WattNode Wide-Range Modbus Power Meter, RS-485 Network


The WattNode® Wide-Range Modbus® meter measures bi-directional energy (kWh), power (kW demand), voltage, current, power factor, and 90+ Modbus registers. The Wide-Range meter works on all electrical services from 100 to 600 Vac, single-phase or three-phase, wye or delta. It can be powered line-to-neutral or line-to-line. The meter communicates using Modbus® RTU over an RS-485 network. Meter purchase page.

New Features

  • 100-600 Vac, wye and delta, single-phase and three-phase with a single model
  • Correct wiring errors remotely
    • Change a CT’s polarity
    • Change a CT to a different line voltage
  • SunSpec certified
  • Updates readings every 100 ms
  • Class 0.5 accuracy


  • Meets the ANSI C12.20-2010 standard for revenue metering when used with accuracy class 0.3 or better CTs.
  • Meets the ANSI C12.1-2008 standard for revenue metering when used with accuracy class 0.6 or better CTs.


  • True RMS Energy: kWh (phase A, B, C, and sum of phases)
  • True RMS Power: Watts (phase A, B, C, and sum of phases)
  • Reactive Energy: kVAR-hours (phase A, B, C, and sum of phases)
  • Reactive Power: VARs (phase A, B, C, and sum of phases)
  • Power Factor: (phase A, B, C, and sum of phases)
  • RMS voltage (phase A, B, C, and average)
  • RMS current (phase A, B, C, and average)
  • AC Line Frequency
  • Demand and peak demand
  • And 90+ additional measurements

Diagnostic LEDs

Our diagnostic LEDs provide a per-phase indication of power (green flashing) and negative power (red flashing) to help troubleshoot connection problems, like reversed CTs, or excessive line voltage. The red/yellow/green communication LED indicates traffic, configuration problems, and other conditions. See the manual for full descriptions.

WattNode Wide-Range Key Features

Key Features
Meets ANSI C12.1 for use in revenue grade metering
Nominal accuracy 0.5% (see Installation and Operation Manual (PDF, 82 pages) for details)
True RMS power even with leading or lagging power factor and chopped or distorted waveforms
SunSpec Certified™ register map supported (see SunSpec Certification Certificate)
Measure variable speed motor drives used in HVAC, refrigeration, and pumping systems
Small form factor for easy installation inside most electrical panels, see an example WattNode Modbus Installation
Pluggable screw terminal blocks for easy wiring
UL, cUL Listed – Tested for safety and approved for use throughout North America and the European Union.
Assembled in USA, qualified under the Buy American provision in the American Recovery and Reinvestment Act of 2009 (ARRA).
Five year warranty
Large selection of Current Transformers with safe 0.333 Vac low voltage outputs:

  • Split core CTs for safe and quick installation
  • Solid core CTs are less expensive and prevent tampering
  • CTBL large split-core CTs for high currents (standard and custom sizes up to 6000A)
  • CTRC Rogowski Coils for tight spaces where rigid CTs do not fit (four lengths, 250A to 6000A)


WattNode Wide-Range Modbus Overview

WattNode Wide-Range Modbus Meter

WattNode® Modbus® – Specifications


  • Nominal ±0.5%
  • Meets the accuracy requirements of the ANSI C12.1 standard when used with CCS CTs rated for IEEE C57.13 class 0.6 accuracy (see Current Transformers Overview).
  • Meets the ANSI C12.20-2010 class 0.5 standard for revenue metering with CTs when used with class 0.3 CTs (see Current Transformers Overview).


  • Nominal Operating Voltage Range: 100 to 600 Vac (line-to-neutral or line-to-line)
  • Line Frequency: 45 to 65 Hz
  • Minimum Operating Voltage: 85 Vac
  • Absolute Maximum Voltage: 690 Vac
  • Supply Watts: <2 W
  • Supply Volt-Amperes: <4 VA
  • Power Factor: 0.6

Current Transformer Inputs

  • Voltage Mode:
    • Nominal Input Voltage (At CT Rated Current): 0.33333 Vac RMS
    • Absolute Maximum Input Voltage: 5.0 Vac RMS
    • Input Impedance at 50-60 Hz: 23 kΩ
  • Current Mode:
    • Nominal Input Current (At CT Rated Current): 40 mA RMS
    • Absolute Maximum Input Current: 200 mA RMS
    • Input Impedance at 50-60 Hz: 10 Ω

Modbus Communication

  • Protocol: Modbus RTU (binary)
  • Baud Rates: DIP switch selected 9600 or 19200. Register configurable: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 76800, and 115200 baud
  • Address (ID) range: DIP switch selected 1 to 63. Register configurable: 1 to 247
  • Duplex: Half (two-wire twisted pair with shield drain wire)
  • Parity:
    • Standard (default): N81 (no parity, eight data bits, one stop bit)
    • Optional: E81 (even parity, eight data bits, one stop bit)
    • Optional: N82 (no parity, eight data bits, two stop bits)
  • Modbus Buffer: 256 bytes
  • Response Time (typical): 5 to 25 milliseconds (may be longer immediately after a Modbus write command, while values are saved to non-volatile memory)

EIA RS-485 Interface

  • Output Isolation: 4500 Vac RMS
  • Driver Output:
    • Voltage (Open Circuit): ± 6 Vdc maximum
    • Voltage (54Ω load): ± 1.5 Vdc minimum
    • Current (54Ω load): ± 60 mA typical
    • Rise Time (54Ω || 50 pF load): 900 nS typical
  • Receiver:
    • Receiver Common-Mode Voltage Range: –7 to +12 Vdc maximum
    • Receiver Sensitivity: ±200 mV
    • Receiver Bus Load: 1/8 unit load (up to 256 WattNode meters per subnet)


