Carlo Gavazzi WM50

Panel-mounted power analyser

The WM50 measures a three-phase main line through 5 A current transformers and up to 96 outgoing channels through as many as eight 12-channel TCD12 split-core sensors on its built-in MABC bus. Single channels can be grouped into up to 48 two-phase or three-phase loads. The communication port comes from a plug-in module: MC485232 for Modbus RTU on RS-485 or MCETH for Modbus TCP. Carlo Gavazzi's protocol gives each channel a fixed 14-register block from C200h and each load a 24-register block from C760h, with floats sent low word first and channel energy as a 32-bit Wh counter that Edge can read.

Carlo Gavazzi WM50
  • Modbus RTU
  • Modbus TCP

Panel-mounted power analyser

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Compatibility

Compatible with EpiSensor Edge over Modbus RTU or Modbus TCP

The WM50 is compatible with EpiSensor Edge through its plug-in communication module: Modbus RTU on the MC485232 RS-485 port, read through a ZMB-31 Modbus Interface or a Gateway serial port, and Modbus TCP on the MCETH Ethernet port. Carlo Gavazzi publishes the register map with physical and Modicon addresses, data types and word order for the main line, every channel and every load.

WM50 AV5 3 H BC with TCD12 sensors and an MC485232 or MCETH module, using the WM50 communication protocol rev. 1.0.0 of 27 September 2017. A WM50 without a communication module has no Edge route. Site check: read the identification code at 000Bh, then compare channel 1 current and energy with UCS or the display. Main line energy counters are 64-bit and outside what Edge's Modbus client reads. Read-only monitoring: no writes to the reset, alarm or configuration registers.

Connect it with

Route into Edge

For a WM50 in a distribution board where a wireless link avoids running a data cable back to the Gateway

  • Modbus
  • Wireless
  • Edge
  • Platforms
Panel-mounted power analyser
Interface
Gateway
Edge
Output
WM50MC485232 module RS-485 terminals A-, B+ and GND
ZMB-31Modbus RTU to the EpiSensor wireless network
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeModbus client + register map
Customer platformMQTT · API · files
Modbus RTU · RS-485
EpiSensor wireless
Runs locally
Optional onward data
Wire the RS-485 pair and GND from the MC485232 to the ZMB-31 and match the WM50's address, baud rate and parity. With 96 channels the poll is long, so read only the channels and loads in use, in blocks. The customer-platform output is optional; Edge remains the local system of record.

When the Gateway sits near the WM50, or several analysers share one wired bus

  • Modbus
  • Edge
  • Platforms
Panel-mounted power analyser
Interface
Gateway
Edge
Output
WM50MC485232 module RS-485 terminals A-, B+ and GND
Isolated serial interfaceApproved RS-485-to-host adapter
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeEdge Modbus client
Customer platformMQTT · API · files
Modbus RTU · RS-485
Isolated serial
Runs locally
Optional onward data
Terminate the last device with a jumper between B+ and T, as the module manual describes, and use the same baud rate (9.6, 19.2, 38.4 or 115.2 kbps) and parity in the Edge serial client. At 115.2 kbps Carlo Gavazzi gives a typical answering time below 10 ms. The customer-platform output is optional; Edge remains the local system of record.

When the WM50 carries the MCETH Ethernet module

  • Modbus
  • Edge
  • Platforms
Panel-mounted power analyser
Interface
Gateway
Edge
Output
WM50MCETH module RJ45 port
Protected EthernetSegmented LAN
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeEdge Modbus TCP client
Customer platformMQTT · API · files
Modbus TCP
Protected Ethernet
Runs locally
Optional onward data
Set the IP address, subnet mask, gateway and TCP/IP port on the WM50 and use the same port in Edge. The datasheet gives no default port, so read it from the communication menu. The module accepts up to 5 simultaneous Modbus clients. The customer-platform output is optional; Edge remains the local system of record.

Models

Download
ModelsInterfaceRoute into Edge
WM50 AV5 3 H BC with MC485232Main unit with pre-assembled MABC module for up to eight TCD12 sensors; MC485232 module with RS-485 or RS-232 Modbus RTU (alternative ports)Read the main line, channel and load blocks on the serial path. Identification code 99 (0x0063) at 000Bh.
WM50 AV5 3 H BC with MCETHThe same main unit with the MCETH module: RJ45, Modbus TCP, up to 5 clientsRead the same addresses over Modbus TCP from the Gateway.
TCD12 and TCD12WS12-channel split-core current sensors, 10 A base, 32 A rated and 65 A maximum per channel, powered from the TCD bus and joined with TCD12WS cablesNo port of their own. Each TCD12 channel appears in the WM50's channel blocks.

