> For the complete documentation index, see [llms.txt](https://docs.videc.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.videc.de/acron-9.3/en/anlagenkonfiguration/verfahrensgroessen/extvg.md).

# External process variable

External process variables are references to [process variables](/acron-9.3/en/anlagenkonfiguration/verfahrensgroessen.md) of other plants.\
By way of those external process variables it is possible to access the data of the other plants.

[Connecting objects](/acron-9.3/en/anlagenkonfiguration/verbindungen.md) are required in order to include process variables from other plants as external process variables.

Using the [TCP/IP address](/acron-9.3/en/anlagenkonfiguration/verbindungen/verbindung.md#serveradresse) and [port](/acron-9.3/en/anlagenkonfiguration/verbindungen/verbindung.md#serverport), they connect between the active plant and the plant on which data are to be accessed via the external process variables.

To provide process variables from other plants, the "External connections" allocation option must be enabled.

Access to the data the other plant is only possible with an [active connection](/acron-9.3/en/anlagenkonfiguration/verbindungen/verbindung.md).

If the connection is inactive, no values for those external process variables can be outputted in reports and diagrams.

The [icon](/acron-9.3/en/anlagenkonfiguration/verbindungen.md#symbole) of the external process variable indicates the connection status.

If the "External connections" allocation option is disabled for a process variable, the process variable is deleted, or the plant is removed from Plant Management, the associated external process variable is highlighted and a warning message is displayed.

It is only possible to update the status of external variables with an active connection. If the connections of two plants are inactive and the allocation option of a referenced process variable is disabled, this has no effect on the external process variable. But as soon as the connection is activated, the status of the external process variable also changes, meaning it is highlighted and the warning message is displayed.

<details>

<summary></summary>

Primary interval in the active plant = 1 h

Operating data (Reporter module) for the Primary interval compression level are only displayed for external process variables if there is any interval of 1 h in the allocating plant.

</details>

Note

The marking +++ indicates that the referenced process variable is no longer available.

To ensure access to process variables of a plant from ACRON version 7.3 as from SP7, the 'DataCollect / Connections' option must be activated there in the Designer in the 'Process variables' dialog on the 'Allocation' tab (Comment process variables are not available for connections).

For this plant, in Plant Management on the 'Plant' tab

* access must be provided via TCP/IP by server service.
* the associated port must be entered - this port is used for connecting in plant versions 8.2 and higher.
* the server service must be installed and running.

If changes to the [calculated components](/acron-9.3/en/anlagenkonfiguration/verfahrensgroessen/extvg/register_bereitstellung.md#berechnungskomponenten) and [allocation](/acron-9.3/en/anlagenkonfiguration/verfahrensgroessen/extvg/register_bereitstellung.md#bereitstellung) of process variables are saved in an allocating plant, the changes are displayed in the Multiserver plant via an active Save button, and must also be applied to it.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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://docs.videc.de/acron-9.3/en/anlagenkonfiguration/verfahrensgroessen/extvg.md?ask=<question>
```

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.