socomec Continental Control Systems MCM MB Series User manual

www.ctlsys.com
Multi-CirCuit Meter (MCM)
Modbus®rtu, Modbus®tCP
Electric Power Meter - Installation Guide
Models: MCMxx-y-MB-zzzz, MCMxx-y-MBT-zzzz

Page 2 of 27 MCM-Inst-1.10
Contents
1 Precautions...............................................................................................................................................3
1.1 Symbols............................................................................................................................................3
1.2 Terminology......................................................................................................................................3
2 Overview ...................................................................................................................................................4
2.1 Model Number Scheme.................................................................................................................... 4
2.2 Multi-Circuit Metering .......................................................................................................................5
2.3 Additional Literature .........................................................................................................................6
3 Installation ................................................................................................................................................7
3.1 Installation Record............................................................................................................................ 8
3.2 Electrical Service or Load Types...................................................................................................... 9
3.3 Installation Checklist....................................................................................................................... 13
3.4 Mounting......................................................................................................................................... 13
3.5 Line Voltage Connections...............................................................................................................14
3.6 Current Transformer Connections..................................................................................................15
3.7 Modbus RTU (RS-485) Communication.........................................................................................16
3.8 Modbus TCP (Ethernet) Communication........................................................................................ 18
4 Operation ................................................................................................................................................23
4.1 Initial Configuration......................................................................................................................... 23
4.2 Power Status LEDs........................................................................................................................23
4.3 Modbus Communication LED......................................................................................................... 24
4.4 Monitoring.......................................................................................................................................24
4.5 Maintenance and Repair................................................................................................................24
5 Specifications.........................................................................................................................................25
5.1 Measurement .................................................................................................................................25
5.2 Electrical.........................................................................................................................................25
5.3 EIA RS-485 Interface...................................................................................................................... 26
5.4 Ethernet Interface...........................................................................................................................26
5.5 Certifications...................................................................................................................................26
5.6 Environmental ................................................................................................................................26
5.7 Mechanical.....................................................................................................................................26
5.8 FCC Information.............................................................................................................................26
5.9 Warranty.........................................................................................................................................27
5.10 Limitation of Liability.......................................................................................................................27

MCM-Inst-1.10 Page 3 of 27
1 Precautions
●Only licensed electricians or qualified personnel should install the MCM. The mains voltages of
100 to 600 Vac can be lethal!
●Follow all applicable local and national electrical and safety codes.
●The terminal block screws are not insulated. Do not contact metal tools to the screw terminals if
the circuit is live!
●Verify that circuit voltages and currents are within the proper range for the MCM model voltage
group.
●Use only UL Listed or Recognized current transformers (CTs). Depending on the meter options,
you may use either CTs with built-in burden resistors that generate 0.333 Vac (333 millivolts AC) at
rated current or milliamp output CTs that generate 40 mA at rated current. Do not use 1 amp or 5
amp output CTs: they will destroy the meter and may create a shock hazard.
●If your MCM model does not include a circuit breaker or fuses, then protect the line voltage
conductors supplying the MCM with fuses or circuit breakers. See 3.5.1 below.
●Disconnect equipment from HAZARDOUS LIVE voltages before access.
●If the meter is not installed correctly, the safety protections may be impaired.
●Torque all screws as specified on the information label on the inside of the enclosure door.
1.1 Symbols
Read, understand, and follow all instructions including warnings
and precautions before installing and using the product
Potential shock hazard from dangerous high voltage
Earth ground
UL Listed mark for the USA and Canada. It is located on the UL
508A label inside the enclosure and applies to the entire MCM.
The UL Recognized mark for the USA and Canada appears on
the MCM cards and some accessories.
1.2 Terminology
current sensor (or current transformer or CT): the terms current sensor and current transformer
(CT) are used interchangeably in this guide. They refer to devices that measureAC current and
output a millivolt signal representation of the current. The MCM may also support milliamp output
current transformers when ordered with the correct option.
meter element (or element): a meter element combines a voltage signal with a current signal to
measure and report AC power and energy, as well as additional parameters of interest. Each meter
element accepts one CT input. There are three meter elements in each submeter block. See 2.2
Multi-Circuit Metering for more details.
Modbus RTU: a version of the Modbus protocol primarily used over RS-485 (EIA-485) links.
Modbus TCP: a version of the Modbus protocol used over Ethernet TCP/IP networks.
primary SMB: the first submeter block in an MCM system, with a Modbus address offset of 0 relative
to the address assigned with the DIP switches or using Modbus Address register.
submeter block (SMB): the MCM is composed of multiple SMBs. Each SMB has three CT inputs and
behaves much like an independent three-phase meter. See 2.2 Multi-Circuit Metering for more
details.

