Weidmüller EM122-RTU-2P User manual

EM122-RTU-2P
Manual

Revision History
Version
Date
Change
0
2021.3.9
First edition

Contents
General................................................................................................................................................................................................... 5
Copyright..................................................................................................................................................................................... 5
Trademarks.................................................................................................................................................................................. 5
Disclaimer .................................................................................................................................................................................... 5
Meaning of the symbols......................................................................................................................................................... 5
Application notes ...................................................................................................................................................................... 6
About these operating instructions .................................................................................................................................... 7
Incoming goods inspection ............................................................................................................................................................ 8
Scope of delivery....................................................................................................................................................................... 8
Product description ........................................................................................................................................................................... 9
Intended use............................................................................................................................................................................... 9
Specifications............................................................................................................................................................................10
Operating concept..................................................................................................................................................................12
EM configuration tools..........................................................................................................................................................13
Connection options................................................................................................................................................................13
Assembly.............................................................................................................................................................................................14
Installation location ................................................................................................................................................................14
Power supply ............................................................................................................................................................................14
Voltage and current measurement inputs .....................................................................................................................15
Direction of the current.........................................................................................................................................................16
RS485 interface........................................................................................................................................................................16
Terminating resistors ....................................................................................................................................................17
Shielding ...........................................................................................................................................................................17
Cable type ........................................................................................................................................................................18
Maximum cable length ................................................................................................................................................18
Bus structure....................................................................................................................................................................18
Pulse Output.............................................................................................................................................................................20
Examples of electrical connections ...................................................................................................................................21
Configuration and display.............................................................................................................................................................22
Self-check after power on....................................................................................................................................................22
Button functions......................................................................................................................................................................23
Overview of measured value displays..............................................................................................................................24
Voltage and Current .....................................................................................................................................................24
Frequency and Power Factor and Demand ..........................................................................................................25
Power.................................................................................................................................................................................26
Energy Measurement ...................................................................................................................................................27
Configuration menu...............................................................................................................................................................28
Set-up Mode............................................................................................................................................................................28
Set-up Entry Methods...........................................................................................................................................................29
Menu Option Selection................................................................................................................................................29

Number Entry Procedure ............................................................................................................................................29
Change Password ..........................................................................................................................................................30
DIT Demand Integration Time............................................................................................................................................31
Backlit Set-up...........................................................................................................................................................................32
Supply System..........................................................................................................................................................................33
Pulse Output.............................................................................................................................................................................34
Pulse Rate ..................................................................................................................................................................................35
Pulse Duration..........................................................................................................................................................................36
Communication .......................................................................................................................................................................37
RS485 Address................................................................................................................................................................37
Baud Rate .........................................................................................................................................................................38
Parity ..................................................................................................................................................................................39
Stop Bits............................................................................................................................................................................40
CLR......................................................................................................................................................................................41
Modbus Communication Protocol.............................................................................................................................................42
Input Registers, Function code 04.....................................................................................................................................42
Holding Register, Function code 03/10...........................................................................................................................45
Dimensional drawings ....................................................................................................................................................................48
Connecting example .......................................................................................................................................................................48

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General
This manual applies to the products:
7760051003 Energy Meter EM122-RTU-2P
Copyright
This manual is subject to the laws of copyright protection and may not be mechanically or electronically
photocopied, reprinted, reproduced or otherwise reproduced or published in part or as a whole, without the
legally binding, written consent of
Weidmüller Interface GmbH & Co. KG
Klingenbergstraße 26
32758 Detmold Germany
Trademarks
All trademarks and the rights resulting from them remain the property of the trademark holder of these
rights.
Disclaimer
Weidmüller assumes no responsibility for errors or omissions in this manual and assumes no obligation to
keep the contents of this manual up to date.
Meaning of the symbols
The following pictograms are used in this manual:
Dangerous voltage!
Risk of death or serious injury. Disconnect the power before working on the system
and device.
Attention!
Please refer to the documentation. This symbol will warn you of possible dangers that
could occur during assembly, commissioning and operation.
Note!