Specifications

The WM50 suits data centre power distribution units and other boards with many outgoing breakers, where one analyser measures the incomer and every branch circuit. The main line is class 0.5S for active energy; each TCD12 channel is class 2. Up to 96 channels and 48 grouped loads are available over Modbus.2

Order code
WM50 AV5 3 H BC main unit; TCD12 current sensors, TCD12WS cables and the MC485232 or MCETH communication module are separate part numbers.2
Main line inputs
Direct voltage connection, 120 to 277 V L-N, 208 to 480 V L-L, 50/60 Hz; current through CTs, 5 A rated, 6 A maximum, CT ratio 1 to 2000.2
Channels
Up to eight TCD12 sensors, 12 channels each, 96 channels in total; per channel 10 A base current, 32 A rated primary and 65 A maximum.2
Accuracy
Main line active energy class 0.5S (EN 62053-22) and reactive energy class 2 (EN 62053-23); channel and load active energy class 2 (EN 62053-21).2
RS-485 (MC485232)
Modbus RTU, address 1 to 247, 9.6, 19.2, 38.4 or 115.2 kbps, no, odd or even parity; up to 160 devices at 1/5 unit load; 2-wire, up to 1000 m.23
Ethernet (MCETH)
RJ45, 10Base-T and 100Base-TX, up to 100 m; Modbus TCP with up to 5 simultaneous clients.2
Housing
Panel mounting; front IP65, NEMA 4x and NEMA 12; terminals IP20. TCD12 front IP50.2
Environment
Operating -25 to +40 °C, storage -30 to +70 °C, relative humidity below 90% non-condensing at 40 °C, for the main unit and the TCD12.2

Interface

Documented measurements and integration boundaries for WM50.

  • Addresses are physical word addresses sent in the frame: channel 1 current is Modicon 349665 and physical C200h, and goes on the wire as 0xC200. FC03 and FC04 return the same values.
  • Floats are IEEE 754 single precision in two registers with the low word first: the first byte on the wire is bits 15 to 8 and the third is bits 31 to 24. The protocol states low word first for UINT64 too, but gives no separate rule for the UINT32 energy counters, so confirm their word order against UCS with the first energy read.
  • Channel n (1 to 96) block starts at C200h + 14 x (n - 1): current [A] at +0, active power [W] +2, reactive power [var] +4, apparent power [VA] +6, power factor +8 and THD current [%] +10 as floats, and active energy [Wh+] at +12 as UINT32. Channel 1 energy is C20Ch and channel 96 energy C73Eh.
  • Load m (1 to 48, a group of two-phase or three-phase channels) block starts at C760h + 24 x (m - 1): system voltage +0, current L1, L2, L3 +2, +4, +6, active power +8, apparent power +10, reactive power +12, power factor +14, THD current L1 to L3 +16 to +20 as floats, and active energy [Wh+] at +22 as UINT32. Load 48 energy is CBDEh. Current L3 and THD L3 read only with a third phase configured.
  • Channel voltage reference at C100h to C15Fh (UINT16: 1 L1, 2 L2, 3 L3) and the line-neutral voltages Vl1n, Vl2n, Vl3n at C750h, C752h, C754h as floats.
  • Main line floats from the CT inputs: V L1-N to L3-N at 0050h to 0054h, V L1-L2 to L3-L1 at 0058h to 005Ch, A L1 to L3 at 0060h to 0064h, A N 0066h, W L1 to L3 0068h to 006Ch and W system 006Eh, VA from 0070h, var from 0078h, PF from 0080h, Hz at 0088h and total THD from 00A0h.
  • Main line energy counters from 0500h (Total kWh+, kvarh+, kWh-, kvarh-, partial and tariff counters) are UINT64 in four registers, in Wh or varh. Edge's Modbus client does not read 64-bit values; the channel and load energies are the 32-bit Wh counters to use.
  • The channel and load Wh+ counters are UINT32, so they roll over after 4 294 967 295 Wh (about 4 294 967 kWh). Treat a drop to a small value as a roll-over or a reset.
  • Minimum, maximum and demand values for channels and loads from CC00h exist only for the one variable selected in UCS for alarms and the database, each with a UNIX timestamp. The configurable map at D600h to D7F2h holds variables chosen in UCS.
  • Identity: base firmware at 0000h (high byte A for WM50AV5), communication module firmware at 0001h, identification code at 000Bh (99) and the serial number in the identity table.
  • Write registers: the reset commands from 3500h (energy counters), alarm commands and every configuration register. Keep them out of a monitoring poll.

Assessment

WM50 AV5 3 H BC with TCD12 sensors and an MC485232 or MCETH module, using the WM50 communication protocol rev. 1.0.0 of 27 September 2017. Read-only monitoring: no writes to the reset, alarm or configuration registers.