Page 4 of 27 MCM-Inst-1.10
2 Overview
Congratulations on your purchase of the Multi-Circuit Meter for Modbus®(MCM) watt/watt-hour meter.
The MCM can measure 100 to 600 Vac, single-phase and three-phase, wye and delta services. It
supports demand-side management (DSM), submetering, energy monitoring, billing, and renewable
energy applications.
There are two communication versions of the MCM:
●MCM...MB... - Communicates using Modbus RTU over EIARS-485 two-wire twisted-pair links.
●MCM...MBT... - Communicates using Modbus TCP over Ethernet TCP/IP networks.
The MCM meets the revenue metering ANSI C12.1 Class 1 standard when used with class 0.6 current
transformers (CTs) and meets ANSI C12.20 Class 0.5 with class 0.2 or class 0.3 CTs.
The MCM includes the multi-circuit meter, a NEMA rated enclosure, a DC power supply, circuit protec-
tion (fuses or circuit breaker), and terminal blocks, all prewired as a UL 508A Listed industrial control
panel, ready for mounting.
2.1 Model Number Scheme
The MCM is available with many different model numbers. The following section explains how to
decode the MCM model numbers.
MCM<NumCTs>-<VoltageGroup>-<Comm>-<Enclosure><Protection> Opt <Options>
<NumCTs> - The number of CTs (or current sensors), which may be 12, 24, 36, 48, 60, 72, or 84. For
example: MCM12. Each submeter in the MCM has three CT inputs, so the number of submeters will
be the number of CTs divided by three: 4, 8, 12, 16, 20, 24, or 28.
<VoltageGroup> - The measurement circuitry on all MCM models can measure 100 to 600 Vac, but
the power supply configuration depends on the electrical service type. The voltage group (A, B, C,
D, or E) selects the appropriate configuration. See the table below to verify that the voltage group
matches your electrical service type. If possible, choose from the bold entries in the table below as
they are the most common.
Table 1: MCM Voltage Groups
Voltage
Group Power Wiring Description Supported Electrical Service Types
ADirect from the overcurrent pro- tection to the AC/DC power supply
(N, L1)
1-Phase, 2-Wire 120V with neutral
1-Phase, 3-Wire 120/240V
3-Phase, 4-Wire 120V/208Y
1-Phase, 2-Wire 230V with neutral
3-Phase, 4-Wire 230V/400Y
3-Phase, 4-Wire Delta 120/208/240V with neutral
3-Phase, 4-Wire Delta 240/415/480V with neutral
BDirect from the overcurrent protec- tion to the AC/DC power supply (L1,
L2)
1-Phase, 2-Wire 208V (no neutral)
1-Phase, 2-Wire 240V (no neutral)
3-Phase, 3-Wire 208-240V Delta (no neutral)
1-Phase, 3-Wire 120/240V
3-Phase, 4-Wire 120V/208Y
3-Phase, 4-Wire Delta 120/208/240V with neutral
C
From the overcurrent protection
to the step-down transformer (L1,
L2) 480V tap to the AC/DC power
supply
3-Phase, 4-Wire 277V/480Y with neutral
3-Phase, 3-Wire 400V Delta (no neutral)
3-Phase, 3-Wire 480V Delta (no neutral)
3-Phase, 4-Wire 230V/400Y
3-Phase, 4-Wire Delta 240/415/480V with neutral

MCM-Inst-1.10 Page 5 of 27
DFrom the overcurrent protection to the step-down transformer (N, L1)
277V tap to the AC/DC power supply
1-Phase, 2-Wire 277V with neutral
3-Phase, 4-Wire 277V/480Y with neutral
EFrom the fuse to the step-down transformer (L1, L2) 600V tap to the
AC/DC power supply
3-Phase, 4-Wire 347V/600Y with neutral
3-Phase, 3-Wire 600V Delta (no neutral)
<Comm> - The communication type. The MCM does not support both RS-485 and Ethernet in one
model.
●MB - Modbus RTU using RS-485
●MBT - Modbus TCP using Ethernet and TCP/IP
<Enclosure> - The enclosure field specifies one of the following enclosure options:
●ME3 - Steel NEMA 4 enclosure, 12 to 48 CTs, 12 in. × 12 in. × 6 in.
●FE1 - Fiberglass NEMA 4X enclosure, 12 to 48 CTs, 12 in. × 12 in. × 6 in.
●ME4 - Steel NEMA 4 enclosure, 60 to 84 CTs, 16 in. × 14 in. × 6 in.
●FE2 - Fiberglass NEMA 4X enclosure, 60 to 84 CTs, 16 in. × 14 in. × 8 in.
<Protection> - The protection field specifies the overcurrent protection as one of the following:
●C- Three-phase circuit breaker, rated up to 480 Vac; also acts as a disconnect.
●F- Three-phase fuse block, rated for 600 Vac; typically used with voltage group E. The fuse holder
is not rated for use as a disconnect.
●N- No circuit protection. The MCM provides field wiring terminal blocks in place of the circuit
protection. An external disconnect and overcurrent protection are required.
Opt <Options> - Some models may include additional options, such as Opt EP, to configure the
MCM for even parity communications. See the datasheet for all options.
The four most common models follow:
●MCM24-A-MB-FE1C - 24 CTs, 120 - 240 Vac, fiberglass enclosure, circuit breaker
●MCM24-A-MB-ME3C - 24 CTs, 120 - 240 Vac, steel enclosure, circuit breaker
●MCM72-A-MB-FE2C - 72 CTs, 120 - 240 Vac, fiberglass enclosure, circuit breaker
●MCM72-A-MB-ME4C - 72 CTs, 120 - 240 Vac, steel enclosure, circuit breaker
2.2 Multi-Circuit Metering
The CCS MCM is organized into multiple three-element (or three-phase) submeter blocks (SMB).
Each SMB behaves as an independent meter, with a different Modbus address. For example, an
MCM12-A-MB-FE1C supports twelve current transformers and contains four SMBs, each with three
CT inputs. This design has several implications.
●Each submeter block has the same Modbus register list as a regular WattNode®meter.
●The SMBs’ Modbus addresses start with the primary SMB’s address (ADDR+0) and increments
by one for each SMB (ADDR+1, etc.). The address can be configured with the DIP switch or using
the Address Modbus register.
●Communication settings can only be changed on the primary submeter (ADDR+0) and will auto-
matically cascade to all other SMBs in the MCM.
●All SMBs use the same baud rate and parity settings.
●The sum and average registers will only sum or average the metering elements within a single
SMB. Readings from different SMBs can be combined externally.
●Each SMB independently measures the line voltages and line frequency, so the reported values
will differ slightly from one submeter to another.
●The SMB readings will not always update simultaneously.