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Application notes
Please read these operating instructions and all other publications that must be consulted in order to work
with this product (particularly for installation, operation or maintenance).
Please observe all safety regulations and warnings. Non-compliance with the instructions can lead to
personal injury and/or damage to the product.
Any unauthorized alteration or use of this device which exceeds the specified mechanical, electrical or other
operational limits can cause personal injury and/or damage to the product.
Any such unauthorized alterations are grounds for “abuse” and/ or “negligence” in terms of the product‘s
guarantee and thus excludes the warranty for covering any possible resulting damages.
This device must only be operated and maintained by qualified personnel.
Qualified personnel are persons who, due to their respective training and experience, are able to recognize
risks and avoid potential hazards that can be caused by operation or maintenance of the device.
When using the device, the legal and safety regulations required for the respective application must also
be observed.

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Safety is no longer guaranteed and the
device may be dangerous if the device
is not operated according to the
operating instructions.
Only screw terminals with the same
number of poles and the same type may
be plugged together.
All signals connected with the
device’s SELV circuit must also
conform with the SELV provisions.
Conductors consisting of single wires
must be provided with ferrules.
About these operating instructions
These operating instructions are part of the product.
•Read the operating instructions prior to using the device.
•Keep the operating instructions at hand throughout the entire service life of the product and keep ready
for referencing.
•Hand over the operating instructions to each subsequent owner or user of the product.

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Incoming goods inspection
The proper and safe operation of this device requires appropriate transport, proper storage, installation
and assembly as well as careful operation and maintenance. When it is assumed that safe operation is no
longer possible, the device must immediately be taken out of operation and secured against accidental
start-up. Unpacking and packing must be carried out with the usual care, without the use of force and only
with the use of suitable tools. The devices must be visually inspected for proper mechanical condition. It
can be assumed that safe operation is no longer possible if the device, e.g.
•shows visible damage;
•does not work despite intact power supply;
•and was exposed to unfavorable conditions (e.g. storage out- side of the permissible climatic limits
without adaptation to the ambient climate, condensation, etc.) or transport stresses (e.g. falling from a
great height even without exterior visible damage, etc.) for prolonged periods;
•Please check that the is complete before you begin with installation of the device.
Scope of delivery
Quantity
Designation
1
Energy Meter 122
1
Quick guide

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Product description
Intended use
The Energy Meter 122 measures and displays the characteristics of 1P2W, 3P3W, 3P4W’s applications. The
unit provides voltage, current, power, frequency, power-factor, and energy etc.
The Energy Meter 122 is permanently installed in control cabinets or small distribution boards. It can be
installed in any position.
Measurement voltages and measurement currents must originate from the same grid.
Energy Meter EM122-RTU-2P supports max. 100A direct connection, saves the cost and avoid the trouble to
connect external CTs, giving the unit a cost-effective and easy operation.
The measurement results can be displayed and can be read and processed over the RS485 interface.
The Energy Meter 122 designed for mounting in low voltage distributions, containing overvoltage in
measurement category III.
EM122 series have one RS485 remote communication port.

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Specifications
Electrical characteristics
Type of measurement
RMS including harmonics on three phase AC
system (3P, 3P+N)
Measurement
accuracy
Voltage
0.5%
Current
0.5%
Frequency
0.2%
Power Factor
±0.01
Active Power
1%
Reactive Power
2%
Apparent Power
2%
Active Energy
IEC62053-21 Class 1
Reactive Energy
2%
Input-Voltage
Un
230 V L-N
Measured Voltage with
Over-range and Crest
Factor
80%-120% of Un
Frequency Range
45~65Hz
Input- Current
Base Current
10A
Max. Current
100A
Min. Current
0.5A
Over current withstand
30 x Imax 0.01s
Auxiliary Power
Supply
Operating Range
Self powered
Power Consumption
<2W/10VA
Frequency
50/60 Hz

