[Nut-upsuser] APC Easy UPS

[d tbsky]

Hi:
    just got an APC UPS on hand. it's a strange new one, not smart-ups
or back-ups. it's APC Easy UPS:
https://www.schneider-electric.com/en/product-range/65883-easy-ups-on-line/

   I don't know what's different. this series are all online UPS and
they are cheap.

   it comes with serial and usb interface. with serial interface I can
use apcsmart to connect. but with usb interface no driver works. i
tried apcsmart and usbhid-ups. the usb interface seems just a serial
converter, it brings /dev/ttyACM0 under linux and lsusb shows:

       ID 04e2:1410 Exar Corp. XR21V1410 USB-UART IC

  I wonder if it can work under usb mode?  if I connect both serial
and usb cable. the serial port for nut become "Data stale". so usb and
serial seems share the same line.

  for reference, nut report below under serial with apcsmart driver:

battery.alarm.threshold: 0
battery.charge: 100.0
battery.charge.restart: 00
battery.date: 10/12/18
battery.packs: 001
battery.runtime: 21540
battery.runtime.low: 120
battery.voltage: 086.9
battery.voltage.nominal: 072
device.mfr: APC
device.model: SRV 3K A
device.serial: 9S1838A65050
device.type: ups
driver.name: apcsmart
driver.parameter.pollinterval: 2
driver.parameter.port: /dev/ttyS0
driver.parameter.synchronous: no
driver.version: 2.7.4
driver.version.internal: 3.1
input.frequency: 59.99
input.quality: FF
input.transfer.high: 144
input.transfer.low: 96
input.transfer.reason: simulated power failure or UPS test
input.voltage: 112.5
input.voltage.maximum: 112.8
input.voltage.minimum: 112.4
output.current: 00.00
output.voltage: 119.4
output.voltage.nominal: 120
ups.delay.shutdown: 180
ups.delay.start: 000
ups.firmware: 441.08CT.I
ups.id: UPS_IDEN
ups.load: 000.0
ups.mfr: APC
ups.mfr.date: 10/12/18
ups.model: SRV 3K A
ups.serial: 9S1838A65050
ups.status: OL
ups.temperature: 030.6
ups.test.interval: 1209600
ups.test.result: NO