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Addressing local variables? Redwing Constellation MSFS2024

f16jockey · 2026-06-30T20:57:04Z

I'm trying to assign an axis to the cowl flaps for the Redwing Constellation.Not really an axis, more like a three position switch: if the lever is put into the top 6000, the Cowl Flap value should raise, in the lower 6000 it should lower and in the middle range it should do nothing. As a base, I made a lua script something like while true do local cowl_axis = ipc.readSW(0x66C2) --This is assigned to the correct axis if cowl_axis < -6000 then -- Upper region elseif cowl_axis > 6000 then -- Lower region end ipc.sleep(50) end The above works (my axis acts in reverse, low is 16383 and high is -16384).But I'm stuck where I've written --Upper Region and --Lower Region In the code of the switch (via Behaviours Tool) I see the value of the Cowl Flap is stored in L:1:CowlFlaps_1. I'm unfamiliar with this notation, but it seems to be a local variable (as seen in the attached pics). I'm unable to read or write this variable. I use the same notation as I see it in the code, but this is most probably wrong.For example local current_pos = ipc.readLvar("L:1:CowlFlaps_1") always returns nil. Equally my attempt to write back a higher (or lower) value doesn't work, as could be expected. local new_pos = math.min(100, current_pos + 1.0) ipc.writeLvar("L:1:CowlFlaps_1", new_pos) What's the proper way to access that local variable CowlFlaps_1 ? I hope someone can help me in this, because the Cowl Flaps and Oil Cooler Flaps operation is really dramatic with this aircraft. Best regards,Wim

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Posts: 332

FSUIPC

Admin

July 1, 2026 1:19 pm

(@fsuipc)

Joined: 11 months ago

Here's a demo lua script that shows how to keep a scoped lvar synced with a standard lvar. The script should be auto-ran, preferably only in the profile for the aircraft that contains the scoped lvar that you want to read.

--
-- Demo script on how to sync a scoped lvar to a standard lvar.
-- This allows the lvar to be read or added to an FSUIPC offset.
-- Note that you should not write to this lvar (read-only).
-- To update a scoped lvar, use calculator code or a preset
--
-- This demo script will sync the value of the scoped lvar L:1:CowlFlaps_1
-- to the standard lvar L:MyCowlFlaps_1
--

-- First, create the lvar we are going to use
ipc.execCalcCode("(L:1:CowlFlaps_1, number) (>L:MyCowlFlaps_1, number)")
-- Reload the lvars in the WASM
ipc.ReloadWASM()

-- Wait for the new lvar list to be received
ipc.sleep(200)

-- timer function to sync the scoped lvar with our lvar
function SynScopedLvars(time)
	ipc.execCalcCode("(L:1:CowlFlaps_1, number) (>L:MyCowlFlaps_1, number)")
end

-- Set an event timer to sync the lvars
event.timer(167, "SynScopedLvars")

This would sync the lvar at roughly 6Hz, so at the same frequency as lvar updates are pushed from the FS to FSUIPC7. This implies a maximum delay from between the scoped lvar change and the standard lvar being updated and seen of around 333ms.

Attachment : SyncScopedLvars.lua

This post was modified 21 hours ago 3 times by FSUIPC

f16jockey

Registered

(@f16jockey)

Joined: 2 days ago

Posts: 5

July 1, 2026 7:23 pm

Reply to FSUIPC

@fsuipc I only noticed this post after posting my script. I'll add your ReloadWASM() suggestion at the start of my script 'cos I noticed some issues when running the script in the first session of a cold started sim.

Posts: 5

f16jockey

Registered

Topic starter

July 1, 2026 7:09 pm

(@f16jockey)

Joined: 2 days ago

Thanks for the help, my script is up and running.

My reason for wanting to read the current value of the scoped lvar: I wanted a possibility to control the cowl flaps and oil cooler flaps, without blocking the option to let the Artificial Flight Engineer control them as well.

