[Nut-upsuser] NUT reporting wrong voltage

Charles Lepple clepple at gmail.com
Thu Dec 6 04:18:47 GMT 2018

On Dec 5, 2018, at 5:17 PM, Crispin Proctor <crispin.proctor at gmail.com> wrote:
> Hi folks,
> I have an APC Back-UPS XS 1400U which is reporting the wrong input and output voltages.
> I am in the UK where our nominal voltage is 240 - not 110 :)

You're doing somewhat better than the XS 1200, and not quite as good as the XS 1500. Since 1400 is between those two... :-)



> If I connect with parachute via USB it reports correctly. 
> Is there a config I can update to tell it what it should be reporting? Some wrong conversion?
I don't want to blame APC without doing due diligence, but a number of other vendors seem to have errors in their HID report descriptors that produce similar scaling problems. (It's the HID equivalent of not closing out a parenthesis on a prior line.)

We do have a plan to add in HID descriptor patching: https://github.com/networkupstools/nut/issues/169

To confirm if this is the same problem, can you kill usbhid-ups, then start it back up with '-DDD'? (This is a little different than running the NUT startup scripts, or upsdrvctl - just use 'ps auxww | grep [u]sbhid-ups' to find the command line for the driver, then add in the debug flags. You can grab both stdout and stderr, and send it to a log file. For Debian, it will probably look something like this:

/lib/nut/usbhid-ups -a ups -DDD 2>&1 | tee /tmp/APC_Back-UPS_XS_1400U.debug.log

It will run indefinitely, but we just need that first few pages before it goes into the polling loop, so you can stop it with Ctrl-C.

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