The WattNode® Module for Modbus® is a kilowatt hour (kWh) energy and power meter with ANSI C12.1 and ANSI C12.20 class 0.5 accuracy. Designed for easy customization for nearly any application or type of equipment, the WattNode Module provides bidirectional energy and power readings via an RS-485 port using Modbus RTU communications. The WND-M1-MB meter measures 1, 2, or 3 phases, in delta or wye services, from 120 to 600 Vac. It is packaged in a compact, DIN-rail mount enclosure. Current transformers are available in various opening sizes with ratings from 5 to 6,000 amps. The Module is instrument powered from 6-24 Vdc or from an isolated 12-24 Vac control transformer. The optional MDR-10-12 can power up to 12 WND-M1-MB meters.
- Supports floating-point and integer registers
- Active (real) power: watts, individual meter elements and sum of elements
- Reactive power: VARs, individual meter elements and sum of elements
- Power factor: individual meter elements and sum of elements
- Active (real) energy: kilowatt-hours (kWh), individual meter elements and sum of elements; net, positive, and negative
- Reactive energy: kVAR-hours, individual meter elements and sum of elements; net, positive, and negative
- AC line frequency (Hz)
- RMS voltage line-to-neutral: VAN, VBN, VCN
- RMS voltage line-to-line: VAB, VBC, VCA
- RMS current: CT1, CT2, CT3
- Demand: individual meter elements and sum of elements
- Peak demand sum: minimum and maximum
- Apparent power demand
Diagnostic LEDs provide a per-phase indication of line voltage and power (green flashing) and negative power (red flashing) to help troubleshoot connection problems, like reversed CTs. The WattNode Module for Modbus meter also has a red/yellow/green communication LED to indicate traffic, configuration problems, bus contention, and other conditions. See the manual for full descriptions.
WattNode® Module for Modbus® – Features
|Meets ANSI C12.1 and ANSI C12.20 Class 0.5 revenue metering standards|
|Small form factor for easy installation inside most electrical panels, see a sample
|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), output 0.333 Vac at rated current.|
|UL, cUL Listed – Designed and tested for safety and use throughout North America.|
|Assembled in USA, qualified under the Buy American provision in the American Recovery and Reinvestment Act of 2009 (ARRA).|
|Five year warranty|
|Compact, DIN-rail mount design|
|Instrument powered from 6-24 Vdc or a isolated 12-24 Vac source|
Differences between the RWND and WND
- RWND comes with a calibration certificate
- RWND requires that you specify a revenue-grade CT model when ordering the meter. This will appear on the meter’s calibration certificate.
- Note: the CT amps are not locked on either model unless you order Option L.
The following accuracy specifications do not include errors caused by the current transformer accuracy or phase angle errors. “Rated current” is the current that generates a CT output voltage of 0.33333 Vac or equivalent milliamp output.
Unless otherwise noted, all accuracy specifications assume the following conditions:
- Line voltage: 100 to 690 Vac
- Power factor (PF): 0
- Frequency: 48 – 62 Hz
- Ambient Temperature: 23°C ± 5°C
- CT Current: 1% – 100% of rated current
|Parameter||Test Conditions||Typ Max||Unit|
|EnergySum, Energy1, 2, 3(1) (active energy)||elapsed time(2) >= 10 s||±0.2 ±0.5||%|
|PowerSum, Power1, 2, 3 (active power)||averaging >= 1 s||±0.3 ±0.5||%|
|VoltA, B, C, VoltAB, BC, CA (RMS voltage)||averaging >= 1 s||±0.3 ±0.5||%|
|Current1, 2, 3 (RMS current)||averaging >= 1 s||±0.2 ±0.5||%|
|Freq (frequency)||averaging >= 1 s||±0.05 ±0.2||%|
|PowerFactor1, 2, 3||averaging >= 1 s, PF > 0.5||±0.5 ±1.0||%|
|EnergyReacSum, EnergyReac1, 2, 3 (reactive energy)||elapsed time(2) >= 10 s, PF < 0.9||±0.6 ±1.5||%|
|PowerReacSum, PowerReac1, 2, 3 (reactive power)||averaging >= 1 s, PF < 0.9||±0.6 ±2.0||%|
|EnergyAppSum, EnergyApp1, 2, 3 (apparent energy)||elapsed time(2) >= 10 s||±0.3 ±0.5||%|
|PowerAppSum, PowerApp1, 2, 3 (apparent power)||averaging >= 1 s||±0.3 ±0.5||%|
(1) Note: when parameters are written like Energy1, 2, 3, this means Energy1, Energy2, and Energy3.
