---
title: "ctrlX Data Layer on ctrlX OS"
description: "The LumiScan apps on ctrlX OS (ctrlX CORE or ctrlX IPC) - the ctrlX Data Layer, viewing nodes, the ctrlX PLC, method results, settings files and logs."
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/ctrlx-data-layer.html"
---

# ctrlX Data Layer on ctrlX OS – LumiScan Keryx

> [!NOTE]
> On a PC with Windows 11 or Ubuntu 24.04 the apps use LumiScan Keryx instead: see [LumiScan Keryx on a PC](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/keryx.html).

On ctrlX OS - a ctrlX CORE or a ctrlX IPC - the LumiScan apps are installed from the ctrlX Store and use the **ctrlX Data Layer** of ctrlX OS. There is nothing to install or start for the Data Layer itself.

## Where the nodes are

Every app registers its nodes under `hdvisionsystems/<app>/…`, with the same addresses as on a PC. See [Addresses and Modules](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/addresses.html). Look at them, write them and call methods in the Data Layer view of the ctrlX OS web interface.

## Connecting a PLC {#connecting-a-plc}

A ctrlX PLC program on the same device reads, writes and calls the nodes of the apps directly.

- Use the plain nodes - numbers, booleans, strings and arrays - for PLC logic.
- Results that are FlatBuffers messages need their schema to be decoded. AI Object Matching provides its schema and describes how to import it into ctrlX PLC Engineering in its manual.

## Results of a method call

A method call answers with a ctrlX result: `DL_OK` when it ran, otherwise for example `DL_TOO_MANY_OPERATIONS` or `DL_INVALID_VALUE`. The meaning of each is in [Results of a method call](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/status-codes.html#method-results).

## Settings files

The settings of each app are files in the app’s folder of the active configuration, `/var/snap/rexroth-solutions/common/solutions/activeConfiguration`. Upload them through the ctrlX web interface, or with WebDAV where direct upload is not available. Each app’s manual describes its files under **Uploading Data**. Settings can also be changed on the Data Layer, see [Settings, Modules and Restart](https://docs.hdvisionsystems.com/en/lumiscan-keryx/1.0.0/settings-and-modules.html).

## Logs

An app writes its messages to the ctrlX OS system log. Read them in the Logbook of the ctrlX web interface, or with `journalctl`.

An app without a valid licence stops shortly after it starts; the reason is in the system log. See [LumiScan Licensing](https://docs.hdvisionsystems.com/en/lumiscan-licensing/1.0.4/index.html).