Continental Control Systems WattNode WND-WR-MB

Compatibility

Compatible with EpiSensor Edge over Modbus RTU

The WND-WR-MB is compatible with EpiSensor Edge over Modbus RTU on its RS-485 terminals, read through a ZMB-31 Modbus Interface or a Gateway serial port. Continental Control Systems publishes the complete register list with the one-based address convention, function codes 03 and 04, data types, units, scaling and the 32-bit word order.

WattNode Wide-Range for Modbus WND-WR-MB, firmware 1033 and later and hardware version 8 and later, using reference manual WND-WR-MB-Ref-1.02. Earlier WNC-series WattNode Modbus meters are not covered. Site check: read the float VoltAN at 1019 and 1020, low word first, and the integer VoltAN at 1214, and compare both with a handheld meter on the VA to VN terminals. Read-only monitoring: no writes to the CT, metering, passcode, energy reset or communication registers.

Connect it with

• Modbus Interface ZMB-3X From €399 ex VAT Configure
• Gateway ZGW-20 From €899 ex VAT Configure

Models

Specifications

Model

One model, WND-WR-MB, for every service from 100 to 600 Vac; all units are revenue grade, and a certificate of calibration is a separate item, WN-CAL-CERT. The reference manual covers firmware 1033 and later and hardware version 8 and later.^1, 2

Current inputs

Three inputs for external CTs with a 0.33333 Vac output at rated current (input impedance 23 kΩ, absolute maximum 5.0 Vac); 40 mA output CTs only with factory option MA or R. CT rated current is set per input from 0 to 30000 A. 1 A and 5 A output CTs must not be connected: CCS warns that they destroy the meter.^1, 2

Voltage inputs and supply

VN, VA, VB and VC; 100 to 600 Vac nominal, line-to-neutral 90 to 347 Vac and line-to-line 120 to 600 Vac; 690 Vac maximum; 45 to 65 Hz; measurement category CAT III 600 V. The meter is powered from VA and VB, minimum 85 Vac. PT ratio 0.05 to 300 for potential transformers.¹

Accuracy

Active energy ±0.5% maximum (±0.2% typical), active power, voltage and current ±0.5% maximum, excluding CT errors. Meets ANSI C12.1-2008 and ANSI C12.20-2010 class 0.5 without CT errors; as a system, ANSI C12.20 class 0.5 with class 0.2 or 0.3 CTs and ANSI C12.1 with class 0.6 CTs.¹

Modbus RTU

Half-duplex RS-485, two wires plus common, isolated 4500 Vac RMS. Address 1 to 63 by DIP switch or 1 to 247 by register; 9600 or 19200 baud by DIP switch 8, 1200 to 115200 baud by register; 8N1 by default, 8E1 and 8N2 optional. FC03, FC04, FC06, FC16 and FC17. Typical response 5 to 25 ms; 256-byte buffer.^1, 2

Bus loading and termination

1/8 unit load receiver, up to 256 WattNode meters on one subnet. DIP switch 7 switches an internal 120 Ω terminator; the meter has a failsafe receiver and no bias resistors (option T1 fits a fixed terminator and bias). Maximum bus length unterminated: 860 m (2822 ft) at 9600 baud, 430 m (1411 ft) at 19200, 215 m at 38400 and 70 m (230 ft) at 115200; terminated at both ends: 1220 m (4000 ft) up to 76800 baud and 990 m (3250 ft) at 115200.^1, 2

Approvals

UL Listed for the U.S. and Canada, file E359088, to UL/IEC 61010-1 3rd edition and CAN/CSA-C22.2 No. 61010-1-12; FCC Part 15 class B; CE to the Low Voltage and EMC directives, EN 61326-1:2013 industrial locations; RoHS.¹

Environment

Operating -40 to +80 °C; 5 to 90% relative humidity up to 40 °C, non-condensing, falling to 50% at 55 °C; altitude up to 3000 m; pollution degree 2; IP40. Indoor use, or outdoors inside an enclosure rated NEMA 3R or 4.¹

Housing

153 × 85.1 × 38.0 mm, 233 g, ABS/PC rated UL 94V-0. Pluggable terminal blocks for up to 2.5 mm² (12 AWG); two mounting holes 137 mm apart under the terminal blocks.¹

Interface

Documented measurements and integration boundaries for WattNode WND-WR-MB.

