Selecting a specific UPS¶

As mentioned above, the driver ignores the "port" value in ups.conf. Unlike previous versions of this driver, it is now possible to control multiple UPS units simultaneously with this driver, provided they can be distinguished by setting some combination of the device-matching options. For instance:

[mge]


        driver = usbhid-ups


        port = auto


        vendorid = 0463
[tripplite]


        driver = usbhid-ups


        port = auto


        vendorid = 09ae

USB Polling and Interrupt Transfers¶

The usbhid-ups driver has two polling intervals. The "pollinterval" configuration option controls what can be considered the "inner loop", where the driver polls and waits briefly for "interrupt" reports. The "pollfreq" option is for less frequent updates of a larger set of values, and as such, we recommend setting that interval to several times the value of "pollinterval".

Many UPSes will respond to a USB Interrupt In transfer with HID reports corresponding to values which have changed. This saves the driver from having to poll each value individually with USB Control transfers. Since the OB and LB status flags are important for a clean shutdown, the driver also explicitly polls the HID paths corresponding to those status bits during the inner "pollinterval" time period. The "pollonly" option can be used to skip the Interrupt In transfers if they are known not to work.

Repetitive timeout and staleness¶

Some models tends to be unresponsive with the default polling frequency. The result is that your system log will have lots of messages like:

usb 2-1: control timeout on ep0in
usb 2-1: usbfs: USBDEVFS_CONTROL failed cmd usbhid-ups rqt 128 rq 6 len 256
ret -110

In this case, simply modify the general parameter "pollinterval" to a higher value (such as 10 seconds). This should solve the issue.

Note that if you increase "pollinterval" beyond 10 or 15 seconds, you might also want to increase "pollfreq" by the same factor.

Got EPERM: Operation not permitted upon driver startup¶

You have forgotten to install the hotplug files, as explained in the INSTALLATION section above. Don’t forget to restart hotplug so that it applies these changes.

Unattended shutdowns¶

The hardware which was used for development of this driver is almost certainly different from what you have, and not all manufacturers follow the USB HID Power Device Class specifications to the letter. You don’t want to find out that yours has issues here when a power failure hits your server room and you’re not around to manually restart your servers.

If you rely on the UPS to shutdown your systems in case of mains failure and to restart them when the power returns, you must test this. You can do so by running upsmon -c fsd. With the mains present, this should bring your systems down and then cycle the power to restart them again. If you do the same without mains present, it should do the same, but in this case, the outputs shall remain off until mains power is applied again.

UPS cuts power too soon¶

Note that many Cyber Power Systems (CPS) models tend to divide offdelay by 60 and round down, so the minimum advisable value is 60 (seconds) to avoid powering off immediately after NUT sends the shutdown command to the UPS.

UPS does not set battery.charge.low but says OK¶

Note that many Cyber Power Systems (CPS) models tend to allow only certain values for battery.charge.low and anything outside of the set of allowed values are rounded or ignored.

A shell loop like this can help you map out the allowed values:

for i in `seq 90 -1 0`; do echo "set to $i"; \


    upsrw -s battery.charge.low=$i -u * -p * cps-big; \


    sleep 1; upsc cps-big battery.charge.low; echo ""; \
done

For example, for CPS PR1000LCDRTXL2U model, the only allowed values are [60,55,50,45,40,35,30,25,20] and in some cases, your UPS may effectively not support a value of 10 for the battery.charge.low setting.

The core driver¶

nutupsdrv(8)

Internet resources¶

The NUT (Network UPS Tools) home page: https://www.networkupstools.org/