Page 6 of 27 MCM-Inst-1.10
2.3 Additional Literature
●Continental Control Systems, LLC website: ctlsys.com product and support pages
●MCM product page: https://ctlsys.com/product/mcm/
●MCM support page: https://ctlsys.com/support/mcm/
●Install record: https://ctlsys.com/s/mcm-install-rec/
●Datasheet: https://ctlsys.com/m/MCM-Datasheet.pdf
●Modbus register list: https://ctlsys.com/m/WND-Modbus-Registers-FW37.xls

MCM-Inst-1.10 Page 7 of 27
3 Installation
ADDR+02 ADDR+03 ADDR+01 ADDR+00
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
+
–
5Vdc
V
N
V
A
V
B
V
C
All CT connectors
use the same
numbering
sequence (1, 2, 3)
and white/black
wire orientations.
1 2 3
1
0
O
N
Bias-
Bias+
Termination
Modbus
RTU
RS-485
A-
B+
C
1 2 3 4 5 6 7 8
1 0
O
N
Baud Rate
Address
Modbus
TCP
Ethernet
RJ45
ADDR+06 ADDR+07 ADDR+05 ADDR+04
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
ADDR+14 ADDR+15 ADDR+13 ADDR+12
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
ADDR+10 ADDR+11 ADDR+09 ADDR+08
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
CT1
CT2
CT3
ADDR+26 ADDR+27 ADDR+25 ADDR+24
ADDR+22 ADDR+23 ADDR+21 ADDR+20
ADDR+18 ADDR+19 ADDR+17 ADDR+16
Figure 1: Connection Diagram

Page 8 of 27 MCM-Inst-1.10
The figure above shows all possible connections for an MCM84, including both Modbus RTU and
Modbus TCP, even though both will not be present on a single MCM. The line voltage connections
in the lower-right are factory wired to the circuit protection, and the 5 Vdc connections are factory
wired to the power supply. Models of the MCM with fewer circuits follow similar layouts but with fewer
modules. Each MCM ships with a connection diagram affixed inside the front door.
The connection diagram shows the position (CT1, CT2, CT3) and polarity (white, black) of each
current transformer input.
3.1 Installation Record
The MCM is provided with an installation record to plan and document the installation. The first page
documents general information: model number, serial number, electrical service, Modbus settings,
RS-485 settings, Ethernet settings, etc. The additional pages of meter and CT schedule document
each load and current transformer input to the MCM. It is essential to document the loads and CT
configurations because the meter must be correctly programmed to match the actual installa-
tion. To download additional copies, see https://ctlsys.com/support/mcm-installation-record/.
The meter and CT schedule contains several columns of information. The electrician or installer
should fill in most of these columns, but the integrator will typically fill in the MeterConfig. See below
for an example schedule.
Channels: The MCM is composed of one or more modules (PCBs), each with 12 CT inputs (chan-
nels). The channels column shows one block for each set of 12 channels. The numbering, 1-12,
13-24, etc., is just informational and will not be used when accessing data from the MCM.
Submeter Block: As described above, the MCM is composed of four or more SMBs, each behaving
like a WattNode meter with three CT inputs. Each SMB has its own Modbus address, based on
the address (ADDR) set with the DIP switch on the primary SMB. For example, if you set the DIP
switch address to 2, then ADDR+0 = 2, so the address of the primary SMB will be 2.
Modbus Addr: The Modbus address field is filled in by hand, by adding the DIP switch address to the
offset documented in the SMB column. For example, if the DIP switch address is 2 and the subme-
ter block shows ADDR+3, then fill in the Modbus address as 5.
CT#: Each SMB has three CT inputs. This column shows the CT numbers printed on MCM boards
and on the wiring diagram.
Panel: You may use the panel column to identify the panelboard or circuit breaker panel. Be sure to
use this column if you are metering more than one panel with a single MCM.
Ckt#: Use this column to record the circuit number within the panelboard. These are the numbers
printed adjacent to circuit breakers and on the panel schedule.
CT Amps: It is important to record the rated amperage of each current transformer. In many cases,
the CT amps will match the circuit breaker rating, but this is not always true.
L1, L2, or L3: Use this column to record the line voltage phase associated with this current trans-
former. You may refer to the phases as L1, L2, L3 or as ØA, ØB, ØC.
MeterConfig: The integrator will normally configure the MeterConfig registers and fill in this column.
The MeterConfig value depends on whether a CT input is associated with L1, L2, or L3, and
whether the CT measures a line-to-neutral or a line-to-line load.
Load Name/Description: Fill in this column to document the load for each MCM input.

