The lasting damage was knowing it could happen at all: that a single contributor with no stated organizational backing could submit compliance infrastructure for surveillance law directly into the software that boots your computer, get it merged by two Microsoft employees, and have the creator of systemd personally block the removal.

The systemd PR was merged by Luca Boccassi, a systemd maintainer who works for Microsoft. Lennart Poettering, the creator of systemd who spent years at Red Hat before joining Microsoft in 2022, had just left Microsoft to found a new startup weeks before the merge, but he has remained active in systemd development.

The most powerful gatekeeper for the init system that boots most Linux machines is employed by a company with significant commercial interest in OS-level identity infrastructure becoming normalized. He let the PR through.

The apcsmart driver should recognize (or at the very least, work with) the majority of Smart-UPS models — which includes Smart-UPS, Matrix-UPS and Back-UPS lineups, among few other ones.

Currently, we can roughly divide APC hardware into four groups (note that the division isn’t strict by any means, and the borders between those are pretty fuzzy):

[very] "old" models

These models usually have old APC logo, white color and no programmable EEPROM; you won’t find them listed anywhere on APC’s site either. The support for those will be usually based on driver’s compatibility tables, or if the model (firmware) is not listed in those — the driver will try to follow the very basic subset of features, while still trying to remain useful. Despite "smart" tagname, they often tend to behave in pretty dumb way (see the section below about shutdown behaviour).
Example models:

    Smart-UPS 2000I

    Smart-UPS 900I

"new" models

These models usually come from late 1990s / pre-2009 times. They are often referred to as "3rd. gen". For the most part, they have programmable EEPROM, report supported commands and capabilities, and should work just fine with the apcsmart driver.

"microlink" models

WARNING: These are not natively supported by apcsmart (or as of this writing by apcupsd, for that matter, if you’re wondering). Around 2007, APC (now APC Schneider) decided to go back to its proprietary roots, and all the new models (SMT, SMX, SURTD) use completely different protocol and cables. If you purchased a new APC UPS — that uses cable with RJ45 on the one end, and DB-9 on the other — then you have such model. Your only option to support it through NUT is to purchase a "legacy communications card" —  part #AP9620 (google AP9620 for more details). Or if that’s not an option, rely on official software.
UPDATE:

Later releases of apcupsd claimed support for new APC protocols, so it is worth checking if apcupsd software would work with your device, and apcupsd-ups NUT driver would handle it as part of NUT-managed ecosystem.

Microsol models

Several Microsol serial models sold in Brazil have been rebranded as APC Back-UPS, and the model numbers tend to start with "BZ". If you have one of these "Nobreaks", they will not work with the apcsmart driver — please see the solis(8) driver instead.
Example models:

    Back-UPS BZ1200-BR

    Back-UPS BZ2200BI-BR

Another thing to remember is that Smart protocol is not USB protocol. If you have UPS with both USB and serial ports, then depending on how you connect it, you will need either apcsmart or usbhid-ups driver.

Generally this driver should work for all the APC Modbus UPS devices. Some devices might expose more than is currently supported, like multiple phases. A general rule of thumb is that APC devices (or firmware versions) released after 2010 are more likely to support Modbus than the USB HID standard.

Tested with the following hardware:

SMT1500 (Smart-UPS 1500, Firmware 9.6)

SMX750 (Smart-UPS X 750, Firmware 10.1)

SMX1500 (Smart-UPS X 1500, Firmware 15.0)

SMX2200 (Smart-UPS X 2200, Firmware 15.0)

Note that you will have to enable Modbus communication. In the front panel of the UPS, go to Advanced Menu mode, under Configuration and enable Modbus.

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