# Data Exchange with the EdgeTX Model Setup In general terms, there are two different types of data that can be exchanged with EdgeTX: * Values, which generally fall on a scale between -1024 and 1024, also sometimes reported as -100% to 100%, e.g. for mixer values and channel outputs. * Switches, which are either `true` or `false.` A specific data source type, e.g. Global Variables, can be indexed directly with an index that starts with 0 for the first one. This can be a little confusing, as e.g. GV1 for FM0 is read with [`model.getGlobalVariable(0, 0)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/model-functions-less-than-greater-than-luadoc-begin-model/getglobalvariable.md), because GV1 is the first global variable, and FM0 is the first flight mode. But as long as you remember that all direct indices start with 0 for the first one, you should be fine! Global Variables is a *value* data source that can return a value between -1024 and 1024. Examples of value sources are: * Global Variables * Sticks, sliders and knobs * Trim values * Input lines * Channel outputs * Trainer channel inputs * Telemetry sensors There is a way to access a value of *any* such type with a *meta-index*. You use the function [`getFieldInfo(name)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getfieldinfo.md) where `name` can be any of the valid source names listed [here](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getfieldinfo.md). It returns a table with a description of the value source, including the field `id,` which is the meta-index. You can use `id` with the function [`getValue(id)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getvalue.md) to read the current value. You can also use `name` directly, but this is less efficient, as EdgeTX does a linear search for the name every time it is called. Therefore, the procedure of first extracting the meta-index from `getFieldInfo(name).id`, and then using that, is recommended. For switches, [`getLogicalSwitchValue(index)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getlogicalswitchvalue-id.md) uses a direct index to read this specific type of switch sources, again using the `index` 0 for LS1 etc. But there are also several types of switch sources, such as: * Logical switches * Switch positions, testing if a physical switch is in a particular position, e.g. `SA↑`. * Trim buttons * Transmitter and telemetry activity You can find the meta-index of a particular switch source with [`getSwitchIndex(name)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getswitchindex-positionname.md), where `name` is exactly the name that you see in the radio menus where you can select a switch source. You can read the current value of a switch source with [`getSwitchValue(index)`](https://github.com/EdgeTX/lua-reference-guide/blob/main/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/getswitchvalue-switchindex.md) as a `true`/`false` value. It can be very confusing that some source can be read both as a value and as a switch. As an example, elevator trim can be read as the current value of the *trim*: ```lua local id = getFieldInfo("trim-ele") local eleTrim = getValue(id) ``` Or it can be read as the current value of the *trim button position*: ```lua local idUp = getSwitchIndex(CHAR_TRIM .. "Eu") local idDown = getSwitchIndex(CHAR_TRIM .. "Ed") local eleUp = getSwitchValue(idUp) local eleDown = getSwitchValue(idDown) ``` These are really two different things, as the elevator *trim* is an internal value stored by the radio, which is changed with the trim button, and the button is a physical button. But it can also be a more direct comparison, e.g. the 3-position switch B, which can be read as a *value* source with: ```lua local idB = getFieldInfo("sb") local swBvalue = getValue(idB) -- a value of -1024, 0 or 1024 ``` Or the current position of switch B can be read with: ```lua local idBup = getSwitchIndex("SB" .. CHAR_UP) local idBdown = getSwitchIndex("SB" .. CHAR_DOWN) local swBup = getSwitchValue(idBup) local swBdown = getSwitchValue(idBdown) ``` Hopefully, these examples illustrated the differences between *values* and *switches*, and showed how these can be retrieved in a Lua script. You can also send data the other way: from Lua to the EdgeTX model setup. To send a *value*, use a global variable: `model.setGlobalVariable(index, fm, value)`. If you use the default GV setting, where all other flight modes use the value of FM0, then you can use 0 for `fm`. To send a *switch*, setup a `STICKY` type logical switch, and then use `setStickySwitch(index, true/false)`. The following table gives an overview of the Lua API functions that can be used to exchange data with the EdgeTX model setup. | Function | Description | | ---------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `getFieldInfo(name)` | Gets the meta-index of a *value* source with `name`. | | `getValue(index)` | Gets the current value of a source, where `index` is from the above. | | `getFlightMode()` | Returns the current flight mode number and name. **Do not** confuse with `model.getFlightMode`, which is a completely different function! | | `model.getGlobalVariable( index, fm)` | Read the value of a global variable between -1024 and 1024. You can use the above to get the current flioght mode for `fm`, or you can setup the GV to always use the value from FM0. | | `model.setGlobalVariable( index, fm, value)` | Sets the value of a global variable. | | `setTelemetryValue(id, subID, instance, value, ...)` | This function can send data from Lua to a telemetry sensor. If it is running, then the sensor will show up with Discover Sensors. This can be used to log values generated by Lua. | | `getLogicalSwitchValue( index)` | Get the value of a logical switch. | | `setStickySwitch(id, value)` | Set the value of a `STICKY` type logical switch. | | `getSwitchIndex(name)` | Get the meta-index of a switch source with `name`. | | `getSwitchName(index)` | Get the name of a switch source. | | `getSwitchValue(index)` | Get the value of a switch source. | | `getPhysicalSwitches()` | Get a list of physical switches on the radio. Can be used to make a selection list. | | `getShmVar(index)` | Get the value of a shared memory variable. These are little "mail boxes" provided as a way to send data between Lua widgets and other Lua scripts like Mixer and Function scripts. | | `setShmVar(index, value)` | Set the value of a shared memory variable. | | `model.setTimer(timer, value)` | Set the timer to `value`. | | `model.getTimer(timer)` | Read the timer. | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://luadoc.edgetx.org/lua-api-programming/data-exchange-with-the-edgetx-model-setup.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.