Looking for an UPS unit >=600Watt with RS232 and documented protocol

[DiTBho]

I am looking for a UPS unit

• >=600Watt
• RS232 (I cannot use USB)
• documented serial protocol

I know some units are listed at networkupstools, but it's quite confusing about which unit has an RS232 documented protocol 

[BradC]

Old 3rd or 4th generation APC SmartUPS (SU or SUA)

[DiTBho]

What about Atlantis's UPS? I see some have both RS232 and USB 

[DiTBho]

About UPS units made by APC, this page looks interesting 

[Nominal Animal]

RS232 (I cannot use USB)

If you cannot find one with RS232, but do find one that has USB but has a documented Linux/open source-supported protocol, you can use a microcontroller with USB host, and an RS232 driver (MAX232 or similar) or an UART isolator and level shifter like TI ISO6721 (if your computer/SBC has UARTs instead of RS-232-level ports).  I myself would use a Teensy 4, of course, but that's just because it is the microcontroller I know and have that fits the use case.

I suppose ESP32-S2 would be among the cheapest easily available alternatives, 7 or 8€ at Olimex, considering its UART and USB Host support. I do not have one, though, so I cannot say if it is a practical option for that.

apcupsd-3.14.14 (latest from 2016) seems to use USB HID (0x84, Power Page); see HID Usage Tables 1.4 (PDF), page 357: 30 Power Page (0x84).  This is closest to a standard I know of.

This means that interfacing to an USB HID Power Page / UPS using a small microcontroller with USB Host port should be simple – comparable to say a force-feedback gamepad or joystick –, but forwarding the same connecting to e.g. apcupsd via UART isn't trivial: you'd need to either write your own apcupsd drivers, or have the microcontroller emulate an older APC UPS.

Instead, I would recommend you use a microcontroller that handles the monitoring, with just a simple text-based serial interface to your computer or SBC, with basically all the monitoring logic in the microcontroller.  Remember that the serial connection is full duplex, so design the protocol such that the microcontroller can send events to the SBC/computer even without the computer prompting for it first, i.e. NOT a synchronous-query-response one.
(Personally, I'd have each query and response start with an identifier, with UPS events having a separate space from queries/responses.)

[DiTBho]

aren't there UPS without anything but digital lines signaling status and events?

like,

• digital line: the battery is ok
• digital line: lost power, system on battery

I am more interested in converting 12V to 230V AC.
I can build the rest of the circuits myself.

[Jeroen3]

About UPS units made by APC, this page looks interesting 

"Sprinkle a few calls to usleep() in your code and everything will work a lot better." 

But to be honest, you're looking for a product in the wrong century I'm afraid. Have you tried specialty purposes, such as mil or railway?
Most IT UPS's today are network or usb managed. The usb protocol is a standard device class. It should be trivial for a PI -zero to convert this.

Or you get into specialty units, with module cards: https://www.apc.com/uk/en/product/AP9613/apc-dry-contact-i-o-smartslot-card/

[Ed.Kloonk]

aren't there UPS without anything but digital lines signaling status and events?

like,

• digital line: the battery is ok
• digital line: lost power, system on battery

I am more interested in converting 12V to 230V AC.
I can build the rest of the circuits myself.

This is where I'm at. Everything modular. Plenty of redundancy.

[DiTBho]

you're looking for a product in the wrong century I'm afraid

well, I specifically bought my first DSO with an RS232 option card to avoid dealing with USB.
While my second DSO has an ethernet option.

for me, Ethernet would be ok in UPSs, but only if
- uses IP-static
- uses UDP/IP (better) or TCP/IP protocol


* * *

I've already designed, made, and tested a circuit that detects power loss, distinguishes it from noisy spikes, and reports "bad quality power line" to the host.

I can even build my own mini UPS unit, DC-12V in parallel to its PSU, to safely shut down my micro NAS. Less than 60 watts, less than 15 minutes to sync disks, remount them RO, and shutdown.

It works fine, but commercial UPSs are better
1) can also filter the power line, avoiding to propagate spikes
2) 600Watt can allow the server to safely shutdown, protecting everything instead of only the NAS

[Jeroen3]

I don't know but it sound like you're making life difficult for no reason. I just hooked up a BX750MI via USB to my Synology. Plug&Play.  I can even share the UPS with the other nas over internet.

Via ethernet most of them use SNMP. And if they are static ip or dhcp is up to the config you put in.

Maybe, for your level of DIY an 24V industrial UPS is more suitable? Like Meanwell DR-UPS or APC BVS480XDPDR?

[Nominal Animal]

aren't there UPS without anything but digital lines signaling status and events?

The USB HID Power is the closest thing to that, really.

For example, Eaton Ellipse PRO 650 costs 234 € here, and is supported by Network UPS Tools using the usbhid-ups driver, so it definitely uses the USB HID Power class.  (See here.)

The cheapest USB hereabouts seems to be APC Back-UPS BE650G2-GR for 150€.  Getting the needed RJ45-USB cable may be annoying, and even then it is not clear what protocol it uses, and whether apcupsd supports it.  PowerChute Business Edition for Linux installs USB HID device symlink, and manual tells Mac users to use the system shutdown features, so I do believe – but cannot confirm! – that it (and BE850G2-GR too) uses USB HID Power class.
 _ _ _ _

While USB can be horribly annoying, when you have a (reliable: ignore Broadcom) hardware USB host or host/device implementation, HID is nice.
Heck, LUFA has USB generic HID host support for AT90USB647 and AT90USB1287, 8-bit AVRs.

[DiTBho]

no, I don't want to deal with USB.

[DiTBho]

I don't know but it sound like you're making life difficult for no reason.

I have my reasons 

SNMP. And if they are static ip or dhcp is up to the config you put in.

That's interesting. Thanks!
Even if SNMP is ... something I don't like.

Maybe, for your level of DIY an 24V industrial UPS is more suitable? Like Meanwell DR-UPS or APC BVS480XDPDR?

My micro NAS is a custom cluster of three PowerPC SBCs, with a custom PSU which integrates a custom "micro UPS-like". Everything works with 12V DC, disks and SBCs are all 12V DC powered, and we are talking about less than 5A. A piece of cake to be designed and built.

The Strong Power UPS is much much more difficult and it requires much more skills, which frankly ... I've never put into practice; it's for the server, which has a 230V AC PSU, and it also has to filter the incoming power line for the whole setup (server + micro NAS), protecting it from glitches and noises.


Yes, we have redundancy on the NAS
- protected by its integrated micro UPS
- protected by the external Strong Power UPS

[BradC]

aren't there UPS without anything but digital lines signaling status and events?

A 3rd or 4th generation APC SmartUPS (SU or SUA) in "dumb mode" will do exactly that.

[langwadt]

https://kirbah.github.io/apc-ups/Smart-protocol/ ?

[BradC]

http://www.apcupsd.org/manual/manual.html#simple-custom-voltage-signalling-cable-for-dumb-upses