meanwell_ntu - Man Page

Driver for Mean Well NTU series inverter/UPS units

Synopsis

meanwell_ntu -h

meanwell_ntu -a UPS_NAME [OPTIONS]

Note

This man page documents the hardware-specific features of the meanwell_ntu driver. For general information about NUT drivers, see nutupsdrv(8).

Description

The meanwell_ntu driver provides support for Mean Well NTU series inverter/UPS units that implement the vendor’s ASCII serial protocol.

This driver is currently experimental and intended for early adopters. Reported variables and behavior may evolve as additional models and firmware revisions are tested.

Supported Hardware

The driver is known to work with the following NTU models:

NTU-1200
NTU-1700
NTU-2200
NTU-3200

Supported DC-voltage variants include:

NTU-1200-112, -124, -148
NTU-1700-112, -124, -148
NTU-2200-112, -124, -148
NTU-3200-212, -224, -248

Other NTU-series devices using the same protocol may also work.

Communication uses a 9600-8-N-1 serial connection via RS-232 or a USB-serial adapter seen by the operating system as a serial port, e.g. /dev/ttyUSB0 (on Linux).

Cables

MEAN WELL p/n: RJ11-RS232

A straight-through serial cable (no modem control) is required.

USB-to-RS-232 adapters work as long as they expose a standard TTY device.

Configuration

The driver is configured via ups.conf(5).

A minimal configuration:

[meanwell-ntu]
    driver = meanwell_ntu
    port   = /dev/ttyUSB0
    desc   = "Mean Well NTU-1200-124"

Required parameters

Example standard parameters:

driver: Must be set to meanwell_ntu.
port: The serial/USB tty device (e.g. /dev/ttyS0, /dev/ttyUSB0).

Optional parameters

This driver currently relies only on standard NUT parameters:

pollinterval: Interval between status polls (default: 2 seconds).
synchronous: Serial I/O mode as documented in nutupsdrv(8).

Instant Commands

The following instant commands are supported when the connected hardware implements them (see upscmd(8)):

load.off: Request shutdown of inverter output and load power-off (vendor command C100000000000000).
load.on: Request inverter output power-on (vendor command C010000000000000).

Support varies across firmware revisions; test before relying on them.

Status and Variables

The driver regularly sends the Q (status) and I (info) commands and maps their fields to standard NUT variables.

Selected read-only variables

battery.voltage: Battery/DC bus voltage (V).
battery.charge: Remaining capacity (%).
battery.alarm.voltage: Low-voltage alarm threshold (V).
battery.shutdown.voltage: Low-voltage shutdown threshold (V).
input.voltage: Utility AC input voltage (non-zero in line or bypass mode).
output.voltage: Inverter output voltage (V).
output.frequency: Output frequency when running on battery (Hz).
ups.temperature: Inverter temperature (°C).
ups.load: Approximate load percentage, derived from PPP bits.
device.mfr: Manufacturer string (typically MEANWELL).
device.model, ups.model: Model descriptor (e.g. NTU-1200-124).
device.serial: Serial number when reported.
device.firmware: Firmware revision string.

UPS status flags

The NTU protocol exposes a 19-bit status word.

The driver maps selected bits into ups.status keywords:

OB: On battery / inverter mode.
BYPASS: Bypass mode active.
OL: Utility present / online.
LB: Battery low.
OVER: Over-temperature condition.

The raw bit fields are also exported as informational variables such as battery.low, utility.present, bypass.mode, overtemp, etc.

Limitations

This driver is marked experimental:

Protocol interpretation based on limited test samples.
Some fields in Q/I responses are currently unused.
Load and capacity reporting may be refined with further testing.
Shutdown and restart behavior is basic and may not integrate with all NUT power-path logic.

For debugging, run the driver with high verbosity, e.g.:

/usr/local/ups/bin/meanwell_ntu -DDDDD -a meanwell-ntu

Please include model, firmware version, and operating mode details when reporting issues.