InteroperabilitySupported with conditions
Channel and load blocks have fixed addresses, float word order and 32-bit Wh counters that Edge reads; main line energy is UINT64 only.1
AccuracySupported with conditions
Main line active energy is class 0.5S, but channel and load energy through the TCD12 sensors is class 2.2
SecurityNot yet assessed
The protocol defines writable reset and configuration registers on the same Modbus port as the measurements.1
ReliabilitySupported with conditions
The protocol gives a 1000 ms maximum answering time, retry guidance and exception codes; the TCD12 is stated with a minimum 15-year MTBF/MTTF.12
RuggednessSupported with conditions
Front IP65, terminals IP20 and a TCD12 front of IP50 suit a distribution board, but the operating range stops at +40 °C.2
ScalabilityWell supported
One WM50 covers up to 96 channels and 48 loads with fixed block strides, and the RS-485 module runs at up to 115.2 kbps.12
LifecycleNot yet assessed
The datasheet is dated 01/12/2020 and the protocol is the first release, rev. 1.0.0.12

Setup

First read: channel 1 current and energy

Carlo Gavazzi's WM50 communication protocol rev. 1.0.0 (27 September 2017), section 2.1.2, gives channel 1 current at physical address C200h (Modicon 349665) as an IEEE 754 float and channel 1 active energy at C20Ch as UINT32 in Wh. Section 4.4 sends floats and UINT64 low word first and states no separate rule for UINT32, so the energy decode below assumes the same order. Use this as the starting point and compare the results with UCS or the display.

Identity read
01 04 00 0B 00 01 40 08: Modbus address 1, FC04, address 0x000B, one register. Synthetic response 01 04 02 00 63 F9 19 gives 0x0063 = 99, a WM50.
Request
01 04 C2 00 00 02 4C 73: Modbus address 1, FC04, address 0xC200 (channel 1 current), two registers, RTU CRC. Over Modbus TCP the same function, address and length go to the port set on the MCETH module.
Address convention
The physical address is the zero-based word address in the frame: send 0xC200 (49664). A client that numbers input registers from one shows it as 349665. Channel n starts 14 registers later per channel, so channel 2 current is 0xC20E.
Synthetic response
01 04 04 00 00 41 48 CB E2: four data bytes, low word 00 00 first, then high word 41 48. Swapped to 0x41480000 the float is 12.5 A.
Energy read
01 04 C2 0C 00 02 8C 70 reads channel 1 active energy at 0xC20C. Synthetic response 01 04 04 D6 87 00 12 F3 E8 has low word 0xD687 first and high word 0x0012, so, low word first, 0x0012 x 65536 + 0xD687 = 1234567 Wh, which is 1234.567 kWh. If UCS shows a different total, try the high word first before adding more channels.
Acceptance
Keep each point when it agrees with channel 1 in UCS or on the display. If it does not, check the word order, the channel numbering and the Modbus address before adding more channels.

Acceptance: The response bytes are a synthetic decoder check, not a captured analyser reply. A real reply must agree with UCS or the display before further channels and loads are enabled.

  1. Check the communication module

    Look at the back of the WM50 for an MC485232 or MCETH module. The MABC module is the TCD12 bus, not a communication port for Edge.

  2. Match the port settings

    For RS-485, read the address, baud rate and parity from the communication menu and enter the same values in Edge. For Ethernet, read the IP address and the TCP/IP port.

  3. List the channels in use

    Use UCS or the display to note which channels carry single-phase circuits and which are grouped into loads, and which voltage reference each channel uses (C100h onwards). Poll only those blocks.

  4. Read channel 1 first

    Read the identification code and channel 1 with the example below, then compare current and energy with UCS or the display. Add further channels by stepping 14 registers per channel.

  5. Keep energy to the 32-bit counters

    Use the channel and load Wh+ counters for energy. The main line counters from 0500h are 64-bit and Edge's Modbus client does not read them.

Common questions

How do I find the registers for channel 37?
Each channel has a 14-register block from C200h. Channel n starts at C200h + 14 x (n - 1), so channel 37 starts at C200h + 504 = C3F8h, with its Wh+ counter 12 registers later at C404h. Loads use 24-register blocks from C760h in the same way.1
Why do the channel minimum and maximum registers stay empty?
Carlo Gavazzi computes minimum, maximum and average values for channels and loads only for the one variable selected in UCS for alarms and the database. Select the variable in UCS first, or read the instantaneous blocks and let Edge keep the history.1
Is a branch channel as accurate as the main line?
No. The datasheet gives class 0.5S for main line active energy through CTs and class 2 for channel and load active energy through the TCD12 sensors. Use the main line for the incomer total and the channels for allocation.2

Sources

  1. WM50 communication protocol, user version rev. 1.0.0 (27 September 2017) (opens in a new tab) (PDF) Carlo Gavazzi
  2. WM50 multichannel power analyzer datasheet (WM50 DS ENG, 01/12/2020), main unit, TCD12 sensors, modules and order code (opens in a new tab) (PDF) Carlo Gavazzi
  3. WM series accessory and communication modules instruction manual (WMModules IM), wiring and termination (opens in a new tab) (PDF) Carlo Gavazzi

Further reading

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