[Nut-upsdev] APC protocols and drivers (was: Documenting the NUT driver-qualification process)
tedm at mittelstaedt.us
Wed Jul 30 02:40:32 UTC 2014
On 7/29/2014 1:32 PM, Arnaud Quette wrote:
> Hi Ted
> there was a drift from the initial topic.
> worth a new thread!
> 2014-07-27 9:13 GMT+02:00 Ted Mittelstaedt <tedm at mittelstaedt.us
> <mailto:tedm at mittelstaedt.us>>:
> On 7/26/2014 12:18 PM, Arnaud Quette wrote:
> Hi Eric,
> sorry for the lag, summer time...
> I'm first seconding Charles comments
> 2014-07-09 12:31 GMT+02:00 Eric S. Raymond <esr at thyrsus.com
> <mailto:esr at thyrsus.com>
> <mailto:esr at thyrsus.com <mailto:esr at thyrsus.com>>>:
> I think the time for me to get involved in NUT
> documentation has come
> welcome back
> Late last week I had to buy a UPS under time pressure. The
> Eaton unit
> that thus project gifted me with in 2006(?) died during a
> thunderstorm watch, so it was off to MicroCenter to get a
> I wound up buying an APC BN700MC. It was what they had in the
> performance range I needed. The removable battery door was
> Based on the experience, I have updated the UPS HOWTO:
> The bad news, however, is that (a) this is not a
> NUT-supported device,
> I've logged an entry for the APC Modbus:
> and (b) the (poorly documented) NUT process for discovering and
> customizing a driver failed at the first step. Running
> gave a driver fail message containing no clues as to how to
> yup, definitely room for enhancement!
> I've got some ideas, beside from the obvious need to improve the
> documentation, that I'll like to discuss.
> This is definitely USB and probably a fairly generic hidups
> There is no good reason for customizing a driver profile to be
> so difficult.
> well, I'm unsure since I'm just opening this "APC Modbus Pandora
> but if I understand correctly, your new unit is a microlink one.
> HIS UPS is a BackUPS not a SmartUPS. Originally the APC BackUPS DID NOT
> SUPPORT any Smart protocol (the original UPSLink protocol)
> But over the years it's been observed that APC has somewhat "fudged" on
> the BackUPS UPSes. Newer ones did appear to implement the UPSlink
> protocol over USB.
> Microlink protocol is officially only for APC SmartUPSes. Officially,
> what your supposed to get with a BackUPS is dumb signalling only. But,
> with the newer BackUPSes that have USB output, some seemed to act like
> SmartUPSes even though they were not.
> APC has very much blurred the line on the model BN UPSes. These are the
> APC UPSes that look like an oversized power strip. That's the one
> that he has. They seem to have dropped monitoring ports completely
> on these UPSes that are under 700VA in size. They used to make
> monitoring ports
> on these UPSes all the way down to 350VA. But the current models,
> only the 700VA unit like the one he bought, still support the
> monitoring port. That port is the special wide RJ45 that has 10
> conductors not 8.
> It is selectable between serial and USB depending on what cable is used
> with it.
> though the serial version should be Modbus only,
> There is no "serial only" APC UPS that supports Modbus, in fact no
> APC smart UPS since the Microlink protocol was implemented has been
> "serial only", all have been dual-use Serial and USB.
> I can't say at first if
> the USB ones implement if full Modbus over HID or any other mean.
> I would need traces to give more info.
> The BackUPSes with USB ports might implement full UPSlink over HID.
> Or they might implement Microlink over HID
> Or they might implement nothing like either of that.
> But they definitely don't implement Modbus.
> It is best I think to refer to BackUPS and SmartUPS in the
> documentation. Please do not refer to APC UPSes in a generic
> fashion. And please don't assume that any APC BackUPS implements any
> protocol over USB or Serial unless you have directly tested it. APC
> BackUPS upses are the "cheap, poor relations" and are for consumers and
> penny-pinching businesses that are too cheap to spend a couple
> hundred bucks on decent gear. Purchasers who want full
> functionality should be
> encouraged to buy an APC SmartUPS.
> thanks for these details, still too blurry for the little time I
> currently have!
> my aim there is not to understand APC offering. I don't have time nor
> interest in that!
> my aim is simply to have people happy, which generally means supporting
> their unit, so developing code. period.
> So, if someone (maybe you):
> 1) can clarify APC situation WRT protocols (both serial and USB ;
> microlink / UPSLink / whatever-nameLink)
OK here's the general rule of thumb FOR SMARTUPS ONLY:
APC models with a model # starting with SUA - UPSLink
APC models with a model # starting with SMT - Microlink
APC models with a model # starting with SMT dated 2014
or later - Microlink & Modbus
A firmware update exists that can make SOME Microlink-only into
Microlink & Modbus
Here's the general rule of thumb for BACKUPS:
Backups with Serial Port - dumb signalling.
Backups with Serial & USB port - dumb signalling on serial,
HID UPS signalling on USB
> 2) and has access to unit(s) to provide sniff
I have a number of different APC UPSes. I can setup a test Linux server
that you would have root access to with both serial and USB ports
plugged into whatever version of APC UPS you want to play with.
> I can check to develop some generic code in "blind mode" (no access to
> devices), for modbus or else, that also supports APC.
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