(2) Note: This indicates that energy accuracy should be evaluated over a period of 10 seconds or longer.
- Meet the ANSI C12.1-2008 standard for revenue metering when used with class 0.6 or better current transformers.
- Meet the ANSI C12.20-2010 standard for revenue metering when used with class 0.3 or better current transformers.
- Update Rate: 0.1 second. Internally, all measurements are performed at this rate, except the energy registers, which are updated every 1.0 second.
- Start-Up Time: Energy measurement starts ~100 milliseconds after the supply voltage is applied. Modbus communication is enabled ~300 milliseconds after the supply is applied; at this time, all the registers will report valid data, such as power, voltage, current, etc.
- Default CT Phase Angle Correction: 0.0 degrees.
- Nominal Power Supply Voltage: 6 to 24 Vdc or isolated 12 to 24 Vac source
- Power Supply Minimum Operating Voltage: 6 Vdc or 10 Vac
- Power Supply Absolute Maximum Voltage: 40 Vdc or 30 Vac
- Power Supply Watts: typical 0.6 W, maximum 1.0 W
- Power Supply Current (milliamps):
|DC Supply Volts||Typical (mA)||Maximum (mA)|
- Line Frequency: 45 to 65 Hz
- Nominal Line-to-Neutral Vac: 90 to 347 Vac
- Nominal Line-to-Line Vac: 120 to 600 Vac
- Measurement Over-Voltage Limit: 720 Vac
- Over-Current Limit: 200% of rated current. Exceeding 200% of rated current will not harm the meter, but the current and power will not be measured accurately.
- Maximum Surge: EN 61000-4-5: 2kV, ANSI C12.1 combination wave: 6kV, 1.2/50 μs – 8/20 μs
- Line Voltage Power Consumption: The line voltage sensing circuitry draws 0.006 watts per phase at 120 Vac, increasing to 0.150 watts per phase at 600 Vac.
- Real Power (50-60 Hz): <= 0.2 watts
- Power Factor: ~1.0
- Rated VA: 25 VA at 720 Vac, 50 Hz. The Rated VA is the maximum at 115% of nominal Vac at 50 Hz.
- Measurement Category: The line voltage measurement terminals on the meter are rated for CAT III, 600 Vac. Measurement Category III is for measurements performed in the building installation. Examples are measurements on distribution boards, bus-bars, branch circuits, plug loads, and permanently connected equipment such as motors, boilers and heaters.
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
EIA RS-485 Interface
- RS-485 Output Isolation: 4500 Vac RMS
- Driver Output:
- Voltage (Open Circuit): ±6 Vdc maximum
- Voltage (54 Ω load): ±1.5 Vdc minimum
- Current (54 Ω load): ±60 mA typical
- Rise Time (54 Ω || 50 pF load): 900 nS typical
- Common-Mode Range: -7 Vdc to +12 Vdc max
- Sensitivity: ±200 mV
- Bus Load: 1/8 unit load (up to 64 meters)
- Failsafe Modes: bus open, shorted, and idle
- UL: UL Listed 2808
- UL / IEC 61010-1, 3rd Edition
- CAN/CSA-C22.2 No. 61010-1-12, 3rd Edition
- FCC: Class B, FCC Part 15, radiated and conducted emissions
- CE: 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) No Degradation
- Electrical Fast Transient / Burst: EN/IEC 61000-4-4: (A) No Degradation
- Surge Immunity: EN/IEC 61000-4-5: (A) No Degradation
- Conducted RF Immunity: EN/IEC 61000-4-6: (A) No Degradation
- Power Frequency H-field Immunity: EN/IEC 61000-4-8: (A) No Degradation
- Voltage Dips, Interrupts: EN/IEC 61000-4-11: (B) Self-Recovering
- RoHS Compliant
