> For the complete documentation index, see [llms.txt](https://support.powerio.com/hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.powerio.com/hub/blog/en/news-blog/verwendung-von-seriellen-schnittstellen-in-user-applications.md).

# Using serial interfaces in user applications

## Description

With the current [firmware version (v4.0 or higher)](/hub/downloads/en/powerio-downloads/t1.b100-firmware.md) for the [powerIO-Box T1.B100](/hub/en/t1.b100/description.md) an important extension is being introduced that enables the direct use of serial ports in installed applications. In particular, this [CODESYS as an application](/hub/en/applications/available-apps/codesys.md) is brought into focus, while other user applications, such as the [HVAC Cloud Adapter](/hub/en/applications/available-apps/hvac-cloud-adapter.md), are also supported.

## **Functionality in detail**

The new firmware makes it possible to assign serial interfaces directly to an application. This means that the communication parameters – such as baud rate, parity and stop bits – no longer need to be configured separately in the web interface, but can be set directly within the respective application.

* Users who use CODESYS are thereby enabled to natively integrate the serial port assigned to the application, so that protocols like BACnet can be used, for example, without additional hardware or software adjustments.
* In addition to CODESYS, other applications can also benefit from this feature. For the Cloud Adapter, which is also available as a user application for the powerIO-Box T1.B100, protocols such as MBus and BACnet can now be used directly.
* All four serial ports can be used. Additionally, the use of port 5 is also possible with a [serial port expansion card (Port 5)](https://www.powerio.com/de/produkte/t1.c100-xxx) possible.

<figure><img src="/files/1bd5db6eb2202bdaac1b4285466c77d280ed9342" alt=""><figcaption><p>Assign serial port to the application</p></figcaption></figure>

<figure><img src="/files/8a774e28d9ed9ef3b0926141dd41929e65065c68" alt=""><figcaption><p>Assignment of serial port 5, when using an expansion card</p></figcaption></figure>

Further information and detailed instructions can be found in the [manual](/hub/en/t1.b100/feldbus-protokolle/application.md) .


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