WattNode® Modbus® – Specifications

These specifications apply to the following two families of WattNode meters for the Modbus protocol:

Modbus Communication

  • Protocol: Modbus RTU (binary)
  • Baud Rates: 2,400, 4,800, 9,600,19,200, and 38,400 baud
  • Duplex: Half (two-wire plus common)
  • Parity (default): N81 (no parity, eight data bits, one stop bit)
  • Modbus Buffer: 256 bytes
  • Response Time (typical): 5 to 25 milliseconds

EIA RS-485 Interface

  • Driver Output Voltage (Open Circuit): ± V maximum
  • Driver Output Voltage (54Ω load): ± 1.5 V minimum
  • Driver Output Current (54Ω load): ± 60 mA typical
  • Driver Output Rise Time (54Ω || 50 pF load): 900 nS typical
  • Receiver Common-Mode Voltage Range: –7 to +12 Vdc maximum
  • Receiver Sensitivity: ±200 mV
  • Receiver Bus Load: 1/8 unit load

Electrical

  • Line powered
  • Operating Voltage Range: –20% to +15% of nominal
  • Power Line Frequency: 50 or 60 Hz
  • CT Input: 0.333 Vac nominal, 0 to 0.5 Vac operating, 3 Vac maximum

Measurement Configurations

Models available for:

  • Single phase: two or three wire
  • Three phase: four wire wye
  • Three phase: three wire delta
  • Three phase: four wire delta

Accuracy

WattNode Modbus

  • 0.5% nominal (see manual for details)

WattNode Revenue Modbus

  • 0.5% nominal (see manual for details)
  • 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 Revenue Grade CTs).
  • Models RWNC-3Y-208-MB, RWNC-3D-240-MB and RWNC-3Y-480-MB are certified by MET Laboratories to meet ANSI C12.1. MET Labs is a nationally recognized testing laboratory (NRTL).

Regulatory

  • FCC Class B, EN 55022 Class B
  • UL and cUL Listed (UL 61010-1), file number E312220
  • CE Mark and RoHS Declaration of Conformity
  • Immunity: EN 61326: 2002 (Industrial Locations)

Environmental

  • Operating Temperature: –30°C to +55°C (–22°F to +131°F)
  • Altitude: Up to 2000 m (6560 ft)
  • 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.
  • Indoor Use: Suitable for indoor use.
  • Outdoor Use: Suitable for outdoor use when mounted inside an electrical enclosure (Hammond Mfg., Type EJ Series) that is rated NEMA 3R or 4.

Mechanical

WattNode-Case-Dimensions.png

Case Dimensions

(Click on the image for a larger view.)

  • Enclosure:
    • High impact, ABS plastic
    • Flame Resistance Rating: 94V-0, IEC FV-0
    • Size: 5.63 × 3.34 × 1.5 in. (143 × 85 × 38 mm)
    • Weight: 10.8 oz (305 g)
  • Connectors: Euroblock style pluggable screw terminal blocks
    • Green: 22 to 12 AWG (1.0 to 3.2 mm), 600 V
    • Black: 22 to 12 AWG (1.0 to 3.2 mm), 300 V

Modbus is a registered trademark of Modbus Organization, Inc.


Keywords: C12