MCM-Inst-1.10 Page 9 of 27
3.1.1 Example Meter and CT Schedule
Chan-
nels Submeter Block Modbus Addr CT #Panel Ckt #CT Amps L1, L2, or L3 Meter Config Load Name / Description
1-12
ADDR+0 2
CT1 P3 1 20 L1 10 Foyer Lighting
CT2 P3 3 20 L2 20 Foyer Outlets #1
CT3 P3 5 20 L3 30 Foyer Outlets #2
ADDR+1 3
CT1 P3 7 20 L1 10 Kitchen Outlets #1
CT2 P3 9 20 L2 20 Kitchen Outlets #2
CT3 P3 11 20 L3 30 Kitchen Outlets #3
ADDR+2 4
CT1 P3 2 50 L1 10 RTU #1
CT2 P3 4 50 L2 20 |
CT3 P3 6 50 L3 30 |
ADDR+3 5
CT1 P3 8 50 L1 90 Compressor (208V, no neutral)
CT2 P3 10 50 L2 50 |
CT3 P3 13 20 L1 10 Kitchen Outlets #4
ADDR+4 6
CT1 P3 15 20 L2 20 Men’s Bathroom Lighting
17 20 L2 20 Women’s Bathroom Lighting
CT2 P3
Figure 2: Sample Installation Record
In this example, the panel (P3) is a 120/208V three-phase wye panel. All of the loads have a neutral
connection except the delta connected compressor.
The first six circuits are single-phase, 20A, lighting and outlet branch circuits. For all six, L1 is matched
with CT1, L2 is matched with CT2, and L3 is matched with CT3. This is the simplest configuration and
does not require any changes to the MeterConfig registers.
The next three CT inputs are monitoring a three-phase, 50A, rooftop unit (RTU) load. Again the line
voltages are matched with the CT inputs and do not require any changes to MeterConfig.
CT1 and CT2 of Modbus address 5 are monitoring two legs of a delta connected compressor. The
MCM only requires two CTs for delta loads, but if only two CTs are used, then the MeterConfig
registers must be changed. In this case, the CT1 input is associated with the L1-L3 (VoltAC) line
voltage (MeterConfig = 90), while the CT2 input is associated with the L1-L2 (VoltAB) line voltage
(MeterConfig = 50). Delta loads can also be measured with three current transformers using the
default MeterConfig settings.
CT3 of Modbus address 5 is monitoring a single-phase outlet load (Kitchen Outlets #4). CT3 monitors
the load on L1 or ØA (phase A), so MeterConfig must be changed to 10.
The final two loads in the example are lighting loads, both on L2 (ØB), so both need to have
MeterConfig set to 20.
3.2 Electrical Service or Load Types
The MCM supports any electrical service from 100 to 600 Vac, line-to-neutral or line-to-line, 50 to
60 Hz, single-phase, split-phase, or three-phase, wye or delta, two-wire, three-wire, or four-wire. It

Page 10 of 27 MCM-Inst-1.10
monitors multiple branch circuits or loads on a single service. Note: when describing service types, the
number of wires only includes neutral and line conductors, not the ground conductor.
The MCM only has one set of line voltage connections, so all submeter blocks (SMBs) share the same
line voltages. However, one MCM can monitor different types of loads powered by the same service.
For example, if your MCM line voltage connection is 120/208 wye, the MCM could simultaneously
monitor three-phase wye loads, three-phase delta loads (no neutral), two-wire line-to-line loads (e.g.,
L1 to L2), and single-phase line-to-neutral loads.
Internally, each SMB acts as three separate single-phase meters, one tied to each CT input. By
default, the meter associates CT1 with VoltA(or VA- VN), CT2 with VoltB, and CT3 with VoltC. This
default configuration may be changed using the MeterConfig registers. When this guide refers to the
MeterConfig registers, there are three registers, MeterConfig1, MeterConfig2, and MeterConfig3,
associated with CT1, CT2, and CT3 respectively.
Connect the line voltages to the MCM inputs, as shown in the following sections. If you are monitoring
different types of loads, be sure to use the line voltage connection for the type of load with the most
wires connected.
3.2.1 Three-Phase, Four-Wire Wye
This is a common commercial and industrial service that includes a neutral conductor. Load #1
is three-phase and could be wye or delta connected. Loads #2, #3, and #4 are single-phase,
line-to-neutral.
V
B
V
C
V
N
V
A
CT2
ADDR+1ADDR+0
CT1CT3CT2 CT1CT3
Additional Loads
Earth
L3 L2 L1 N
Meter Power
Load #1,
3Ø
Load #2, 1Ø
Load #3, 1Ø
Load #4,1Ø
Figure 3: Three-Phase Four-Wire Wye
This service supports the following types of loads:
●Three-phase, four-wire, wye (with neutral): This requires three CTs. You do not need to change
the MeterConfig registers if you wire the CTs as shown for load #1 above, with CT1 placed
around L1, CT2 around L2, and CT3 around L3.
●Three-phase, three-wire, delta (no neutral): See 3.2.2 Three-Phase, Three-Wire Delta below
for details.
●Single-phase, line-to-neutral: This is metered with a single CT, as illustrated for loads #2, #3,
and #4. The MeterConfig registers may need to be changed.

MCM-Inst-1.10 Page 11 of 27
○MeterConfig = 10 for the CT around L1
○MeterConfig = 20 for the CT around L2
○MeterConfig = 30 for the CT around L3
●Single-phase, two-wire, line-to-line, without neutral: See 3.2.2 Three-Phase, Three-Wire
Delta below for details.
●Single-phase, three-wire, line-to-line, with neutral: See 3.2.3 Single-Phase, Three-Wire
(Split-Phase) below for details.
For loads with more than one CT, we recommend keeping all CTs on the same SMB.
3.2.2 Three-Phase, Three-Wire Delta
This service is common in commercial and industrial settings. It does not include a neutral conductor.
Load #1 is three-phase, three-wire, delta, measured with three CTs. Load #2 is three-phase, three-
wire, delta, measured with two CTs. Load #3 is single-phase, line-to-line, and measured with one CT.
V
B
V
C
V
N
V
A
CT2
ADDR+1ADDR+0
CT1CT3CT2 CT1CT3
Additional Loads
L3 L2 L1
Meter Power
Load #1,
3Ø
Load #2,
3Ø, 2 CTs
Load #3,
1Ø, 1 CT
Earth
Figure 4: Three-Phase Three-Wire Delta
This service supports the following types of loads:
●Three-phase, three-wire, delta (no neutral): You may meter this with either three or two CTs.
○With three CTs wired as shown for load #1 above, use the default MeterConfig values:
■MeterConfig1 = 10
■MeterConfig2 = 20
■MeterConfig3 = 30
○With two CTs wired as shown for load #2 above, use the following MeterConfig values:
■MeterConfig1 = 90
■MeterConfig2 = 50
●Single-phase, line-to-line: You may meter this with one or two CTs.
○With two CTs, use:
■MeterConfig = 10 for any CT around L1

