS, Number)", CalcResultType.Double, out bat2) == HR.OK;

                    if (ok1 && ok2)
                    {
                        _batteriesAreOn = (bat1 == 1 && bat2 == 1);
                        Console.WriteLine($"BAT status: BAT1={bat1}, BAT2={bat2} → batteriesAreOn={_batteriesAreOn}");
                    }
                    else
                    {
                        Console.WriteLine("Could not read LVars for BAT1/BAT2.");
                    }
                    // **
                }
                catch (Exception ex)
                {
                    Console.WriteLine("Error toggling batteries via WASimCommander: " + ex.Message);
                }
            }
            else
            {
                Console.WriteLine("WASimClient is not initialized.");
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine("Error reading from COM: " + ex.Message);
    }
}

I hope—and would be glad—if this code helps someone else as well.

Max, is it okay for you if I reach out to you again in case I encounter further issues with other Korries?

Thanks again!"

Best regards,
Rainer

[mpaperno]

Hi Rainer,

No worries, sounds like you had more fun than MSFS coding!

Happy that helped. Feel free to "upvote" anything you think other may find useful. I suppose eventually the AIs will find this and claim credit anyway... 😅

Thanks for the code. I added a little formatting around it, hope you don't mind.

I like your use of custom calculator events (registerEvent())... nice! Exactly what that feature was designed for.

For reading L vars I'd personally prefer the dedicated get[Local]Variable() method(s)... much more efficient than RPN. Or just subscribe to them (saveDataRequest()) and you could update _batteriesAreOn whenever those change, asynchronously (no sleeping, yay!). (Just be aware the data change events are delivered from a separate thread, which could matter down the line if you use this in a GUI app.)

Feel free to ask away... :) Here or on Discord. I'm definitely not an expert in all the individual models though, since it seems like each one has its quirks (FS-X was so much simpler). But happy to help when I can.

Cheers,
-Max