> 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/codesys-hvac/en/hvac-bacnet2-library/beispiele/bacnet-einrichtung-in-codesys.md).
# BACnet setup in CODESYS
In order for the BACnet library to be used, the BACnet IP datalink and the BACnet Server must first be set up in CODESYS.
## BACnet IP datalink
{% stepper %}
{% step %}
**Add Ethernet interface**
In the device tree, the device *Ethernet* is attached. This defines the physical interface for BACnet communication.
{% endstep %}
{% step %}
**Configure Ethernet interface**
Now the device is configured; the IP address of the target device (i.e. your own CPU) must be specified. The IP address of the other BACnet participant is determined communicatively (*Who-Is* – query via broadcast telegram X.255).
{% endstep %}
{% step %}
**Add BACnet IP datalink**
In the device tree, below the device *Ethernet* the device *BACnet IP datalink* is attached.
{% endstep %}
{% step %}
**Configure BACnet IP datalink**
It primarily defines the BACnet network number and the UDP port used (default: 47808).
{% endstep %}
{% endstepper %}
## BACnet Server
{% stepper %}
{% step %}
**Add BACnet Server**
In the device tree, the device *BACnet Server* is attached. It serves as the BACnet communication center and must always be present. The client-server principle is used. The client reads/writes data that the server provides.
{% endstep %}
{% step %}
**Configure BACnet Server**
The target device (our CPU) can be operated both as a BACnet Server and as a BACnet Client (even simultaneously).\
When operating as a BACnet Server, the objects (e.g. a temperature actual value of the target device) are attached as devices below the BACnet Server. When operating as a BACnet Client, the objects are defined in CFC.\
\
It defines the character set used (UTF8) and the option *AutoStart* (automatic start of BACnet communication) is defined
Furthermore, the properties of the object *Device* (i.e. of your own BACnet Server) can be set, which can then be read by another BACnet participant.
{% endstep %}
{% endstepper %}
---
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