Page 12 of 27 MCM-Inst-1.10
■MeterConfig = 20 for any CT around L2
■MeterConfig = 30 for any CT around L3
○With one CT, assign MeterConfig as follows:
■The load connected from L1 (ØA) to L2 (ØB) and the CT around L1: MeterConfig = 40
■The load connected from L1 (ØA) to L2 (ØB) and the CT around L2: MeterConfig = 70
■The load connected from L2 (ØB) to L3 (ØC) and the CT around L2: MeterConfig = 50
■The load connected from L2 (ØB) to L3 (ØC) and the CT around L3: MeterConfig = 80
■The load connected from L3 (ØC) to L1 (ØA) and the CT around L3: MeterConfig = 60
■The load connected from L3 (ØC) to L1 (ØA) and the CT around L1: MeterConfig = 90
For loads with more than one CT, we recommend keeping all CTs on the same submeter block.
3.2.3 Single-Phase, Three-Wire (Split-Phase)
This is the typical North American residential service at 120/240 Vac with a neutral connection. Load
#1 is three-wire, with neutral, measured with two CTs. Load #2 is two-wire, with neutral, measured
with one CT. Load #3 is two-wire, line to line, without neutral, measured with one CT.
V
B
V
C
V
N
V
A
CT2
ADDR+1ADDR+0
CT1CT3CT2 CT1CT3
Load #1
Load #2
Load #3
Additional Loads
Earth
L2 L1 N
Meter Power
Figure 5: Single-Phase, Three-Wire
This service supports the following types of loads:
●Single-phase, line-to-neutral: This is metered with a single CT, as illustrated for load #2. The
MeterConfig registers may need to be changed.
○MeterConfig = 10 if the CT is around L1
○MeterConfig = 20 if the CT is around L2
●Single-phase, two-wire, line-to-line, without neutral: See 3.2.2 Three-Phase, Three-Wire
Delta above for details.
●Single-phase, three-wire, line-to-line, with neutral: This is metered with two CTs, as illustrated
for load #1. The MeterConfig registers may need to be changed.
○MeterConfig = 10 for the CT around L1
○MeterConfig = 20 for the CT around L2
For loads with more than one CT, we recommend keeping all CTs on the same submeter block.

MCM-Inst-1.10 Page 13 of 27
3.2.4 Grounded Leg Service
In rare cases with delta services or single-phase two-wire, line-to-line services, one of the phases may
be grounded. The MCM will correctly measure the voltages, power, and energy for grounded leg ser-
vices. Depending on how the MeterConfig registers are programmed, the measured voltage, power,
and energy for the grounded phase may be zero, and the status LEDs will not light for the grounded
phase. This type of service may result in unusual power factors.
See the web article Corner-Grounded Delta Circuits for more information.
3.2.5 Four-Wire Delta Service
There are several names for this service type, including high-leg, wild-leg, stinger leg, or wild phase. It
is a three-phase delta service with a center-tap on one of the transformer windings to create a neutral
for single-phase loads. These occur in NorthAmerica in two configurations: 120/208/240 Vac and
240/415/480 Vac.
With the MCM, this service type can be measured just like any three-phase, four-wire wye service. By
convention, you should connect the VBterminal to the high leg. See the web article Four-Wire Delta
Circuits for more information.
3.3 Installation Checklist
See the sections referenced below for installation details.
□Turn off power before making line voltage connections.
□Mount the MCM (see 3.4).
□If needed, connect any external circuit protection and disconnects (see 3.5.1).
□Connect the line voltage wires (see 3.5).
□Mount the CTs around the line conductors. Make sure the CTs face the source (see 3.6).
□Connect the twisted white and black wires from the CTs to the black terminal blocks on the
MCM, matching the wire colors to the white and black dots on the MCM label (see 3.6.2).
□Document the information for each circuit (load) using the installation record. Whoever does
the commissioning with need this record (see 3.1).
□Connect the RS-485 output (for Modbus RTU) or the RJ45 Ethernet jack (for Modbus TCP) of
the MCM to the monitoring equipment (see 3.7).
□Configure the DIP switches (see 3.7.3).
□Check that all the wires are secure in the terminal blocks by tugging on each wire.
□Turn on power to the MCM.
□Configure the appropriate MCM registers (see 4.1).
□Verify correct operation using the LEDs or the Modbus interface (see 4.2, 4.4).
3.4 Mounting
The MCM is available in four NEMA rated enclosures, small and large, steel and fiberglass.
●Protect the MCM from temperatures outside its limits. See 5.6 Environmental.
●The MCM enclosure is rated for NEMA 4 (steel) or NEMA 4X (fiberglass). If you need to preserve
this rating, be sure to use fittings with the same ratings.
The MCM enclosure can weigh up to 30 pounds (14 kg), not including the weight of any connected
conduit. Mount it securely using the four holes in the mounting tabs. The steel enclosures include fixed
mounting tabs with four 5/16 inch (7.9 mm) holes, while the fiberglass enclosures use detachable
mounting tabs with four 11/32 inch (8.7 mm) holes.

