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Sentera I/O modules are Modbus RTU compatible

09/01/2024 Yves Vinck

Sentera I/O modules are Modbus RTU compatible. They are of course used in Sentera HVAC solutions, but because they are universal they can also be useful for your project or product. Fire alarm panels, motion detection, door contacts, etc. ... Sometimes your (HVAC) application interacts with external equipment. Sentera offers a full range of converters or I/O modules. They are widely used in industrial and automation applications, but home automation or ventilation solutions for domestic use also make full use of I/O modules. I/O modules are the interface between a controller and external equipment.

Sentera I/O modules are Modbus RTU compatible
Sentera I/O modules are Modbus RTU compatible. They are of course used in Sentera HVAC solutions, but because they are universal they can also be useful for your project or product.

Fire alarm panels, motion detection, door contacts, etc. are examples of external devices with which your (HVAC) application may communicate. Sentera provides a full range of converters or I/O modules. They are widely used in industrial and automation applications, but they are also extensively used in home automation or ventilation solutions. I/O modules are the interface between a controller and external equipment.

A controller can be either a Sentera HVAC controller, equipped with application-specific Solution firmware, or a PLC (a programmable logic controller). They can connect to equipment from other manufacturers using the Sentera I/O modules, as long as they use Modbus RTU communication. 


I/O stands for Input/Output

  • We talk about inputs when we want to be able to process incoming signals from external equipment.
  • We talk about outputs when we want to control or activate external devices. 


Scheme IO modules

Typical examples where we want to be able to read external information via the inputs (I) of our I/O modules are:

  • Temperatures: for many HVAC applications it is important to measure the difference between indoor and outdoor temperatures, or the difference between floor and ceiling temperature, or we need to measure the supply air temperature to determine whether we should activate the heater, etc.
  • Sensors: most HVAC sensors make their measurement information available via an analog signal. The exact measured value can then be derived from the magnitude of this signal. Analog signals are universal and therefore it does not matter who the manufacturer is or what is being measured, if the information is available via an analog signal it can be read by our I/O modules.
  • Digital inputs: these can come from fire alarm control panels, intrusion control panels, passive infrared motion detectors, magnetic (door) contacts, etc. 


Some modules such as the DADCM-44 have inputs to which universal PT500 temperature sensors can be connected directly. In addition, the DADCM-44 has 4 analog inputs. These are able to read 0-10 VDC, 0-20 mA or PWM analogue information that comes from sensors, etc.

Digital input modules such as DDACM can be connected to an output contact of an external device as described above (e.g. fire alarm control panel). In the event of fire, the contact of the fire alarm control panel will close and thus activate the digital input of the DDACM. This is indicated in the corresponding Modbus register of the DDACM. The PLC or HVAC controller reads this information from the Modbus registers and takes action (e.g. switch off or boost ventilation, depending on how this is programmed for a specific application). 


All this incoming information is processed by the PLC or Sentera HVAC controller via simple or complex algorithms. We use the results of these algorithms to control external equipment via the outputs (O) of our I/O modules. Typical examples of this are:


  • Transmitting digital (on/off) signals to fire alarm control panels, air handling units, etc.
  • Positioning an air valve in an air duct
  • Speed control of a fan or air handling unit, etc.
  • Switching On/Off a humidifier, heating element, hot water valve, etc. 


Here you find a complete overview of the Sentera I/O modules.
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