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Joined: Mon Feb 04, 2013 10:22 pm

Controlling 5 Belimo damper actuators from an RPi

Mon May 14, 2018 10:03 am

I'm renovating my home, and as a neat side project I've bought 5 Belimo damper actuators to control the airflow inside. The way these actuators work is that they a line in that accepts a 0 - 10 voltage which represents a 0 - 100 % rotation of the servo, which corresponds to an open or closed position of the damper. They also have a line out that they set a voltage of 0 - 10V on which corresponds to the actual position of the servo.

So my mission is to somehow send 5 channels of 0 to 10V over these lines, and if at all possible, also read back the output lines for some nice feedback on what the dampers are doing. I've been informed that PWM would be fine to send it out. I'd then build a nice web interface that I could access inside the home to control the air.

Does anyone know of a PiHAT that offers channels like this? Maybe 5 in one go, or maybe stackable to get 5? Alternatively, I'd also be fine with an Arduino style or similar embedded board that has these features which I could program and connect to the RPi.

If at all possible I'd like to avoid designing some circuitry. I am capable of soldering and have built small projects like restoring audio equipment and building a gainclone amp, but since this setup will be part of my house, I'd like it to be built of replaceable parts as much as possible, in case I'd ever sell it or something.

Thanks for your tips and ideas!

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Re: Controlling 5 Belimo damper actuators from an RPi

Mon May 14, 2018 9:00 pm

Ok interesting project.

First if you need a range 0 -10v output then this is an analog output. Digital is either 0v or 10v with nothing in between. So this means you will need a DAC (digital to analog conveter). You will need to create a digital PMW signal with a duty of between 0 - 100% then the DAC will convert the % of duty cycle to an analog voltage. The range of output of this analog voltage will be in the range of the PWM voltage witch is below the 0-10v that you want so then you will need an amplifier to bring it up to the needed 0 - 10v.

Reading the ouput is a bit easier but is basically the same process in reverse. You will need an ADC (analog to digital converter). You will have to use a voltage divider to bring the voltage down from 0-10v to 0-3.3v or less then then read this voltgae through an ADC.

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