Page 14 of 27 MCM-Inst-1.10
3.5 Line Voltage Connections
N
LINE VOLTAGE
CONNECTIONS
VIOLET
GREEN WHITE
BLACK
SLATE
GROUND
TERMINALS
GB1
TB4
L1 L2 L3
CB1
Figure 6: Circuit Breaker
N
LINE VOLTAGE
CONNECTIONS
VIOLET
GREEN WHITE
BLACK
SLATE
GROUND
TERMINALS
GB1
TB4
L1 L2 L3
TB1 TB2 TB3
Figure 7: No Protection
N
LINE VOLTAGE
CONNECTIONS
VIOLET
GREEN WHITE
BLACK
SLATE
GROUND
TERMINALS
GB1
TB4
L1 L2 L3
FH1
FU1
FU2 FU3
Figure 8: Fuse Block
3.5.1 Circuit Protection
The MCM is considered “permanently connected equipment” and requires a disconnecting means
(circuit breaker or disconnect switch) and overcurrent protection (fuse or circuit breaker). Most models
include a three-phase circuit breaker that functions as both a disconnect and overcurrent protection.
The MCM draws less than 0.2 amps.
Note that the circuit breaker is only rated for operation from -25°C to +55°C (-13°F to 131°F).
●If you purchase a model with a three-phase fuse block, you will need to provide an external
disconnect.
●Models with no protection will need an external disconnect and overcurrent protection.
○Any external disconnect or circuit breaker must be clearly marked, suitably located, and easily
reached.
○Use circuit breakers or fuses rated for 20 amps or less and rated for the service voltage.
○Use ganged circuit breakers when monitoring more than one line voltage.
○The circuit breakers or fuses must protect all hot line voltages: L1, L2, and L3. Neutral does
not need overcurrent protection.
○The circuit protection/disconnect system must meet IEC 60947-1 and IEC 60947-3, as well as
all national and local electrical codes.
3.5.2 Line Wiring
● Always turn off the power before connecting the line voltages.
● For the line voltage wires, CCS recommends 18 to 12 AWG stranded wire, type THHN, MTW, or
THWN, 600 V.

MCM-Inst-1.10 Page 15 of 27
● Use copper conductors only. The screw terminals are only rated for copper wire.
● Do not place more than one wire in a screw terminal; use wire nuts or terminal blocks if needed.
● Verify that the highest line-to-neutral or line-to-line voltage is nominally between 100 and 600 Vac.
The absolute maximum operating voltage is 690 Vac.
●Torque all screws as specified on the information label on the inside of the enclosure door.
Connect neutral (if present) to the white DIN rail screw terminal (TB1) labeled N.
Connect line voltage conductor to L1, L2, and L3 labeled terminals on the circuit breaker, fuse block,
or DIN rail screw terminals.
Connect each line voltage wire, as shown in Figure 6 through Figure 8 above.
3.5.3 Grounding
The MCM includes a grounding block (GB1) in the upper-right corner of the backplate. Connect earth
ground to any available position. See Figure 6 through Figure 8 above.
If you are using a fiberglass enclosure, use grounded conduit bushings and wire the bushings to the
grounding block.
3.6 Current Transformer Connections
The meter must be used with UL Listed or UL Recognized current sensors or transformers. UL has
only approved listed CTs for retrofit applications in panelboards; do not use recognized CTs for this
application.
The standard MCM supports CTs with a 0.33333 Vac output (one-third volt). With the correct options,
the MCM can support CTs with a 40 milliamp output: contact CCS for details.
3.6.1 Current Transformer Installation
See the web article Selecting Current Transformers for information on selecting appropriate current
transformers (CTs).
●WARNING: To reduce the risk of electric shock, always open or disconnect the circuit from the
power-distribution system or the building service before installing or servicing CTs.
●WARNING: When using UL Recognized CTs, they must be installed on insulated conductors only
and maintained away from all live parts.
●Do not use 1 amp or 5 amp current output CTs!
●Treat CTs as class 1 circuits. They are not suitable for Class 2 wiring methods.
●Use plastic cable ties to secure the current transformers and route the lead wires so that they do
not directly contact uninsulated live terminals or conductors.
●Split-core CTs can be opened for installation around a conductor. A nylon cable tie may be
secured around the perimeter of the CT to prevent inadvertent opening.
●Do not install current transformers where they would: 1) exceed 75 percent of the wiring space of
any cross-sectional area within the equipment, 2) would block ventilation openings, or 3) would be
in an area of breaker arc venting.
●See the CT datasheets for the maximum input current ratings.
●To minimize current measurement noise, avoid extending the CT wires beyond 100 feet (30
meters), especially in noisy environments. You may extend the wires with twisted-pair wire 18 to
14 AWG, rated for 300 V or 600 V (not less than the service voltage) and shielded if possible.
Find the source arrow or label “THIS SIDE TOWARD SOURCE” on the CT and face/point toward
the source of current. CTs are directional, so if they are mounted backward or with their white and
black wires swapped, the measured power will be negative. The power status LEDs indicate nega-
tive measured power by flashing red. Note: negative power and red LEDs may also occur if the

