---
title: "Settings, Modules and Restart"
description: "The system node of the LumiScan apps - settings files on the Data Layer, creating and removing modules, saving module inputs, restart, and what is kept across a restart."
product: "LumiScan Keryx"
component: "lumiscan-keryx"
version: "1.0.0"
display_version: "1.0.0.7"
latest_version: true
language: "en"
url: "https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/settings-and-modules.html"
---

# Settings, Modules and Restart – LumiScan Keryx

Everything that is not about one module is under `hdvisionsystems/<app>/system/`. The apps come in two families that handle their modules differently. The code readers have only `system/meta/subscription-schema` there (see [Streams](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/streams.html#consumer)).

## Cam Driver, AI Object Matching, Calibration: settings files {#settings-file-apps}

Their modules are the module files that the application settings file lists.

| Node | Kind | What it does |
| --- | --- | --- |
| `system/settings` | string, read and write | All loaded settings as one JSON document: the application file, with each listed module file inlined (passwords shown as `*`). Writing it saves the changed files - each checked by the app first, the old one kept as `.bak` - and marks a restart as required |
| `system/restart-required` | bool, read-only | `true` after a saved change, until the app restarts. Meanwhile every module reports status `-5` (`restartRequired`), and its methods answer `ResourceUnavailable` (ctrlX `DL_RESOURCE_UNAVAILABLE`) |
| `system/control/restart/execute` | method | stops the app and starts it again. The app’s nodes disappear until it is up: wait until `system/restart-required` can be read again |
| `system/control/create-module/execute` | method, inputs `control/create-module/input/module-id` and `content` | writes `<module-id>.json`. Refused when the file exists |
| `system/control/activate-module/execute`, `system/control/deactivate-module/execute` | method, input `control/<function>/input/module-id` | adds the file to, or removes it from, the application file’s list. The file stays. Needs a restart |
| `system/found-modules`, `system/status-text` | read-only | the modules served; why none are |

The Cam Driver adds camera discovery: `system/found-camera-modules`, `found-camera-serials`, `found-camera-mac-addresses`, `found-camera-ip-addresses`, and the `system/force-ip/` handshake. AI Object Matching serves one module at most: `activate-module` refuses a second.

Example - add the camera module `camera2` to the Cam Driver:

1. Write the module’s JSON to `hdvisionsystems/lumiscan-cam-driver/system/control/create-module/input/content` and `camera2` to `control/create-module/input/module-id`, then call `control/create-module/execute`.
2. Write `camera2` to `control/activate-module/input/module-id`, then call `control/activate-module/execute`.
3. Call `hdvisionsystems/lumiscan-cam-driver/system/control/restart/execute`.

A module file can also be changed on disk. AI Object Matching and Calibration read their module file again on `reset`; otherwise a change applies at the next start.

## Template Finder, Object Finder, Area Detector, Text Reader: modules at run time {#registry-apps}

Their modules are made and removed while the app runs.

| Node | Kind | What it does |
| --- | --- | --- |
| `system/modules` | string[], read-only | the modules now |
| `system/create-module/execute` | method, input `input/module-id` | a new module with default inputs, at once. Gone after a restart unless saved |
| `system/remove-module/execute` | method, input `input/module-id` | removes the module |
| `system/save-current-modules/execute` | method | writes the module list into the application file, and deletes the input files of modules no longer in it |
| `system/save-module-inputs/execute` | method, input `input/module-id` | writes the module’s inputs to `<module-id>.json`, restored at the next start |

Each finder adds its own functions, for example Template Finder `system/create-template` and `system/set-template-dir`, Text Reader `system/set-tessdata-dir` and `system/refresh-languages`. See the app’s manual.

Note that `create-module` means two different things: in the settings-file apps a file applied at the next restart, in the finders a live module lost at the next restart unless saved.

## What is kept across a restart {#kept}

| What | Kept |
| --- | --- |
| A finder module’s inputs | when saved with `system/save-module-inputs/execute`; restored at start |
| A finder app’s module list | when saved with `system/save-current-modules/execute` |
| Settings of the Cam Driver, AI Object Matching and Calibration written to `system/settings` | yes, applied at the next start |
| Folders chosen at run time (template, object and tessdata folders) | yes, saved automatically in the application file |
| A consumer’s stream | yes, see [Streams](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/streams.html#saved) |
| The Cam Driver’s stream and the camera connection | **no**: start them again after every start |
| Values written to `input/` of the Cam Driver, AI Object Matching and Calibration | **no**: write them again |

There is no load method: nothing reads a saved file again without a restart, except the `reset` of AI Object Matching and Calibration.