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