Page 16 of 27 MCM-Inst-1.10
MeterConfig registers have not been configured yet. This can be corrected after installation using
the CtDirections register.
Install the CTs around the phase conductors to be measured as shown in section 3.2 Electrical
Service or Load Types above. Connect the CT leads to the MCM.
For revenue accuracy, use revenue-grade current transformers; other CTs are less accurate and may
not provide revenue accuracy. Contact sales for more information on appropriate CTs.
3.6.2 CT Wiring
The current transformers connect to the six-position black screw terminal blocks for each submeter
block. Connect the white and black CT wires to the terminals marked CT1, CT2, and CT3. See Figure
1for an overview. Excess length may be trimmed from the wires if desired.
The white and black lead wires mark the CT polarity. The polarity for the MCM is marked with WHT
and BLK on the MCM board and with white and black circles on the connection diagram label on the
inside of the front cover.
Connect each CT with the white wire aligned with the white dot on the connection diagram, and the
black wire aligned with the black dot. Be sure to fill in the meter and CT schedule for each CT; see
section 3.1 Installation Record above. You will need this information for correct power measurement!
Torque the screws to 3.5 lbf·in (0.4 N·m).
3.7 Modbus RTU (RS-485) Communication
This section only applies for MCM-MB models (MCMxx-y-MB-zzzz) with Modbus RTU communica-
tion using the RS-485 physical link. The MCM-MB can be connected to PCs with RS-485 interfaces,
gateways, data loggers, and other devices that accept RS-485 Modbus RTU.
3.7.1 RS-485 Cables
There are many choices for RS-485 cabling. Ideally, use cable specifically rated for RS-485 applica-
tions as it will have the best impedance for long distances to minimize interference and reflections.
However, for distances up to 100 meters, especially at baud rates of 38,400 or lower, a special
RS-485 cable is normally not required. See RS-485 Cables for Modbus for more information.
There are some standard conductor configurations for RS-485 cables:
●Two conductors without shield: we do not recommend using this type
of cable because the MCM design expects the common terminal to be
connected.
●Two conductors with a shield: use the two conductors for the A- and
B+ terminals, use the shield for C(common). If you connect the shield
to earth, only connect it at the Modbus master device.
●Three conductors without a shield: use the three conductors for the
A-, B+, and C(common). If two of the conductors are twisted together
as a pair, use those for the A- and B+ terminals.
●Three conductors with a shield: use the three conductors for the A-,
B+, and C(common). If two of the conductors are twisted together as
a pair , use those for the A- and B+ terminals. The shield may be
connected to earth at the Modbus master device for improved noise
immunity.
●If there are additional conductors, they may be left disconnected.
●Use a twisted-pair cable to prevent interference.
●For longer distances (>30 meters) or electrically noisy environments,
use shielded cable.
A
-
B+
C
RS-485
MCM #1
RS-485
A- B+ C
MCM #2
RS-485
A- B+ C
Figure 9: RS-485 Wiring

MCM-Inst-1.10 Page 17 of 27
3.7.2 RS-485 Connection
RS-485 wiring can be complex when multiple devices are connected, when running wires for long
distances, and when using termination and biasing resistors.
●The MCM RS-485 outputs are electrically isolated from dangerous voltages.
●If the output wiring runs near line voltage wiring, use wires or cables with a 300 V or 600 V rating
(not less than the service voltage).
●If the output wiring runs near bare conductors, it must be double insulated or jacketed.
●RS-485 wiring may be daisy-chained between devices. Avoid a star or home run wiring system,
where each device is wired back to the Modbus master, as this can cause signal reflections.
●You may install two wires into each screw terminal by twisting the wires together first.
●Torque the screws to 3.5 lbf·in (0.4 N·m).
●Note: one loose wire can disable an entire network section.
3.7.3 Modbus RTU DIP Switches
The MCM-MB uses two DIP switches to configure the address, the baud rate, termination, and
biasing.
1 2 3 4 5 6 7 8
1 0
O
N
1 2 3
1
0
O
N
Baud Rate
Address
Bias-
Bias+
Termination
Figure 10: DIP Switches
Use DIP switches 1-6 from the upper switch to select the base Modbus address (1 to 63). Each
submeter block has its own offset from the base address. The first submeter’s address is the base
address, the next is the base plus one (designated as “ADDR+1”), and so on. Note: do not set DIP
switches 1-6 all off, since this would result in a base address of 0, which is invalid.
Table 2: Modbus Address DIP Switch
DIP Switch 1 2 3 4 5 6
On (1) Value 1 2 4 8 16 32
Address Examples
11, On 0, Off 0, Off 0, Off 0, Off 0, Off
1+2+4 = 7 1, On 1, On 1, On 0, Off 0, Off 0, Off
4+16 = 20 0, Off 0, Off 1, On 0, Off 1, On 0, Off
1+2+16+32
= 51 1, On 1, On 0, Off 0, Off 1, On 1, On
For example, if the DIP switch address is set to 2, thenADDR+0 = 2, so the address of the primary
SMB will be 2, the address of the next SMB will 3, and so on.

Page 18 of 27 MCM-Inst-1.10
Select the baud rate with DIP switch positions 7 and 8 (see below). The change will take effect imme-
diately. Other baud rates may be factory configured or programmed using the BaudRate register.
Table 3: Modbus Baud Rate DIP Switch
Baud Rate DIP Switch 7 DIP Switch 8
9,600 (default) 0, Off 0, Off
19,200 0, Off 1, On
38,400 1, On 0, Off
115,200 1, On 1, On
The RS-485 settings default to no parity, 8 data bits, and one stop bit (N81). Other parity and stop bit
settings may be configured with factory options or with the Modbus ParityMode register.
Select the RS-485 termination and biasing using the lower DIP switches. Set DIP switch 1 to the ON
position to enable 120 Ωtermination. Set DIP switches 2 and 3 to the ON position enables RS-485
biasing with 1.2 kΩohm resistors.
3.8 Modbus TCP (Ethernet) Communication
This section only applies to MCM-MBT models (MCMxx-y-MBT-zzzz) with Modbus TCP using the
Ethernet physical link. These models may have DIP switches present, but if so, they will be inactive.
The MCM-MBT uses a Lantronix XPort-IAP-05 with Modbus (part number XP1001000M-05R) to
provide the Modbus TCP Ethernet interface. The XPort includes the following features:
●Modbus bridge from Modbus TCP (port 502) to Modbus RTU
●DHCP for automatic IP address assignment
●Telnet interface (port 9999) for advanced configuration
●Automatic discovery of devices (port 30718) with DeviceInstaller
●Supports ARP, ICMP (ping), and TFTP
Some XPort models support other features, such as a web interface, but this model does not.
The directions in this guide should be sufficient for most installations, but for more advanced configu-
ration or additional details, see the following Lantronix links.
●Main XPort product page: https://www.lantronix.com/products/xport/
●DeviceInstaller utility: https://ltrxdev.atlassian.net/wiki/spaces/LTRXTS/pages/106070471
●DeviceInstaller user’s guide: http://www.lantronix.com/wp-content/uploads/pdf/
DeviceInstaller_UG.pdf
●XPort user’s guide: https://cdn.lantronix.com/wp-content/uploads/pdf/XPort_UG.pdf
●XPort datasheet: https://cdn.lantronix.com/wp-content/uploads/pdf/XPort_DS.pdf
●Modbus protocol guide: https://cdn.lantronix.com/wp-content/uploads/pdf/Modbus_Proto-
col_UG_Rev_J.pdf
3.8.1 Ethernet Cables
The MCM-MBT communicates at 10 Mbit or 100 Mbit and will work with CAT5, CAT5e, CAT6, or better
Ethernet cables with RJ45 plugs. Generally, the Ethernet cable will connect to an Ethernet switch,
which then connects to the local area network (LAN). It may also be connected directly to another
device, although a crossover cable may be required.
●The MCM-MBT Ethernet output is electrically isolated from dangerous voltages.
●If possible, route and secure the Ethernet cable away from line voltages.
●If you run the Ethernet cable near line voltage wiring, use cables with a 300 V or 600 V rating (not
less than the service voltage).
●If the output cable runs near bare conductors, it must be double insulated or jacketed.

