Would a DIN-rail Ethernet wired input module be useful for Home Assistant?

Hardware
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1

Hi everyone,

I’m evaluating a possible hardware project and I'd like some honest feedback before spending time on the design.

The idea is a small DIN-rail Ethernet input module for Home Assistant / MQTT / Modbus TCP, mainly for bringing wired signals into HA without Wi-Fi, batteries, cloud services, or custom PC software.

Possible use cases:

  • existing wired alarm contacts;
  • door/window contacts already wired to a panel;
  • wired push buttons;
  • gate/garage door contacts;
  • float switches / level sensors;
  • S0 or pulse outputs from meters;
  • generic dry contacts from machinery or technical-room equipment.

The first version I'm considering would be something like:

  • 16 opto-isolated digital inputs;
  • Ethernet, possibly PoE;
  • 12–24 V DC supply;
  • local web configuration;
  • MQTT with Home Assistant discovery;
  • Modbus TCP;
  • per-input debounce/filtering;
  • pulse counter mode;
  • possibly alarm EOL/DEOL resistor supervision;
  • no Wi-Fi, no Bluetooth, no cloud.

I'm trying to understand whether this would solve a real problem, or whether most people would just use ESPHome, KinCony, Shelly, a PLC, or cheap Modbus I/O modules.

A few questions:

  1. Would you personally use something like this?
  2. What would be the main use case for you?
  3. Is 16 inputs enough, or would 24/32 be more useful?
  4. Is PoE important, or is 12–24 V DC enough?
  5. Would alarm-style EOL/DEOL supervision matter?
  6. Would you prefer MQTT discovery, Modbus TCP, ESPHome compatibility, or something else?
  7. What price range would feel reasonable for a finished DIN-rail product with enclosure and documentation?

I'm not trying to advertise anything here. I'm still at the validation stage and would rather find out now if this is actually useful, already solved, or too niche.

Thanks for any brutally honest feedback.

2

There is this:

and then this:

You would need to make something for that product line that sits in a competitive price range.

3

You’re right, after looking better at the KinCony lineup, the KC868-AI in particular is already very close to the generic idea I had in mind: DIN rail, 48 opto-isolated inputs, Ethernet/LAN, MQTT/ESPHome/Home Assistant support, etc.

So maybe a generic “wired input module for HA” is already too well covered.

The only remaining question is whether there is a more specific gap around alarm/contact retrofits, for example:

  • EOL/DEOL resistor supervision;
  • tamper / cut-wire / short detection;
  • 12 V AUX supply for PIRs and alarm sensors;
  • Ethernet or PoE only;
  • no Wi-Fi/Bluetooth/Tuya/cloud;
  • local web configuration;
  • MQTT discovery without ESPHome/YAML;
  • EU-style documentation and support.

Do you think that distinction would matter, or would you still just use something like the KinCony AI?

4

For that, the Konnected boards (or one of the clones) would be more suitable. No Din rail, but you can keep your existing alarm panel for insurance purposes if you don't want to build from scratch.

5

Thanks for the replies.

After thinking about it more, I’m not sure this is worth pursuing, at least not as a new product.

There seem to be enough existing options already — ESPHome devices, KinCony/Shelly-style modules, PLCs, generic Modbus I/O, etc. — that I’d need a very clear advantage to make another one worthwhile.

So for now I’ll probably leave the idea on hold. The feedback was helpful, and I appreciate it.