[Nut-upsuser] MGE ESV+ and Power Trim

David Baker david at baker.im
Sun Mar 12 00:15:35 UTC 2017

Hi Arnaud & Charles,

You’ll have to forgive my low level of Linux Understanding here….

I downloaded the source files, modified the appropriate driver file, re-compiled it (all of this was a lot of research and learning!)

When I use the new driver I get –

Network UPS Tools - UPS driver controller 2.7.2
Network UPS Tools - MGE UPS SYSTEMS/U-Talk driver 0.93 (
Can't chdir to /var/state/ups: No such file or directory
Driver failed to start (exit status=1)

The new .h file reads as this –

/* Output page */
        { "output.voltage", 0, 0, "Lv", "%05.1f", VOLT, TRUE },
        { "output.voltage.nominal", ST_FLAG_RW | ST_FLAG_STRING, 5, "Lv ?", "%05.1f", VOLT, TRUE },
        { "output.current", 0, 0, "Lc", "%05.1f", AMPERE, TRUE },

If I copy the old driver back, it works fine – so I’m guessing I’ve got something wrong with the compile or syntax!

Welcome your thoughts – the ESV22+ was a beast I came across which didn’t work – I managed to pick up some replacement batteries and it’s now protecting a load of audio and comms equipment in a charitable community centre in Northern Romania!

Thanks again


It's a long time since I've not dive into the UTalk code and devices. The last time was more than a decade ago.Happy to see some ESV+ alive :)
Then, even reading the spec, I'm not sure what was the exact difference between Lv and Iv, at least for a small UPS like ESV+.
So you can add the following line after "output.voltage in mge-utalk.h:

"{ "output.voltage.nominal", ST_FLAG_RW | ST_FLAG_STRING, 5, "Lv ?", "%05.1f", VOLT, TRUE },"
By adding the above, you'll be able to have the nominal output voltage reading and report (Lv ?) and to use upsrw to set nominal output voltage (Lv 24000).
Please tell us back if the above works fine for you, so that we can update the driver.
Otherwise, simply test by replacing the "Lv ?" with "Iv ?".
thanks and cheers,

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