Nut upsuser - Apr 2024 - CyberPower CST150UC: Question re: battery.runtime.low configuration settings

I would like to solicit some feedback re: the 
battery.runtime.lowconfiguration settings through NUT. I was able to set 
the value using the 'upsrw' command but when I did a 'upsc' the 
configuration seems incorrect. Please see below for details. Thank you

OS name and version:
 ?? ?Description:??? Debian GNU/Linux 12 (bookworm)
 ?? ?Release:??????? 12
 ?? ?Codename:?????? bookworm

exact NUT version:
 ?? ?Version: 2.8.0-7

NUT installation method:
 ?? ?apt install nut

exact device name and related information:
https://www.cyberpowersystems.com/product/ups/battery-backup/cst150uc/
 ?? ?device.model: CST150UC
 ?? ?driver.version: 2.8.0
 ?? ?driver.version.data: CyberPower HID 0.6
 ?? ?driver.version.internal: 0.47
 ?? ?driver.version.usb: libusb-1.0.26 (API: 0x1000109)
 ?? ?ups.vendorid: 0764

supported UPS variables (default values PRIOR to configuration change 
attempt)
 ?? ?upsrw CST150UC
 ?? ???? ??? [battery.charge.low]
 ?? ???? ??? Remaining battery level when UPS switches to LB (percent)
 ?? ???? ??? Type: STRING
 ?? ???? ??? Maximum length: 10
 ?? ???? ??? Value: 10

 ?? ???? ??? [battery.runtime.low]
 ?? ???? ??? Remaining battery runtime when UPS switches to LB (seconds)
 ?? ???? ??? Type: STRING
 ?? ???? ??? Maximum length: 10
 ?? ???? ??? Value: 300

 ?? ???? ??? [ups.delay.shutdown]
 ?? ???? ??? Interval to wait after shutdown with delay command (seconds)
 ?? ???? ??? Type: STRING
 ?? ???? ??? Maximum length: 10
 ?? ???? ??? Value: 20

 ?? ???? ??? [ups.delay.start]
 ?? ???? ??? Interval to wait before (re)starting the load (seconds)
 ?? ???? ??? Type: STRING
 ?? ???? ??? Maximum length: 10
 ?? ???? ??? Value: 30

set UPS variables (system will shutdown when 60 minutes of runtime is left)
 ?? ?upsrw -s battery.runtime.low=3600 -w CST150UC at localhost
 ??? SUCCESS

upsc CST150UC at localhost
 ?? ?battery.charge: 100
 ?? ?battery.charge.low: 10
 ?? ?battery.charge.warning: 20
 ?? ?battery.mfr.date: CPS
 ?? ?battery.runtime: 5125
 ?? ?battery.runtime.low: 16
 ?? ?battery.type: PbAcid
 ?? ?battery.voltage: 25.8
 ?? ?battery.voltage.nominal: 24
 ?? ?device.mfr: CPS
 ?? ?device.model: CST150UC
 ?? ?device.serial:
 ?? ?device.type: ups
 ?? ?driver.name: usbhid-ups
 ?? ?driver.parameter.offdelay: 60
 ?? ?driver.parameter.pollfreq: 30
 ?? ?driver.parameter.pollinterval: 2
 ?? ?driver.parameter.port: auto
 ?? ?driver.parameter.synchronous: auto
 ?? ?driver.version: 2.8.0
 ?? ?driver.version.data: CyberPower HID 0.6
 ?? ?driver.version.internal: 0.47
 ?? ?driver.version.usb: libusb-1.0.26 (API: 0x1000109)
 ?? ?input.voltage: 122.0
 ?? ?input.voltage.nominal: 120
 ?? ?output.voltage: 122.0
 ?? ?ups.beeper.status: disabled
 ?? ?ups.delay.shutdown: 60
 ?? ?ups.delay.start: -1
 ?? ?ups.load: 10
 ?? ?ups.mfr: CPS
 ?? ?ups.model: CST150UC
 ?? ?ups.productid: 0601
 ?? ?ups.realpower.nominal: 900
 ?? ?ups.serial:
 ?? ?ups.status: OL
 ?? ?ups.test.result: No test initiated
 ?? ?ups.timer.shutdown: -60
 ?? ?ups.timer.start: -60
 ?? ?ups.vendorid: 0764

The value changed to battery.runtime.low: 16, instead of 3600. I don't 
understand why, because executing the command resulted in SUCCESS.

In comparison executing (never powers on the load, even when main power 
returns)
upsrw -s ups.delay.start=-1 -w CST150UC at localhost
resulted in the correct value being set.

I hope someone will be able to provide some guidance. : )

Thank you
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> On Apr 23, 2024, at 3:51?PM, tim.o via Nut-upsuser <nut-upsuser at
alioth-lists.debian.net> wrote:
> 
> The value changed to battery.runtime.low: 16, instead of 3600. I don't
understand why, because executing the command resulted in SUCCESS.
Unfortunately, the SUCCESS response is just saying that upsrw was able to send
that request to upsd (i.e. the username/password were correct). As you saw, the
real proof is in what you read back from upsc.

Have you tried any other values? 3600 is hex 0xe10, and 16 is 0x10, so it is
quite possible the UPS is using an 8-bit field to store battery.runtime.low.
I'm guessing the maximum is going to be 255.

This is not entirely surprising - we have a GitHub issue label specific to CPS
for issues with their USB HID protocol implementation.

-- 
Charles Lepple
clepple at gmail