  • Safety: meets European Parliament Directive 2014/35/EU: Low Voltage Directive
  • UL Listed (U.S. and Canada), file number E359088
  • UL / IEC 61010-1, 3rd Edition
  • CAN/CSA-C22.2 No. 61010-1-12, 3rd Edition
  • FCC Class B, EN 55022 Class B
  • EMC: meets European Parliament Directive 2014/30/EU: Electromagnetic Compatibility
    • EMC Requirements: EN 61326-1: 2013, industrial locations
    • Radiated Emissions: CISPR / EN 55011, Class B
    • Conducted Emissions: CISPR / EN 55011, Class B
    • Electrostatic Discharge: EN/IEC 61000-4-2: (B) Self-Recovering
    • Radiated RF Immunity: EN/IEC 61000-4-3: (A) NDegradation
    • Electrical Fast Transient / Burst: EN/IEC 61000-4-4: (A) NDegradation
    • Surge Immunity: EN/IEC 61000-4-5: (A) NDegradation
    • Conducted RF Immunity: EN/IEC 61000-4-6: (A) NDegradation
    • Power Frequency H-field Immunity: EN/IEC 61000-4-8: (A) NDegradation
    • Voltage Dips, Interrupts: EN/IEC 61000-4-11: (B) Self-Recovering


  • Operating Temperature: –40°F to 176°F (–40°C to +80°C)
  • Altitude: Up to 9842 ft (3000 m)
  • Operating Humidity: 5 to 90% relative humidity (RH) up to 40°C, decreasing linearly to 50% RH at 55°C.
  • Pollution: POLLUTION DEGREE 2 – Normally only non-conductive pollution; occasionally, a temporary conductivity caused by condensation must be expected.
  • Degree of Protection: IP40 (>1 mm solids, no protection from liquids)
  • Indoor Use: Suitable for indoor use.
  • Outdoor Use: Suitable for outdoor use if mounted inside an electrical enclosure (Hammond Mfg., Type EJ Series or equivalent) rated NEMA 3R or 4 (IP 66)


Case Dimensions

(Click on the image for a larger view.)

  • Enclosure:
    • High impact, ABS/PC plastic
    • Flame Resistance Rating: 94V-0, IEC FV-0
    • Size: 5.63 × 3.34 × 1.5 in. (143 × 85 × 38 mm)
    • Weight: 8.2 oz (233 g )
  • Connectors: Euroblock style pluggable screw terminal blocks
  • Green: 22 to 12 AWG (0.32 to 2.5 mm2), 600 V, screw torque: 3.5 lbf·in (0.4 N·m)
  • Black: 22 to 12 AWG (0.32 to 2.5 mm2), 300 V, screw torque: 3.5 lbf·in (0.4 N·m)

Modbus is a registered trademark of Modbus Organization, Inc.

WattNode® Wide-Range Modbus® — Downloads



Manuals, Technical Documents, and JAR File

Support Links

  • Application Notes
  • Support Articles

Firmware Updates

The WattNode Wide-Range Modbus meter firmware is periodically updated. The firmware cannot be field upgraded, so the meter must be returned to the factory for firmware updates. There is a nominal charge for firmware updates unless they are needed to fix a bug under warranty. Unless you are experiencing problems, there is generally no reason to update the firmware.

See WND Series WattNode Modbus Firmware Versions page for the full list of versions.

Modbus is a registered trademark of Schneider Electric USA, Inc.

WattNode Wide-Range Modbus® – Options

Many of the WattNode® Wide-Range Modbus® registers can be custom configured at the factory for an additional 10% programming charge. See the WattNode Wide-Range Modbus manual (pdf) for more information about available option.

Meters with options cannot be ordered on line. Please contact our Sales Team at sales@ctlsys.com or call 303-444-7422 to request a quote or place an order for meters with options.

General Options

Communication Options

Unless otherwise specified, the factory default communications options are: no parity, eight data bits, and one stop bit.

  • Option EP – Factory configure the Modbus RS-485 communications to default to even parity (E81)
    This can be field configured using the ParityMode register if you have meters that were ordered without this option and you need even parity this can be overridden or turned off in the field by changing the ParityMode register.
  • Option 19K – Factory configure the RS-485 communications to 19,200 baud.
    This can be changed in the field by switching the baud rate DIP switch, or by writing to the Baud register. If you write “0” to the BaudRate register, then the DIP switch setting will control the baud rate.
  • Option 38K – Factory configure the RS-485 communications to 38,400 baud. Position 8 of the DIP switch will be ignored.
    This can be changed in the field by writing a new value to the BaudRate register. If you write “0” to the BaudRate register, then the DIP switch setting will control the baud rate.
  • Option TCP-RTU – Configure the communications to the Modbus TCP-RTU protocol option for use with RS-485 to Ethernet converters (serial device adapters).
    This can be field configured or disabled with the ModbusMode register.
  • Option AD – Factory configure the Modbus address.
    This can be changed in the field by by writing a new address to the Address register. If you write 0 (zero) to the Address register, then the DIP switch setting will specify the Modbus address.

Note: All WattNode Modbus meters can have their communication settings restored to factory shipped values by setting all DIP switch positions to “0” for ten seconds. If an communication option has been ordered, the meter will restore to include the settings from any options.

Meter Element Configuration Options

See Also