MCM-Inst-1.10 Page 19 of 27
3.8.2 RJ45 Jack LED Indications
There are two LEDs on the RJ45 jack. They are used to indicate the connection speed and activity. In
addition to these, the COMM LED shows Modbus traffic (see 4.3 Modbus Communication LED).
Left LED (Link)
●Off = No link
●Amber = 10 Mbit
●Green = 100 Mbit
Right LED (Activity)
●Off = No link
●Amber = half-duplex
●Green = full-duplex
3.8.3 IP Address Configuration - DHCP
There are two methods of assigning the IP address to the MCM-MBT: DHCP and static IP. This section
describes the DHCP options, while 3.8.5 Advanced Configuration describes assigning a static IP.
We recommend using the MCM-MBT default DHCP configuration combined with a DHCP reserva-
tion on your DHCP server. A DHCP reservation tells the DHCP server to always assign the same IP
address to a particular device, based on its MAC address. With this approach, the MCM-MBT will
always have a known IP address. For this approach, you need the MAC address of the MCM-MBT,
which is printed on the top label of the XPort like 00-80-A3-D4-50-CA (note, all XPort MAC addresses
start with 00-80-83). The same MAC address (without the hyphens) is encoded in the Code 128
barcode on the label.
Figure 11: Lantronix XPort MAC Address Label
Once you know the MAC address, you can program that into your DHCP server. For larger organiza-
tions, contact your IT department for this step. For more information, search the internet for “DHCP
reservation”. A similar approach is to let your DHCP server assign an IP address to the MCM-MBT,
then find the assignment and convert it to a DHCP reservation so that it does not change in the future.
Note: If you do not use a DHCP reservation or a static IP address, the DHCP server may not
continue to reassign the same address over time.
If you are not using DHCP, see 3.8.5 Advanced Configuration below for information on assigning a
static IP address.
3.8.4 Lantronix DeviceInstaller Utility
The Lantronix DeviceInstaller utility for Windows finds all Lantronix devices on a LAN (local area
network), allows some basic query features, and includes a telnet client for advanced configuration.
It is not necessary to use DeviceInstaller, but may be helpful if your MCM-MBT was automatically
assigned an IP address, and you cannot determine the address, or if you need to perform advanced
configuration.

Page 20 of 27 MCM-Inst-1.10
Search the internet for Lantronix DeviceInstaller to find the latest version. Download and install the
program, then run it. Windows may prompt you for firewall settings: be sure to allow it access to your
local network. It uses port 30718 (0x77FE) to discover Lantronix devices and port 9999 for telnet
access. On start up, it will search for all known Lantronix devices. If it finds more than one XPort
device, you may need to use the MAC address to determine which is the correct MCM-MBT.
Once you have found the correct meter, you can double-click it to access more details. It may com-
plain it could not access configuration details; this is common and does not indicate a problem. You
may be able to click the Configuration Records tab to read the configuration. See 3.8.5 Advanced
Configuration below for more information.
3.8.5 Advanced Configuration
The XPort supports telnet access for advanced configuration. There are multiple telnet client options:
there is telnet built into the Lantronix DeviceInstaller utility, Windows includes telnet although it may
need to be enabled (see 3.8.6 Windows Telnet Client), and you may use any other telnet client.
The XPort includes a unique default password for telnet access. The factory default password will be
the UL Listing serial number from the label installed in the enclosure. For Figure 12 below, the pass-
word would be “B 84728808” with a space between the B and the number.
Figure 12: UL Listed Label
If you are using the DeviceInstaller, click on the Telnet Configuration tab, then click Connect to con-
nect. If you are using a different telnet client, connect using port 9999. The example below assumes
the MCM’s IP address is 192.168.1.100.
C:\> telnet 192.168.1.100 9999
If you do not know the IP address of the MCM, you will need to determine it by checking your DHCP
server or using the Lantronix DeviceInstaller.
As soon as you are connected, the XPort will prompt you to enter the password. You must type it
correctly on the first try (backspace does not work). As soon as you type the last character, it will show
“Press Enter for Setup Mode”; press Enter to continue. If you make a mistake typing the pass-
word, you will need to disconnect and reconnect to try again.
Now, the XPort telnet interface will display the current configuration. See the figure below for an
example.