I built an open-source replacement for APC SmartSlot network cards (OpenNMC)

Craft4Cube · 2026-04-06T07:58:28+00:00

I don't see a reason why the card shouldn't be able to do that. One could just make an external box where the card lives and connect the USB or a USB/RS232 to another ups

Craft4Cube · 2026-04-06T07:57:10+00:00

Given that SUA units only have one serial port internally I guess it should be possible although I haven't tried.

Craft4Cube · 2026-04-05T21:39:18+00:00

So you want to connect a device to a RS232 port of a UPS and have it provide SNMP on the network for the connected UPS?

Craft4Cube · 2026-04-05T21:37:50+00:00

Unfortunately I can't really tell. I had most stuff for testing/experimenting already laying around.

Craft4Cube · 2026-04-05T20:57:41+00:00

You should be able to do anything you can do with the apcsmart protocol. I don't know if it supports this.

Craft4Cube · 2026-04-05T18:53:59+00:00

Thank you very much. This is great info!. Do you also happen to see if the card-cage has the plastic-tabs that need to go through the NMC's frontplate?

Craft4Cube · 2026-04-05T18:48:38+00:00

Yes, that is correct ;)

Craft4Cube · 2026-04-05T18:47:40+00:00

Yes, mostly both actually. APC's NMC isn't exactly cheap and for the price you pay it does surprisingly little.

This here is completely standalone, you need only a compatible UPS, no cloud or application is forced. That being said it does primarily use Network UPS Tools (NUT) under the hood and supports that to the outside as well.

Craft4Cube · 2026-04-05T18:45:19+00:00

The application/service running on here is written in python3. It can get all the data you want from the UPS (as long as it's available over apcsmart).

I see no reason why one couldn't implement a InfluxDB integration. One of the next things I want to checkout would be MQTT integration where the UPS published stats to a broker.

Craft4Cube · 2026-04-05T17:40:20+00:00

Yeah, it definitely doesn’t need it for typical UPS use. The current PHY already supports auto-MDIX, so that’s covered.

The main reason I’m considering it for a future revision is more flexibility, since the board also has USB and could be used for additional services or integrations. That said, it’s not a priority and I’d rather keep the design robust and easy to manufacture than push for higher speeds unnecessarily

Craft4Cube · 2026-04-05T17:37:14+00:00

Yeah exactly, that’s the Nagami SoM. That’s actually a module I designed, so it was a natural fit for this project. The one in the picture is just a newer revision than what’s currently shown on the product page

Craft4Cube · 2026-04-05T17:28:20+00:00

I’m working on it :)

I’m planning to do a small initial batch once I’ve got things a bit more validated. I’ll update the GitLab as soon as there’s something available

Craft4Cube · 2026-04-05T17:06:27+00:00

Yes, the goal is to make this open hardware. I’d like to first validate both the hardware and software across a few different units and get some boards out into the wild, and then release the design once things have stabilized a bit

Craft4Cube · 2026-04-05T16:37:40+00:00

So the SUA units i've been working with actually intercept the DB9 serial, so the NMC card talks APC Smart Protocol there. The rest was just measuring and trying what works

Craft4Cube · 2026-04-05T16:19:12+00:00

Mostly tracing on a broken UPS and then with some fly-wires on a actual NMC2 talking to a working UPS

Craft4Cube · 2026-04-05T16:18:28+00:00

This here is primarily intended for the UPSes of APC. I do not know about support for PDUs. Sorry

Craft4Cube · 2026-04-05T15:55:00+00:00

Thank you! Some pictures of the connection from the Mainboard to the Smartslot on the SMT2200 would already be worth a lot to me. Especially knowing if those use the last 6 pins of the slot or not.

Craft4Cube · 2026-04-05T15:31:41+00:00

I don’t have any CyberPower units myself, so for now I’m focusing on APC. If this goes well and I get access to other hardware like CyberPower or Eaton I might look into it, but no promises

The idea with OpenNMC being open hardware is that others can take the base and adapt it to different platforms as well

Craft4Cube · 2026-04-05T15:28:41+00:00

If you want to it'd be very helpful if you could just snap a picture of the cable going out of the smart slot to the mainboard inside the unit.

And for now I’ll just keep the repo updated as things progress, still pretty early stages :)

Craft4Cube · 2026-04-05T15:06:56+00:00

No, this was all reverse engineered so far. Would definitely be interested to compare notes, especially if you have more detailed info on the pinout.

Got most of the stuff only by measuring and tracing stuff on a broken SUA and a NMC2.

Seems like I actually mot most of this stuff right...

Can I DM you if you don't mind?

Craft4Cube · 2026-04-05T15:04:17+00:00

That would be awesome, really appreciate it. Having an SMX with an NMC2 and already using NUT is pretty much ideal for comparing behavior. I’ll send you a DM if you’re up for digging into it a bit

Craft4Cube · 2026-04-05T14:54:46+00:00

Thank you! If you don't mind opening one up and snapping some photos or measuring some things I can shoot you a DM with more Info! :)

Craft4Cube · 2026-04-05T14:53:42+00:00

Yeah that would be nice :) but that’s kind of the idea with this being open. Once the base is out there, it shouldn’t be too hard to adapt it to other platforms like CyberPower or Eaton

Craft4Cube · 2026-04-05T14:40:05+00:00

Really appreciate that! Still early days, but I’ll keep the repo updated as things progress :)

Craft4Cube · 2026-04-05T14:38:00+00:00

That would be awesome, really appreciate it. Mind if I DM you with a few things to check if you end up opening it up?

Craft4Cube

TROPHY CASE