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Digital output
Pulse output 1
0.001/0.01/0.1/1kWh/kVarh(configurable)
Pulse output 2
400imp/kWh(non-configurable)
Mechanical Characteristics
Weight
350g
IP Degree of Protection
(IEC 60529)
IP51 for front display;
IP20 for others
Dimensions (WxHxD)
72x100x66mm
Material of meter case
UL 94-V0
Environmental Characteristics
Operating Temperature
-25 ~ 55°C
Storage Temperature
-40 ~ 70°C
Humidity Rating
≤90% (non-condensing)
Pollution Degree
2
Altitude
<2000m
EMC
Electrostatic Discharge
IEC 61000-4-2
Immunity to Radiated Fields
IEC 61000-4-3
Immunity to Fast Transients
IEC 61000-4-4
Immunity to Impulse Waves
IEC 61000-4-5
Conducted Immunity
IEC 61000-4-6
Immunity to Magnetic Fields
IEC 61000-4-8
Immunity to Voltage Dips
IEC 61000-4-11
Radiated Emissions
CISPR 11 Class B
Conducted Emissions
CISPR 11 Class B
Harmonics
IEC 61000-3-2
Safety
Measurement Category
Per IEC61010-1
CAT III
Over voltage Category
CAT III
Communications
Interface standard and protocol
RS485 and MODBUS RTU
Communication address
1~247
Transmission mode
Half duplex
Transmission distance
1000m Maximum

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Transmission speed
2400bps~38400bps
Parity
None (default), Odd, Even
Stop bits
1 or 2
Connection capacity of the terminals(voltage measurement)
Single-wire, multi-wire, finely stranded condu-
ctor
2.5-25mm2
Pin terminals,ferrules
2.5-25mm2
Tightening torque
2-3 Nm
Stripping length
15mm
Connection capacity of the terminals(RS485 and output)
Single-wire, multi-wire, finely stranded condu-
ctor
0.5-1.5mm2
Pin terminals,ferrules
0.5-1.5mm2
Tightening torque
0.2-0.25 Nm
Stripping length
7mm
Operating concept
There are several ways to program the Energy Meter 122 and retrieve measured values.
•Directly on the device using four buttons.
•Via the programming software of the EM configuration tools.
•Via the RS485 interface with the Modbus protocol. Data can be changed and retrieved with the help of
the Modbus address list (stored on the accompanying data carrier).
These operating instructions only describe the operation of the Energy Meter 122 using the 4 buttons. The
programming software of the EM configuration tools has its own “on- line help”.

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EM configuration tools
The Energy Meter 122 can be programmed and read with the EM configuration tools software. For this, a PC
must be connected to the RS485 interface of the Energy Meter 122 via an RS485 Modbus to TCP/IP gateway.
Connection options
Connection of Energy Meter 122 to PC via an EM220-RTU-4DI2DO-GW as a gateway:

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Assembly
Installation location
The Energy Meter 122 can be installed in control cabinets or in small distribution boards according to DIN
43880. It is mounted on a 35 mm mounting rail according to DIN EN 60715. It can be installed in any position.
35mm
DIN Rail
Fig.: Energy Meter 122 on mounting rail according to DIN EN 60715
Power supply
EM122 takes power from the voltage measurement port without additional power supply, to ensure that the
voltage of measurement port complies with the information on the nameplate!
•The supply voltage must be connected through a fuse according to the technical data.
•In building installations, the supply voltage must be provided with a disconnect switch or
circuit breaker.
•The disconnect switch must be attached near the device and must be easily accessible by
the user.
•The switch must be labelled as a separator for this device.
•Voltages that exceed the permissible voltage range can destroy the device.