• CCS documents register numbers one-based and the wire address is one less: EnergySum is documented at 1001 and sent as 1000 (0x03E8). Modbus software that asks for register numbers takes 1001 as printed. The meter does not use the 3xxxx or 4xxxx prefixes, and FC03 and FC04 read any register.
• 32-bit floats and 32-bit integers occupy two registers and are little-endian: the first, lower-addressed register holds the least significant 16 bits. Clients call this float or long swapped; Tridium JACE calls it byte order 1032. Read both registers in one request so the value cannot change between them.
• Float voltages in V: VoltAvgLN 1017, VoltAN 1019, VoltBN 1021, VoltCN 1023, VoltAvgLL 1025, VoltAB 1027, VoltBC 1029 and VoltCA 1031, two registers each. Frequency Freq at 1033 in Hz. A voltage channel below 20% of the nominal voltage, or of the highest measured voltage if that is higher, is treated as inactive and reads zero.
• Float active power in W: PowerSum 1009 and Power1 to Power3 at 1011, 1013 and 1015, averaged over 5 seconds by default. PowerFastSum 1037 and PowerFast1 to PowerFast3 at 1039 to 1043 update every 100 ms with no averaging. Reactive power PowerReacSum 1147 (VAR) and apparent power PowerAppSum 1155 (VA), each followed by elements 1 to 3.
• Float current in A: Current1 to Current3 at 1163, 1165 and 1167, unsigned by default. Power factor PowerFactorAvg at 1139 and elements 1 to 3 at 1141 to 1145; it includes harmonics and is negative when the element's power is negative.
• Float energy in kWh: EnergySum 1001 (net), EnergyPosSum 1003, EnergySumNR 1005, EnergyPosSumNR 1007 and EnergyNegSum 1113, with per-element registers from 1101. Reactive energy EnergyReacSum 1123 (kVARh) and apparent energy EnergyAppSum 1131 (kVAh). Above 100,000 kWh a float's resolution becomes coarser than 0.1 kWh.
• Integer energy, 32-bit signed, low word first, in 0.1 kWh: EnergySum 1201, EnergyPosSum 1203, EnergySumNR 1205, EnergyPosSumNR 1207, EnergyNegSum 1313 and EnergyNegSumNR 1315; per element from 1301. CCS suggests these for energy because their resolution stays at 0.1 kWh. The NR (non-resettable) registers cannot be zeroed or preset.
• Negative energy registers report a positive number: 1000 kWh of exported energy reads 1000 in EnergyNegSum. Power is negative when the element generates or its CT is reversed.
• Integer measurements are single 16-bit signed registers: VoltAN to VoltCA at 1214 to 1220 and VoltAvgLN at 1213 in 0.1 V; Freq at 1221 in 0.1 Hz; power factor at 1339 to 1342 in 0.01.
• Integer power, reactive power, apparent power and demand (1209 to 1212, 1343 to 1350, 1354 to 1360) are multiplied by PowerIntScale at 1609, which reads the factor in use (1, 10, 100, 1000 or 10000) when set to automatic. CCS's example: PowerSum 2500 with PowerIntScale 100 is 250,000 W.
• Integer current at 1351 to 1353 is scaled amps: current = register × CtAmpsX / CurrentIntScale, with CtAmps1 to CtAmps3 at 1604 to 1606 and CurrentIntScale at 1622 (default 20000). CCS's example: 5000 with 200 A CTs is 50.00 A. The float current registers need no scaling.
• Demand in W: DemandSum 1169, DemandSumMin 1171, DemandSumMax 1173, DemandAppSum 1175 and Demand1 to Demand3 at 1177 to 1181, over a 15-minute period by default (DemPerMins at 1610). Demand reads zero until one full interval has passed after power-up.
• Identity and health: SerialNumber at 1701 (32-bit), Model at 1707 (510), firmware Version at 1708, ErrorStatus1 at 1716 (0 = no errors) and CtStatus1 to CtStatus3 at 1760 to 1762 when disconnected-CT detection is enabled. Dummy at 0001 always returns 0.
• SunSpec models 1, 203, 213 and 64080 start at 40001 one-based (40000 on the wire) and are big-endian, the opposite word order to the CCS registers. Use one register set per Edge configuration and keep its word order.
• Configuration and command registers from 1601 to 1659 (passcode, CT amps, CT directions, averaging, scaling, ZeroEnergy, ZeroDemand, meter element configuration, PT ratio, address, baud rate and parity) accept FC06 and FC16 writes. Never write them from a monitoring configuration.

