HVAC I/O Modbus Modules

The library allows the use of HVAC Modbus I/O modules of the manufacturer powerIO via a RS485 COM port. The devices are appended in the project tree and are parameterized from there without further programming effort. In the I/O Mapping area the assignments of the input/output variables can be set. The modules are available with emergency manual operation level and without. The status of the manual override is queried.

Current version
Article number

Product Description

This library allows you to use the HVAC I/O Modbus Modules 16DI, 8DO, 8DO-R, 4DO-R, 8AI and 8AO. It requires a RS485 COM-Port interface and also a Modbus license (mostly included).

The devices can be added to the device tree and also be extended with various romod modules. Variables can be mapped to the program under the I/O-Mapping Tab.

All output modules are local override/indication devices, the state can be monitored and changed. If the device is local overrided/indicated, then it will be shown under the device tree.

There is also a parameter settings window for each module. Different settings as slave-address, Bus-Timeout, send command or cycle request time can be configured under this section. Many specific I/O extended settings are also available for example: Negation, two-point-function, limiter, damped function etc. The analog input module allows you to select sensors as PT1000/100, Ni 1000, NTC 10k, etc.

The HVAC-Master device is required for configuring the physical hardware COM-Port. Common serial settings can be configured there. The Hardware modules can be decentral installed (for example in electrical distribution boards). Supported bus cable length for the devices is up to 3937 feet (based on the environmental conditions). Each device address is configurable with dip switches. Serial communication settings as baudrate don’t need to be configured, because the devices are supporting “Autobauding”. This feature is decreasing the fault-rate and also the installation time out of the field.

More Informations: www.hvac-automation.com Onlineshop: shop.powerio.com


Programming System

CODESYS Development System V3.5.10.0

Target System

CODESYS Control V3.5.10.0

Supported Platforms / Devices

Tested devices: CODESYS Control Win V3, Raspberry Pi Notice: Use the project ‘Device Reader’ to find out the supported features of your device. ‘Device Reader’ is available for free in the CODESYS Store.

Additional Requirements

RS485 COM port (also possible via USB COM port adapter), Modbus RTU license must be available on the target device.


The I/O connection has no real-time properties. Maximum 30 Romod Slaves per Romod Master Device.


License activation optionally on CODESYS Key or CODESYS Soft Key (free part of CODESYS Controls)(without license 30 min Demo) Licensing per Runtime (SPS) necessary!

Required Accessory

Romod I/O modules from the manufacturer Romutec (www.romutec.de).


powerIO GmbH

Eberhardstr. 65
70173 Stuttgart



This product includes technical support from the original software vendor. To submit your request, please contact the vendor directly.


powerIO GmbH

Eberhardstr. 65
70173 Stuttgart



Additional Downloads


Version History

Version Release Notes Release date
  • free, additional modules, improved configuration

  • Fixed a critical bug, which disconnected some modules on specific I/O behaviour.
  • Some huge speed performance increasements for the full driver.
  • Added delay option for the error flag.
  • The bus doesn't stop now if one module is missing. It just waits until the configurable timeout has reached.