[Nut-upsuser] Incorrect Values From usbhid-ups

[Charles Lepple]

On Mar 26, 2014, at 2:15 PM, Bill S wrote:

> I have attached two .gz files of the driver output with the -DDDD
> option.  One is for when the unit is on the line AC and the the other
> is when it is on battery so that there are at least two points of
> reference.
> 
> In earlier tests, I did note that when the unit was placed on battery
> that the upsstats.cgi screen reported that the input voltage from 119V
> to 120V and did not go to zero as I expected it would.

Hmm, I wonder if it just wasn't polling fast enough?

From the AC file:

   0.263461	Report[get]: (3 bytes) => 0f 77 00
   0.263469	Path: UPS.Input.Voltage, Type: Feature, ReportID: 0x0f, Offset: 0, Size: 16, Value: 119

On battery:

   0.082947	Report[get]: (3 bytes) => 0f 00 00
   0.082957	Path: UPS.Input.Voltage, Type: Feature, ReportID: 0x0f, Offset: 0, Size: 16, Value: 0


> I also noted that the output voltage remained at 136V.

This value (136) is suspiciously a Logical Minimum that was set elsewhere in the HID Report Descriptor.

AC:

   0.263726	Report[get]: (3 bytes) => 12 77 00
   0.263735	Path: UPS.Output.Voltage, Type: Feature, ReportID: 0x12, Offset: 0, Size: 16, Value: 136

Note that 0x77 == 119 decimal.

Battery:

   0.083198	Report[get]: (3 bytes) => 12 78 00
   0.083207	Path: UPS.Output.Voltage, Type: Feature, ReportID: 0x12, Offset: 0, Size: 16, Value: 136

I will have to consult the NUT code and the HID documentation to see whether the issue is in the HID parser or the UPS HID descriptor.

-- 
Charles Lepple
clepple at gmail