Setup

1. Identify the meter and its options

   Check that the label reads WND-WR-MB and note any options printed on it, such as EP, 8N2, AD= or a baud rate, which change the communication settings. Record the rated current of each CT and which voltage phase it sits on.

2. Read the DIP switch

   DIP switches 1 to 6 set the address from 1 to 63 (values 1, 2, 4, 8, 16 and 32), switch 7 the internal terminator and switch 8 the baud rate: down for 9600, up for 19200. The meter ships set to address 0, which is invalid: the Com LED lights solid red and the meter does not answer.

3. Wire the RS-485 bus

   Connect A-, B+ and the C common in a daisy chain, never home runs. Earth the shield or common at the Gateway end only. A bus longer than 860 m at 9600 baud or 430 m at 19200 needs 120 Ω at both ends, using DIP switch 7 on the last meter.

4. Make the first reads

   Read Model at 1707, one register: it returns 510. Then read the float VoltAN at 1019 and 1020 low word first, as in the worked read below, and the integer VoltAN at 1214 in 0.1 V. Both should agree with each other and with a handheld meter on VA to VN.

5. Check the CT configuration

   Read CtAmps1 to CtAmps3 at 1604 to 1606 and compare them with the CTs fitted; the factory value is 5. A wrong value scales every current, power and energy reading, and correcting it belongs to the meter's commissioning, not to Edge's read-only poll. Check that ErrorStatus1 at 1716 reads 0 and that Power1 to Power3 are positive on a consuming load.

6. Add the points you need

   Add the float power, current and voltage registers, and the 32-bit integer energy registers in 0.1 kWh for counters that keep their resolution. Keep the configuration, reset and communication registers out of the polling configuration.

Common questions

Is the WattNode address 1019 or 1018?

Both, depending on where you type it. CCS documents registers one-based, so a Modbus tool that asks for register numbers takes 1019. On the wire the address is one less, 1018 (03FAh). CCS's own example: EnergySum at 1001 goes on the bus as 1000, 0x03E8.¹

Why are my WattNode float values huge, tiny or invalid?

The CCS registers send the least significant 16 bits first. Set the client to the swapped or reversed float and long order (byte order 1032 on a Tridium JACE) and read both registers in one request. The SunSpec registers from 40001 are the other way round, most significant word first.¹

How do I convert the WattNode integer current to amps?

Multiply by the CT rated current and divide by CurrentIntScale: current = Current1 × CtAmps1 / CurrentIntScale. With 200 A CTs and the default CurrentIntScale of 20000, a reading of 5000 is 50.00 A. The float current registers at 1163 to 1167 are already in amps.¹

Which energy register should I use for kWh?

For energy drawn from the supply, EnergyPosSum: the float at 1003 in kWh or the 32-bit integer at 1203 in 0.1 kWh, low word first. CCS suggests the integer for energy, because a float's resolution becomes coarser than 0.1 kWh above 100,000 kWh. EnergySumNR and EnergyPosSumNR cannot be reset.¹

Can the WattNode be used with 5 A CTs?

No. The WND-WR-MB takes CTs with a 0.333 Vac output at rated current, or 40 mA output CTs on a meter ordered with option MA or R. CCS warns that 1 A or 5 A output CTs, usually labelled with a ratio such as 100:5, destroy the meter.^1, 2

Does the WattNode Modbus have Modbus TCP?

No. The WND-WR-MB has an RS-485 port running Modbus RTU only. CCS notes that earlier WattNode Modbus firmware carried Modbus TCP framing over RS-485 and that this was removed. Edge reads it through a ZMB-31 or a Gateway serial port.¹

The WattNode does not answer and the Com LED is solid red. What is wrong?

The DIP switch is at address 0, which is how the meter ships and which is invalid. Set switches 1 to 6 to a unique address from 1 to 63. A Com LED that flashes red for one second instead points to a CRC or framing error: check the baud rate, parity and the A- and B+ wiring.¹