[Nut-upsdev] APC SmartUPS 750 (SUA750) missing ambient data with usbhid-ups

[Ric Anderson]

I have a SmartUPS 750 (SUA750) which has the temperature and humidity
SmartSlot card installed.  When NUT 2.2 communicates with this UPS over
/dev/ttyS0 using apcsmart, using the APC Smart cable connected to the
SUA750 serial port, and this ups.conf:
   [su700]
         driver=apcsmart
         port = /dev/ttyS0
I can see the ambient temperature and humidity data with "upsc su700 at localhost".

If I switch the driver configuration to use the USB port on the SUA750,
disconnect the serial cable, hook up the USB cable, and restart everything
using this ups.conf:
   [su700]
         driver=usbhid-ups
         port = auto
         vendorid=051d
then I no longer see the ambient data with upsc, and several other fields
in the output have different names and/or are missing.  The basic ups
data is still there, so obviously there is some communication going on
over the USB interface.

Newer servers around here seem to lack serial ports, so I really need
to migrate to USB monitoring, but the lack of environmental information
via usbhid-ups is a deal breaker.

If I connect the same USB cable to a Windows laptop with APC's PowerChute
Business Basic (which came with the UPS), I can read the ambient temperature
and humidity, so the data is available on the USB link.

Any ideas on how to get usbhid-ups to pass along the same data in Linux?

Thanks,
ric at opus1.com