> 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/downloads/en/codesys-hvac-downloads/hvac-modbus-i-o2-library.md).

# HVAC ModbusIO2 Library

### Documentation

> You can find all important information about this library, including the license and full documentation, in the documentation section.

<a href="/spaces/6G4WDUYxjH3a0to8hJov/pages/3c000c2e1c5802f3cddb686a7f2386cfb40367a5" class="button secondary" data-icon="books">To the documentation</a>

### Current version

<details>

<summary>1.0.3.3 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-HVACModbusIO2-1.0.3.3.compiled-library-v3" class="button primary" data-icon="arrow-down-to-line">Download</a></summary>

Release Date 18.05.2026

**Improvement**

* Affected modules - 8AO

***

*Technical details and security for download*

<table data-header-hidden><thead><tr><th width="292.62353515625"></th><th></th></tr></thead><tbody><tr><td><i class="fa-file-contract">:file-contract:</i> SBOM (Software Bill of Materials)</td><td><a href="https://dl.powerio.com/downloads/HVACModbusIO2-Library-1.0.3.3-466cdf60d02a.spdx.json">Link to the SBOM (spdx)</a></td></tr><tr><td><i class="fa-certificate">:certificate:</i> Signing</td><td>Yes (more info)</td></tr><tr><td><i class="fa-abacus">:abacus:</i> Signed library hash</td><td><code>466cdf60d02a</code></td></tr></tbody></table>

</details>

***

### Older versions

<details>

<summary>1.0.2.8 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.6.compiled-library">Download</a></summary>

Release Date 14.11.2024

**Improvement**

* Affected modules - All output modules:

  **Previously:**

  * During initialization, values were read in first
  * The SafeState was reset in the process

  **New with `xUseSafeStateBeforeInit`:**

  * FIRST the SafeState is set as output
  * THEN the values are read in

</details>

<details>

<summary>1.0.2.6 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.6.compiled-library">Download</a></summary>

Release Date 08.05.2024

**Bug fixes**

* ***H1\_8AO:*** Bug fix when setting output value(s) during initialization
* ***H1\_8DO:*** Bug fix when setting output value(s) during initialization

</details>

<details>

<summary>1.0.2.5 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.5.compiled-library">Download</a></summary>

Release Date 22.11.2023

**Bug fixes**

* ***H1\_8AO:*** Bug fix when setting output value(s)

</details>

<details>

<summary>1.0.2.4 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.4.compiled-library">Download</a></summary>

Release Date 25.10.2023

**Bug fixes**

* ***H1\_8AI:*** 8AI query improvement

</details>

<details>

<summary>1.0.2.3 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.3.compiled-library">Download</a></summary>

Release Date 18.10.2023

**New features and changes**

* none

**Bug fixes**

* ***H1\_8AI:*** Erratic behavior when updating analog inputs. It happened that an input that actually had 0V showed 1V. The query for the "last change" was faulty and was corrected in this version.

</details>

<details>

<summary>1.0.2.2 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.2.2.compiled-library">Download</a></summary>

Release Date 04.09.2023

**New features and changes**

* Update of the dependency library from *ModbusFB* `4.2.0.0` to `4.3.0.0`

**Bug fixes**

* ***H1\_8AO:*** When using analog outputs, the value was not transmitted when changing *TwoPointFunction* (converter) parameters. This has now been fixed and the values are now transmitted directly accordingly, without having to rewrite the outputs.
* ***H1\_8DO/H1\_8DOR and H1\_4DIOR:*** Digital outputs are now written directly, even if the output is only active for one cycle. Previously, state changes were not taken into account and it could happen that an output was not written. It is strongly recommended to use this version or a newer version.

</details>

<details>

<summary>1.0.1.4 - HVACModbusIO2 - <a href="https://dl.powerio.com/downloads/powerIO-CODESYS-3.5.17.2-HVACModbusIO2-1.0.1.4.compiled-library">Download</a></summary>

Release Date 08.02.2023

**New features and changes**

* n.a.

</details>

### Details


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