[Nut-upsdev] Some questions on driver implementation and variable names

[Edgar Fuß]

I've just written an NUT driver to manage a Masterguard UPS connected  
via USB, and some questions arose.

Why I wrote a new driver? The servers in question only have two  
serial ports, so I want to use USB. I first wrote the low-level USB  
routines expecting to integrate them into the existing masterguard  
driver. However, that driver was so rudimentary I wrote my own one.  
It can be trivially extended to talk via a serial line.

Now to my questions:

In case there is some variable (like ups.power) the UPS does not  
directly exhibit, but which can be computed by other known values  
(nominal power, load); should I compute and set that variable or  
should I only set values directly obtained form the UPS?

There are variables for minimum and maximum observed input voltage,  
but not for frequencies. Is it OK to set input.frequency. 
{minimum,maximum}?

We have input.transfer.low and the like, but this UPS also gives me a  
frequency range outside which it will go offline. Any variable names  
for that?

Same for temeratures: We have ambient.temperature.alarm.{min,max} 
imum, but nothing nike it for ups internal temperatures.

I assume battery.runtime shold give the estimated runtime under  
current load. I also have nominal on-battery runtime for 100% and 50%  
load. Any names for those?

When running a battery test, apart from running until empty, I can  
set a time. Anything like ups.test.duration?

In case my setvar routine knows the name, but the value is illegal, I  
suppose I have to return STAT_SET_UINKNOWN despite the name being  
known, right?

If I accept a setvar(), do I have to dstate_setinfo() the variable or  
does some generic routine do so for me?

Does "calibrate" mean to run on battery until exhausted or seomething  
else?

The text for the "OB" status says "inverter is powering the load".  
Despite that, I assume that with an online UPS, I'm not supposed to  
always set that flag, but only when on battery, right? Am I right to  
believe that "OL" and "OB" are mutually exclusive?

Finally, I'm not sure I understand the different ups.delay.*  
variables correctly. When initiating a shutdown, there are two things  
I can set: The duration of the countdown (e.g. time from now to power- 
off) and the time from then until restarting the load (the UPS will  
always auto-power-on after a line failure). I guess the later is  
ups.delay.start and the former is ups.delay.reboot for  
shutdown.reboot.graceful, zero for shutdown.reboot and  
ups.delay.shutdown for shutdown.{return,stayoff}. Or am I getting it  
wrong?

Thanks for your help.