- Operating Temperature: –40°F to +176°F (–40°C to +80°C)
- Operating Humidity: non-condensing, 5 to 90% relative humidity (RH) up to 104°F (40°C), decreasing linearly to 50% RH at 131°F (55°C)
- Operating Altitude: Up to 9842 ft (3000 m)
- 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 if mounted inside an electrical enclosure (Hammond Mfg., Type EJ Series) rated NEMA 3R or 4 (IP 66)
- Enclosure: High impact, ABS/PC plastic
- Flame Resistance Rating: UL 94V-0, IEC FV-0
- Size: 19 in. × 3.68 in. × 1.15 in. (106.4 mm × 93.4 mm × 29.1 mm)
- Connectors: Euroblock pluggable terminal blocks
- Green: up to 12 AWG (2.5 mm2), 600 V
- Black: up to 12 AWG (2.5 mm2), 300 V
- Screw torque 3.5 lbf·in (4.08 kgf·cm)
- Weight: 4.7 oz (134 gm)
WattNode® Module for Modbus® – Model Part Numbers
|Model||Vac Line to Neutral||Vac Line to Line||Electrical Service Types||Neutral Required|
|120-347||208-600||L-N Vac is 120-347 L-L is 208-600||No|
|120-347||208-600||L-N Vac is 120-347 L-L is 208-600||No|
- Voltage Ranges listed in table are -20% to +15% of nominal. Operating Frequencies: 50/60 Hz
- Works either with or without a neutral connection.
- Add 10% to the indicated price for any option or valid combination of options. For a list of available options see the Modbus Module Options tab.
WattNode® Module for Modbus® – Downloads
These downloads apply to the following WattNode Module for Modbus models:
- WND-M1-MB – Standard model
- RWND-M1-MB – Ships with calibration certificate
- Brochure: WattNode Module for Modbus Brochure (PDF, 2 pages)
Manuals and Technical Documents
- Engineering Datasheet: WND-M1-MB Datasheet (PDF, 7 pages)
- Installation Manual: WND-M1-MB Installation Manual (PDF, 16 pages)
- Reference Manual: WND-M1-MB Reference Manual (PDF, 69 pages)
- Modbus Register List: WND-M1-MB Modbus Register List (v.1033) (Excel, 79k)
- Manual Supplement: MS-34 WND-M1-MB Opt HW (PDF, 1 page)
The WattNode Meter Module production firmware version is periodically updated. In most cases, updating meter firmware is not necessary unless you are experiencing problems or need a new feature. The Meter Module supports both field upgrades and factory firmware updates. There is a nominal charge for factory firmware updates unless they are needed to fix a bug under warranty.
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® Module for Modbus – Options
The WattNode® Module Modbus® and WattNode Revenue Module Modbus meter is available with several factory options at an additional charge. See the manual for more information and details about the registers mentioned below. To specify options, add the option codes you want as a string to the base part number. For example: WND-M1-MB Opt 19K,AD=1,EP specifies a meter configured for 19.2 kB, address 1, and even parity.
These options apply to the following two families of WattNode meters for the Modbus protocol:
- WattNode Module Modbus
- WattNode Revenue Module Modbus
Meter Element Configuration Options
These are used to configure the ConnectionType or MeterConfig registers.
Only one of the following two options may be specified for a particular meter.
- Option CTR=x – Set the ConnnectionType register to x (the default is 1). See the WND Meter Module Reference Guide for more information.