-- =================================================================
-- REDWING CONSTELLATION - HYBRIDE COWL FLAPS & OIL COOLERS
-- =================================================================
-- COLD START INITIALISATIE: Force the sim to create the global L:Vars
ipc.execCalcCode("0 (>L:MyCowlFlaps_1, number) 0 (>L:MyCowlFlaps_2, number) 0 (>L:MyCowlFlaps_3, number) 0 (>L:MyCowlFlaps_4, number)")
ipc.execCalcCode("0 (>L:MyOilCoolers_1, number) 0 (>L:MyOilCoolers_2, number) 0 (>L:MyOilCoolers_3, number) 0 (>L:MyOilCoolers_4, number)")

-- Give FSUIPC7 some time
ipc.sleep(500)

-- Internal status Cowl Flaps (Axis 4)
local cowl_1, cowl_2, cowl_3, cowl_4 = 0, 0, 0, 0
local cowl_sync = true

-- Internal status Oil Coolers (Axis 5)
local oil_1, oil_2, oil_3, oil_4 = 0, 0, 0, 0
local oil_sync = true

local step = 2.0

while true do
    -----------------------------------------------------------------
    -- 1. COWL FLAPS SECTION (Axis 4 - Offset 0x66C2)
    -----------------------------------------------------------------
    local cowl_axis = ipc.readSW(0x66C2)
    
    if cowl_axis < -9000 then
        -- OPEN
        if cowl_sync then
            ipc.execCalcCode("(L:1:COWLFLAPS_1, number) (>L:MyCowlFlaps_1, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_2, number) (>L:MyCowlFlaps_2, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_3, number) (>L:MyCowlFlaps_3, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_4, number) (>L:MyCowlFlaps_4, number)")
            ipc.sleep(100)
            cowl_1 = ipc.readLvar("L:MyCowlFlaps_1") or 0
            cowl_2 = ipc.readLvar("L:MyCowlFlaps_2") or 0
            cowl_3 = ipc.readLvar("L:MyCowlFlaps_3") or 0
            cowl_4 = ipc.readLvar("L:MyCowlFlaps_4") or 0
            cowl_sync = false
        end
        cowl_1 = math.min(100, cowl_1 + step)
        cowl_2 = math.min(100, cowl_2 + step)
        cowl_3 = math.min(100, cowl_3 + step)
        cowl_4 = math.min(100, cowl_4 + step)
        ipc.execCalcCode(string.format("%f (>L:1:CowlFlaps_1) %f (>L:1:CowlFlaps_2) %f (>L:1:CowlFlaps_3) %f (>L:1:CowlFlaps_4)", cowl_1, cowl_2, cowl_3, cowl_4))
        
    elseif cowl_axis > 9000 then
        -- CLOSE
        if cowl_sync then
            ipc.execCalcCode("(L:1:COWLFLAPS_1, number) (>L:MyCowlFlaps_1, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_2, number) (>L:MyCowlFlaps_2, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_3, number) (>L:MyCowlFlaps_3, number)")
            ipc.execCalcCode("(L:1:COWLFLAPS_4, number) (>L:MyCowlFlaps_4, number)")
            ipc.sleep(100)
            cowl_1 = ipc.readLvar("L:MyCowlFlaps_1") or 0
            cowl_2 = ipc.readLvar("L:MyCowlFlaps_2") or 0
            cowl_3 = ipc.readLvar("L:MyCowlFlaps_3") or 0
            cowl_4 = ipc.readLvar("L:MyCowlFlaps_4") or 0
            cowl_sync = false
        end
        cowl_1 = math.max(0, cowl_1 - step)
        cowl_2 = math.max(0, cowl_2 - step)
        cowl_3 = math.max(0, cowl_3 - step)
        cowl_4 = math.max(0, cowl_4 - step)
        ipc.execCalcCode(string.format("%f (>L:1:CowlFlaps_1) %f (>L:1:CowlFlaps_2) %f (>L:1:CowlFlaps_3) %f (>L:1:CowlFlaps_4)", cowl_1, cowl_2, cowl_3, cowl_4))
        
    else
		-- NEUTRAL - Do nothing but prepare to read the current values
        if not cowl_sync then cowl_sync = true end
    end

