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The advantages of a potentiometer with Modbus RTU

21/09/2022 Yves Vinck

Potentiometers with minimum and maximum limit, working from low to high speed or vice versa, with 0-10 volts, 0-20 mA or PWM output, infinitely adjustable or with adjustable steps (…) were already part of our assortment. Today we have expanded our potentiometer family with the SDP-M010 series that are equipped with Modbus RTU. As a result, not only are the settings available via the Modbus registers, but from SenteraWeb or your Building Management System you can also read the position of the potentiometer and even overwrite the output.

The advantages of a potentiometer with Modbus RTU
Manual control
We mainly know a potentiometer as a device with which we can directly control the speed of an EC fan via a rotary knob or the speed of an AC fan via a speed controller. This unit, which in itself is a very simple device and is built into almost every ventilation application, had limited possibilities until we developed this version with Modbus.

Apart from demand-based ventilation, where sensors or a network of sensors determine how much ventilation is needed, manually controlled ventilation remains also very popular. A choice should be made between a very simple manual control with a potentiometer, or a fully automatic control based on sensors, where manual intervention is difficult, usually even impossible. However, thanks to the development of this Modbus RTU potentiometer, numerous new combinations and possibilities are available.

Potentiometer with Modbus RTU communication
Whether it concerns small installations where one potentiometer controls one fan or valve, or a large installation with several rooms where also sensors are used, this new potentiometer can prove its worth.  Use your creativity to create new solutions. These are some ideas: 

  • Applications where you will manually control fan speed but where, thanks to the presence of Modbus RTU, you can overrule the potentiometer remotely. Think of automatic switch-off outside working hours or during holiday periods, or free cooling during summer nights. You can take control via SenteraWeb but also via any building management system that is Modbus RTU compatible.
  • Applications where we will combine demand-based ventilation with manual control. Think of meeting rooms or classrooms where, for example, it becomes possible to additionally “clean” the room during breaks. After the measured value of the sensor has fallen back below the desired value, the automatic control - based on the measurements of the sensor – will take over again. So efficient ventilation without unnecessary energy loss.
Sentera's Modbus RTU potentiometers offer many additional options. They can all be set via the Modbus registers:
  • Direction of rotation from minimum to maximum or from maximum to minimum
  • Adjustable minimum and maximum output value
  • Output signal type selectable from 0-10 VDC, 0-20 mA, 0-100% PWM
  • Modbus communication timeout
  • Read out the potentiometer output
  • Overwrite the output via Modbus RTU
The SDP-M010 is available in 3 versions:
  • The SDP-M010-AT with zero position when completely turned anticlockwise
  • The SDP-M010-BT has no zero position and thus will not have an output lower than the minimum value set via Modbus
  • The SDP-M010-DC has a dry contact output when completely turned anticlockwise that allows external equipment to be turned on or off
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