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Voltage and current measurement inputs
When connecting the voltage and current measurement, the following must be observed:
Isolation device
•A suitable circuit breaker must be fitted to disconnect and deenergize the Energy Meter 122.
•The circuit breaker must be placed in the vicinity of the Energy Meter 122, be marked for the user and
easily accessible.
•The circuit breaker must be UL/IEC certified.
Overcurrent protection device
•An overcurrent protection device must be used for line protection.
•For line protection, we recommend an overcurrent protection device as per the technical
specifications.
•The overcurrent protection device must be suitable for the line cross section used.
•The overcurrent protection device must be UL/IEC certified.
•A circuit breaker can be used as an isolating and line protection device. The circuit breaker must be
UL/IEC certified.
Fig.: Connection example for the voltage and measurement

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Attention!
The voltage and current should not exceed the allowable range.
Attention!
The Energy Meter 122 is not suitable for the measurement of DC voltages.
Attention!
The voltage measurement inputs on the Energy Meter 122 are dangerous to touch!
The attached screw terminal has to be fixed sufficiently with the screws on the device!
Direction of the current
Please wire in strict accordance with the current direction. If the connection is reversed, rewire it!
RS485 interface
The RS485 interface is designed with the Energy Meter 122 as a 3-pole contact and communicates via the
Modbus RTU protocol (please see the registers address list of Modbus RTU protocol ).
Fig.: RS485 interface, 3-pole contact
Fig.: RS485 interface, 3-pole contact with terminating resistor

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Terminating resistors
The cable should be terminated with resistors (120 ohm 1/4 W) at the beginning and end of a segment if the
communication distance larger than 300m.
The Energy Meter 122 has no terminating resistors.
Shielding
A twisted and shielded cable must be provided for connections via the RS485 interface.
•Ground the shields of all cables that run into the cabinet at the cabinet entry.
•Connect the shield so it has a large contact area and conductively with a low-noise earth.
•Mechanically trap the cable above the earthing clamp in order to avoid damage from cable movement.
•Use the appropriate cable inlets, e.g. PG screw joints, to insert the cable into the switch cabinet.

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Fig.: Shielding design for cabinet entry
Cable type
The cable used must be suitable for an ambient temperature of at least 80 °C.
For the wiring of the Modbus connection, CAT cables are not suitable. Please use the
recommended cables.
Maximum cable length
Max 1000m.
Bus structure
•All devices are connected in a bus structure (line) and each device has its own address within the bus (also
see programming parameters).
•Up to 32 stations can be interconnected in one segment.
•The cable is terminated with resistors (bus termination, 120 ohm 1/4 W) at the beginning and end of a
segment.
•If there are more than 32 stations, repeaters (line amplifiers) must be used in order to connect the
individual segments.
•Devices with activated bus termination must be supplied with power.
•It is recommended to set the master at the end of a segment.
•The bus is inoperative if the master is replaced with an activated bus termination.
•The bus can become unstable if the slave is replaced with an activated bus termination or is dead.
•Devices that are not involved in the bus termination can be exchanged without making the bus unstable.
•The shield has to be installed continuously and needs to be broadly and well conducting connected to an
external low voltage (or potential) ground at the end.
Fig.: Diagram of RS485 bus structure

- 19

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Pulse Output
The meter is equipped with 2 pulse outputs, which are fully isolated from the inside circuit:
•That generates pulses in proportion to the measured energy.
•The digital outputs are not short circuit protected.
•An external auxiliary voltage with overcurrent protective device is required, voltage range is 5-27VDC.
•The maximum input current shall be 27mA.
•Connected cables longer than 30 m must be shielded.
•Pulse output 1 is configurable.
•Pulse output 2 is non-configurable. It is fixed up with total kWh. The constant is 400imp/kWh.
+-
Uimp
R
O U T P U T
Fig.: Connection of digital outputs
Pules output must be fed as shown in the wiring diagram. Scrupulousil respect polarities and
the connection mode.