|Connection Type||Name||Meter Element Mapping||Service Types||Notes||Meter Config1||Meter Config2||Meter Config3|
|0||Custom||Custom||Any||May not be used with the CTR=x option||–||–||–|
|1||Wye||CT1-VAN CT2-VBN CT3-VCN||3-phase 4-wire wye||May also be used for 4-wire delta service||10||20||30|
|3-phase 3-wire delta||CT3 is not used. Works for grounded delta with any phase grounded.||90||50||0|
|3||Branch circuits||CT1-VAN CT2-VAN CT3-VAN||1-phase, 2-wire with neutral||Use for monitoring 1-3 neutral connected branch circuits||10||10||10|
|4||House and Inverter||CT1-VAN CT2-VBN CT3-VAB||See notes||1-phase, 3-wire with neutral for CT1 and CT2; 1-phase, 2-wire without neutral for CT3||10||20||40|
|5||Line to Line||CT1-VAB||1-phase, 2-wire (no neutral)||CT2 and CT3 are not used||40||0||0|
- Option MCR=xx/yy/zz – Set MeterConfig1 to xx, MeterConfig2 to yy, and MeterConfig3 to zz. See the WND Meter Module Reference Guide for more information
The mapping from current transformer inputs to line voltage inputs is controlled with the MeterConfig registers. There are one meter element and one configuration register for each current transformer. For each meter element (CT), you can select the line voltage to be associated with that CT from the following list:
- 0 = Disable meter element
- 10 = VAN (also called VA)
- 20 = VBN (also called VB)
- 30 = VCN (also called VC)
- 40 = VAB
- 50 = VBC
- 60 = VCA
- 70 = VBA (equal to -VAB)
- 80 = VCB (equal to -VBC)
- 90 = VAC (equal to -VCA)
The default settings for the MeterConfig registers follow. These match the behavior of the older WNB and WNC meters:
- MeterConfig1 = 10
- MeterConfig2 = 20
- MeterConfig3 = 30
Current Transformer Options
The following options are only for use with non-standard current transformers (CTs), such as milliamp output CTs or CTs with a full-scale output voltage other than 0.333 Vac. Most CCS CTs, including standard Accu-CTs, do not require any of the following options.
- R=xxx or R=xxx/yyy/zzz – Specify the burden resistance for all three phases or for each phase individually. This means a burden resistor is installed in the meter to allow use of a milliamp output CT. If this option is not specified or the value is 0, then there is no burden resistor installed in the meter and the meter must be used with 0.333 Vac CTs (internally burdened millivolt output CTs).
- V=xxx or V=xxx/yyy/zzz – Specify the full-scale CT output voltage for all three phases or for each phase individually. If this option is not specified, then 0.33333 Vac is the default value.
- MA – Specify that the meter is designed for 40mA output CTs. Equivalent to “Opt R=10,V=0.4”
The communications options are used to configure the Modbus address, baud rate, and other communications parameters.
Defaults: AD=1, BAUD=19200, no parity, eight data bits, one stop bit
- Option AD=xxx – This is the Modbus slave address. If not specified, the default address is 1.
- 9.6K – Set the baud rate to 9,600. This is a shorter version of “BAUD=9600”.
- 19K – Set the baud rate to 19,200. This is a shorter version of “BAUD=19200”.
- 38K – Set the baud rate to 38,400. This is a shorter version of “BAUD=38400”.
- BAUD=xxxxxx – Set the baud rate to xxxxxx, where xxxxxx may be 1200, 2400, 4800, 9600, 19200, 38400, 57600, 76800, or 115200. The default baud rate is 19200.
- EP – Enable even parity (the default is no parity)
- 8N2 – Select two stop bits. The default is one stop bit.
- T1 – Install a fixed (non-switchable) 120Ω burden resistor and two 1.2k Ω bias resistors (to Modbus common and 3.3V). By default, the meter module does not provide termination or biasing.
Cost Reduction Options
These options are normally only available if the Meter Module is ordered in high volume for OEM applications.
- NDL – No LEDs and no light pipes.
- 1PD – (Single-phase delta) Only populate components for one CT channel (CT1). On the voltage inputs, do not populate or use low-cost/low-accuracy components for the N and L3 (phase C) inputs. Use normal connectors.
- 1PY – (Single-phase wye) Only populate components for one CT channel (CT1). On the voltage inputs, do not populate or use low-cost/low-accuracy components for the L2 and L3 inputs. Use normal connectors.
- 1P – (Single-phase) Only populate components for one CT channel (CT1). On the voltage inputs, do not populate or use low-cost/low-accuracy components for the L3 inputs. Use normal connectors.
- WND-M0-MB – No enclosure (for embedded use)
- RWND-M0-MB – No enclosure, with calibration certificate
Warning: Hazardous Voltages – Only qualified personnel or licensed electricians should install the WattNode meter and current transformers.
Modbus is a registered trademark of Schneider Electric USA, Inc.