[Nut-upsuser] OT: gadget to display time remaining

Jon Bendtsen jbendtsen at laerdal.dk
Tue Nov 30 10:33:46 UTC 2010

On 28/11/2010, at 03.36, James wrote:

> On 11/22/10 05:42, Jon Bendtsen wrote:
>> On 22/11/2010, at 02.26, James wrote:
>>> I have two UPSs, one is not connected to a computer.
>>> I am looking for a gadget that I can plug in to the other one so I can
>>> see the time remaining without a computer.
>> That would be network UPS tools, get it from http://www.networkupstools.org/ ;-)
>> Oh, and be sure to get the right UPS, because not all UPSes show the information.
>> I have a guru plug server plus connected to the Microdowell BP500 UPS in the attachment, the UPS showing no Battery runtime. The other UPS is a APC Smart-UPS 1500 and in my old debian sta(b)le installation running Network UPS Tools upsstats 2.0.4 there was no information about battery runtime, but see the attachment.
>> JonB
> Without a computer. :-)

The guru plug is almost not a computer, but rather an appliance.

Some UPSes has a network port to tell this information, but basically it is just a build in computer.

Personally I dream of this standard:

Primary goals:
	UPS(s) and Server(s) automatically talk together with no need for configuration using just 1 cable, the power cable, without the need for new special power cables
	UPS(s) can start Server(s) in some (on server) configurable order such that the upstart do not pull too much power
	Server(s) with X power supplies connected to Y different UPS(s) will automatically know the state of all UPS(s) using just the power cable without spilling information over from one failed UPS connected to 1 or more power supplies to all the other UPS(s) connected to another power supply in the same server.

Secondary goals:
	Server(s) can tell the UPS how much load they would likely draw as a maximum
	UPS(s) can stop powering on servers if the load is too high
	Server(s) can refuse to start if the UPS(s) load is too high

Technical implementation idea:
	ethernet over power cables - http://en.wikipedia.org/wiki/Homeplug
	8 bit 0-255 levels you can assign on each server in the bios or similar
		0 means start as soon as there is power, regardless of what the UPS(s) say
		1 means start once the UPS(s) send out "level 1 start now"
		once the UPS sends out "level 255 start now" any level servers on a level below 255 may start now
		(yet unknown what happens when server connected to 2 UPSs receives different level information)
		(yet unknown if each power supply should have its own level, or it is for the entire server)

	Servers when plugged in may send out their level and ask "level Y, permission to start?" UPS(s) should answer (yet unknown what happens when 2 or more UPSs answer differently)
	Servers should always honor when an human presses the power On button.

	UPS(s) should regularly broadcast their state and existence over the "network" such that servers can get information from that.
	Server(s) should listen for broadcasts and note when the UPS(s) stop giving out information on a regularly interval

	All information in the network should optionally be cryptographically signed to be able to trust the source.


More information about the Nut-upsuser mailing list