WattNode^® Modbus

WattNode Modbus

The WattNode Modbus is a kilowatt hour kWh energy and power meter that communicates on a EIA RS-485 network, measures 1, 2, or 3 phases with voltages from 120 to 600 volts alternating current VAC and 5 to 6,000 amps in delta (phase to phase) and wye (phase to neutral) configurations.

Measurements

• Supports floating point and integer registers
• True RMS Power - Watts (Phase A, B, C, all phases)
• Reactive Power - VARs (Phase A, B, C, all phases)
• Power Factor (Phase A, B, C, all phases)
• True RMS Energy - Watthours WH kWh (Phase A, B, C, all phases)
• Reactive Energy - VAR-hours (All Phases)
• AC Frequency
• RMS Voltage (Phase A, B, C)
• RMS Current (Phase A, B, C)
• Demand
• Peak Demand

Features

• Small form factor for easy installation inside most electrical panels, see a sample installation diagram
• Pluggable screw terminals for easy wiring
• 0.5% accuracy nominal (see manual for details)
• True RMS power even with leading or lagging power factor and chopped or distorted waveforms
• Measure variable speed drive pumps and motors
• Safe CT's (current transformers), producing 0.333 VAC at rated current.
• Split core CTs for quick installation
• Solid core CTs are less expensive and prevent tampering
• Custom and standard Bus Bar sized CTs
• UL, cUL Listed - Designed and tested for safety and use throughout North America.

WattNode is a registered trademark of Continental Control Systems LLC.

Modbus Communication

• Protocol: Modbus RTU (binary)
• Baud Rates: 9,600 and 19,200
• Duplex: Half (two-wire plus common)
• Parity: N81 (no parity, eight data bits, one stop bit)
• Modbus Buffer: 256 bytes
• Response Time: 5 - 300 milliseconds

EIA RS-485 Interface:

• Driver Output Voltage (Open Circuit): ±6 V maximum
• Driver Output Voltage (54Ω load): ±1.5 V minimum
• Driver Output Current (54Ω load): ±60 mA typical
• Driver Output Rise Time (54Ω || 50pF load): 900nS typical
• Receiver Common-Mode Voltage Range: -7 V to +12 V maximum
• Receiver Sensitivity: ±200 mV
• Receiver Bus Load: 1/8 unit load

Certifications

• Emissions: FCC Part 15, Class B; EN 55022: 1994, Class B
• UL and cUL Listed (UL 61010-1)

Electrical

• Line powered
• FCC Class B
• Operating Voltage Range: -20% to +15% of nominal
• Power Line Frequency: 50/60 Hz
• CT Input: 0.333 VAC nominal, 0 - 0.5 VAC operating, 3 VAC maximum

Measurement Configurations

• Three phase: 4 wire
• Three phase: 3 wire

Accuracy

• 0.5% nominal (see manual for details)

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  Click on the image for a larger view.

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

Pricing information for all models and products

Model	VAC Phase to Neutral	VAC Phase to Phase	Electrical Service Types	Neutral Required	MSRP
WNC-3Y-208-MB	120	208-240	1 Phase 2 Wire 120V with neutral 1 Phase 3 Wire 120V/240V 3 Phase 4 Wire 120V/208V		$293
WNC-3Y-400-MB	230	400	1 Phase 2 Wire 230V with neutral 3 Phase 4 Wire 230V/400V		$328
WNC-3Y-480-MB	277	480	3 Phase 4 Wire 277V/480V		$328
WNC-3Y-600-MB	347	600	3 Phase 4 Wire 347V/600V		$354
WNC-3D-240-MB	N/A	208-240	1 Phase 2 Wire 208V (No neutral) 1 Phase 2 Wire 240V (No neutral) 1 Phase 3 Wire 120V/240V 3 Phase 3 Wire 208V (No neutral) 3 Phase 4 Wire 120V/208V		$328
WNC-3D-400-MB	N/A	400	3 Phase 3 Wire 400V (No neutral) 3 Phase 4 Wire 230V/400V		$354
WNC-3D-480-MB	N/A	400-480	3 Phase 3 Wire 480V (No neutral) 3 Phase 4 Wire 277V/480V		$354

List prices for 1 piece quantities. Call for pricing on larger quantities.

Prices effective May 1, 2009. Prices subject to change without notice.

Datasheet, Manual, XIF File, and Application Notes

• Datasheet (PDF)
• Manual (PDF)
• Quick Install Guide (PDF)
• Engineering Specifications (DOC)
• Application Notes
• Register List (XLS)
• Tridium JACE Modbus (Jar File)

Updates

The WattNode Modbus production firmware version is periodically updated. The firmware cannot be field upgraded, so the WattNode 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.

See WNC series WattNode Modbus Releases for the full list of versions.

Options

• Option EP - Factory configure the WattNode to default to even parity (E81). This can be field configured using the ParityMode register.
• Option 19K - Factory preconfigure the baud rate DIP switch 8 to the 19,200 baud setting (ON).
• Option 38K - Factory configure the WattNode to default to 38,400 baud instead of using the DIP switch selection (9,600 or 19,200 baud). This can be field configured using the Baud register.
• Option TCP-RTU - Configure the WattNode to default to the TCP-RTU protocol option (can also be set or cleared with the ModbusMode register) for use with RS-485 to Ethernet gateways (serial device adapters). This can be field configured using the ModbusMode register.
• Option CT=xxx - Pre-assign xxx as the CtAmps value. This can be field configured using the CtAmps register.
• Option CT=xxx/yyy/zzz - Pre-assign xxx as the CtAmpsA, yyy as the CtAmpsB, and zzz as the CtAmpsC values. This can be field configured using the CtAmpsA, CtAmpsB, and CtAmpsC registers.
• Option AD=xxx - Factory preconfigure the address DIP switches (1-7) to the specified address.

Contact the factory about the following special options:

• Option 232 - Provide RS-232 I/O in place of RS485.
• Option TTL - Provide 5V TTL UART I/O in place of RS485.