Ok. So you don't have a Pi yet, and you want the results in Home Assistant. And you are monitoring them because you are concerned they fail periodically and you need to be alerted. All good.
To check if the output is open-collector the or not there are two ways. First is to ask the manufacturer, or read the data sheet. I couldn't find a technical data sheet for the pump, but you might have better luck.
The second way would be to attach a multimeter (in DC volt range) to the output (positive) and ground (negative) and look for a voltage while the pump is running. If it's open-collector there won't be one, or it'll float around a bit but mostly stay near zero. To use an open-collector output you add a pull-up resistor to your desired voltage, in this case 2.7k (or greater) to 3.3V. Now, when the internal transistor conducts, it pulls the collector to ground, so you see zero volts. When the transistor does not conduct, the pull-up resistor pulls the output up (in this case to 3.3V) so you see 3.3V. The internal transistor switches once or twice per revolution, so you'll see a pulse train on the output related to the speed of the pump. Clearly if there is no pull-up then you won't see much going on.
In most micros there is an internal pull-up you can turn on, which is often adequate for this kind of application. It's a software function that you include in your program that monitors the GPIO.
I'm being deliberately vague because the answer is always "it depends", and you won't know for sure until you've tried various things. If you find, for example, that your pump signal output is 12V then you'll need an alternative technique.
Getting on to the micro. If you are already running Home Assistant on a Pi then you could hook up these pump signals to the GPIO header and read them directly with software on the Pi, reporting to Home Assistant on the Pi.
This works if the pumps are close to the Pi. You don't want to be running signals over long wires if you can avoid it. If the pumps are some distance away then you can collect the data with one micro and transmit it to another over wifi, or ethernet, or serial. Because the task is very simple you might be better off with a dedicated microcontroller such as a Pi Pico with wifi, for example.
Again, vague answers until all the unknown stuff has been shaken out.
Here's a discussion from some guy wanting to do something similar. He's well down the track, so you can seeit is possible. However he's using different hardware, so assumptions must be tested before you can be confident they apply to your situation:
https://community.home-assistant.io/t/i ... tes/850110
Here's another one, slightly lower level, but touching on the kinds of issues you might encounter:
https://community.home-assistant.io/t/4 ... fan/647505
To check if the output is open-collector the or not there are two ways. First is to ask the manufacturer, or read the data sheet. I couldn't find a technical data sheet for the pump, but you might have better luck.
The second way would be to attach a multimeter (in DC volt range) to the output (positive) and ground (negative) and look for a voltage while the pump is running. If it's open-collector there won't be one, or it'll float around a bit but mostly stay near zero. To use an open-collector output you add a pull-up resistor to your desired voltage, in this case 2.7k (or greater) to 3.3V. Now, when the internal transistor conducts, it pulls the collector to ground, so you see zero volts. When the transistor does not conduct, the pull-up resistor pulls the output up (in this case to 3.3V) so you see 3.3V. The internal transistor switches once or twice per revolution, so you'll see a pulse train on the output related to the speed of the pump. Clearly if there is no pull-up then you won't see much going on.
In most micros there is an internal pull-up you can turn on, which is often adequate for this kind of application. It's a software function that you include in your program that monitors the GPIO.
I'm being deliberately vague because the answer is always "it depends", and you won't know for sure until you've tried various things. If you find, for example, that your pump signal output is 12V then you'll need an alternative technique.
Getting on to the micro. If you are already running Home Assistant on a Pi then you could hook up these pump signals to the GPIO header and read them directly with software on the Pi, reporting to Home Assistant on the Pi.
This works if the pumps are close to the Pi. You don't want to be running signals over long wires if you can avoid it. If the pumps are some distance away then you can collect the data with one micro and transmit it to another over wifi, or ethernet, or serial. Because the task is very simple you might be better off with a dedicated microcontroller such as a Pi Pico with wifi, for example.
Again, vague answers until all the unknown stuff has been shaken out.
Here's a discussion from some guy wanting to do something similar. He's well down the track, so you can seeit is possible. However he's using different hardware, so assumptions must be tested before you can be confident they apply to your situation:
https://community.home-assistant.io/t/i ... tes/850110
Here's another one, slightly lower level, but touching on the kinds of issues you might encounter:
https://community.home-assistant.io/t/4 ... fan/647505
Statistics: Posted by ame — Sat Nov 22, 2025 11:45 pm