> For the complete documentation index, see [llms.txt](https://xm2labs.gitbook.io/slg20-retractable-landing-gear-altax-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://xm2labs.gitbook.io/slg20-retractable-landing-gear-altax-manual/operation/parameter-system.md).

# Parameter System

Parameter System for XM2 Labs SLG-20 Retractable Landing Gear

The SLG-20 parameter system is stored on persistent memory. The parameter system is primarily used to store calibration data.

Parameters are loaded from persistent memory into RAM on boot. Parameters can be updated in RAM and tested without saving to persistent memory. The parameter system is accessed using the console interface as described in the [console interface section](/slg20-retractable-landing-gear-altax-manual/console-interface/using-the-console-interface.md) of this manual.

## Parameter List

| Parameter   | Default Value | Description                                                                                                                                                                                                                                                                                                                                                                                                                    |
| ----------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| ee\_check   | 26            | This parameter is used to check if the EEPROM is valid and the legs are calibrated. A value of 27 indicates the EEPROM is valid and SLG-20 retractable landing gear is calibrated. This parameter is automatically set to 27 when the attached SLG-20 are calibrated. If this parameter is not 27, the SLG-20 will boot in ERROR mode, parameters will be reset to defaults, and for safety reasons the legs will not actuate. |
| dev\_id     | 1             | Not used                                                                                                                                                                                                                                                                                                                                                                                                                       |
| left\_trim  | 100           | The starting position of the LEFT servo in centidegrees. This parameter is automatically set by the calibration procedure, but can be adjusted manually with care.                                                                                                                                                                                                                                                             |
| right\_trim | 8100          | The starting position of the RIGHT servo in centidegrees. This parameter is automatically set by the calibration procedure but can be adjusted manually with care.                                                                                                                                                                                                                                                             |
| fs\_ms      | 500           | Timeout before loss of input signal will trigger a failsafe in milliseconds                                                                                                                                                                                                                                                                                                                                                    |
| srv\_type   | 0             | Type of servo motor. Set to 0 for the D951-TW, Set to 1 for the HS-7950-TH, Set to 2 for the D951-TW-V2. If unsure, refer to [Servo Types](/slg20-retractable-landing-gear-altax-manual/reference/servo-types.md)                                                                                                                                                                                                              |