    -----------------------------------------------------------------
    -- 2. OIL COOLER FLAPS SECTION (Axis 5 - Offset 0x66C4)
    -----------------------------------------------------------------
    local oil_axis = ipc.readSW(0x66C4)
    
    if oil_axis < -9000 then
        -- OPEN
        if oil_sync then
            ipc.execCalcCode("(L:1:CONST_COOLER_1, number) (>L:MyOilCoolers_1, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_2, number) (>L:MyOilCoolers_2, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_3, number) (>L:MyOilCoolers_3, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_4, number) (>L:MyOilCoolers_4, number)")
            ipc.sleep(100)
            oil_1 = ipc.readLvar("L:MyOilCoolers_1") or 0
            oil_2 = ipc.readLvar("L:MyOilCoolers_2") or 0
            oil_3 = ipc.readLvar("L:MyOilCoolers_3") or 0
            oil_4 = ipc.readLvar("L:MyOilCoolers_4") or 0
            oil_sync = false
        end
        oil_1 = math.min(100, oil_1 + step)
        oil_2 = math.min(100, oil_2 + step)
        oil_3 = math.min(100, oil_3 + step)
        oil_4 = math.min(100, oil_4 + step)
        ipc.execCalcCode(string.format("%f (>L:1:CONST_COOLER_1) %f (>L:1:CONST_COOLER_2) %f (>L:1:CONST_COOLER_3) %f (>L:1:CONST_COOLER_4)", oil_1, oil_2, oil_3, oil_4))
        
    elseif oil_axis > 9000 then
        -- CLOSE
        if oil_sync then
            ipc.execCalcCode("(L:1:CONST_COOLER_1, number) (>L:MyOilCoolers_1, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_2, number) (>L:MyOilCoolers_2, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_3, number) (>L:MyOilCoolers_3, number)")
            ipc.execCalcCode("(L:1:CONST_COOLER_4, number) (>L:MyOilCoolers_4, number)")
            ipc.sleep(100)
            oil_1 = ipc.readLvar("L:MyOilCoolers_1") or 0
            oil_2 = ipc.readLvar("L:MyOilCoolers_2") or 0
            oil_3 = ipc.readLvar("L:MyOilCoolers_3") or 0
            oil_4 = ipc.readLvar("L:MyOilCoolers_4") or 0
            oil_sync = false
        end
        oil_1 = math.max(0, oil_1 - step)
        oil_2 = math.max(0, oil_2 - step)
        oil_3 = math.max(0, oil_3 - step)
        oil_4 = math.max(0, oil_4 - step)
        ipc.execCalcCode(string.format("%f (>L:1:CONST_COOLER_1) %f (>L:1:CONST_COOLER_2) %f (>L:1:CONST_COOLER_3) %f (>L:1:CONST_COOLER_4)", oil_1, oil_2, oil_3, oil_4))
        
    else
		-- NEUTRAL ZONE - Do nothing but prepare to read the current values
        if not oil_sync then oil_sync = true end
    end
    
    ipc.sleep(50)
end

Best regards,

Wim

Posts: 303

FSUIPC Support

Moderator

July 1, 2026 10:12 pm

(@fsuipc-support)

Joined: 8 months ago

That looks ok, but please understand a few things about creating lvars and their access in FSUIPC7. This very much depends on the way lvars are created, and also the WASM settings that automatically discover and force new lvars to interested clients.

First, if you create lvars via FSUIPC standards methods, which are

1. using the lua function ipc.createLvar

2. via writing to offset 0x0D70

then a WASM reload will automatically be issued, but there will still be a delay of around 200ms max before the lvar becomes available.

If lvars are created any other way, e.g. by sending calc.code strings, created by 3rd party apps or even MSFS itself, then these will not be "known" to FSUIPC unless you issue a 'reload' command to the WASM.

There are various WASM parameters that control the scanning for lvars and thus the visibility of lvars in FSUIPC, but in the default configuration the scanning for new lvars stops 2 minutes after aircraft load. So if any lvars are created after this period, unless they are explicitly created via the FSUIPC functions already mentioned, then they will not be visible until a WASM reload call has been made (by any client).

Regards,

John

This post was modified 12 hours ago by FSUIPC Support

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