Energy Management Energy Meter Type EM21 72D
Class B (kWh) according to EN50470-3 Class 1 (kWh) according to EN62053-21 Class 2 (kvarh) according to EN62053-23 Accuracy 0.5 RDG (current/voltage) Energy meter Instantaneous variables readout: 3 DGT Energies readout: 6+1 DGT System variables: W, var, PF, Hz, Phase-sequence. Single phase variables: VLL, VLN, A, PF Energy measurements: total kWh and kvarh TRMS measurements of distorted sine waves (voltages/currents) Self power supply Dimensions: 4-DIN modules and 72x72mm Protection degree (front): IP50 Application adaptable display and programming procedure (Easyprog function) Easy connections management Detachable display Multi-use housing: for both DIN-rail and panel mounting applications
Certified according to MID Directive, Annex "B" "Type examination" relevant to active electrical energy meters (see Annex MI-003), see option P below Certified according to MID Directive, Annex "B" + Annex "F" for legal metrology relevant to active electrical energy meters (see Annex MI-003), see option PF below.

Product Description

Three-phase energy meter with removable front LCD display unit. The same unit can be used either as a DIN-rail mounting or a panel mounting energy meter. This general purpose threephase energy meter is suitable for both active and reactive energy metering for cost allocation but also for main electrical parameter measurement and retransmission (transducer function). Housing for DINrail mounting with IP50 (front) protection degree. Current measurements carried out by means of external current transformers and voltage measurements carried out either by means of direct connection or by means of potential transformers. EM21-72D is provided, as standard, with a pulsating output for active energy retransmission. In addition a 2-wire RS485 communication port is available as an option.
How to order EM21 72D AVX O X X
Model Range code System Power supply Output 1 Output 2 Option

Type Selection

Range codes AV5 (*): 400VLL AC, 5(6)A or 1(6)A (***) (CT connection) AV6 (**):120VLN/230VLL AC 5(6)A or 1(6)A (***) (VT/PT and CT connections) System 3 (*): balanced and unbalanced load: 3-phase, 4-wire; 3-phase, 3-wire; 2-phase, 3-wire; 1-phase, 2-wire Power supply X (*): Self power supply from 18V to 260VAC VLN, 45 to 65 Hz (connection VL1-N) Options X (*): P: None Certified according to MID Directive, Annex "B" "Type examination" relevant to active electrical energy meters (see Annex MI-003) (*) Certified according to MID Directive, Annex "B" + Annex "F" for legal metrology relevant to active electrical energy meters (see Annex MI-003) (**)
PF: (*) as standard. (**) on request. (***) the range 1(6)A is available but not in compliance with the EN50470-3 standard.
Output 2 X (*): None S (**): RS485 port
Output 1 O (*): Single static output (opto-mosfet)
Specifications are subject to change without notice

EM2172D DS ENG 190210

EM21 72D

Input specifications

Rated inputs Current type System type: 3 Not isolated (shunt inputs). Note: the external current transformers can be connected to earth individually. AV5 and AV6: 5(6)A. The 1(6)A range is available but not in compliance with the EN50470-3 standard. AV5: 400VLL; AV6: 120/230VLL In: see below, Un: see below In: 5A, Imax: 6A; Un: 160 to 260VLN (277 to 450VLL). In: 5A, Imax: 6A; Un: 40 to 144VLN (70 to 250VLL). From 0.002In to 0.2In: (0.5% RDG +3DGT). From 0.2In to Imax: (0.5% RDG +1DGT). In the range Un: (0,5% RDG +1DGT). In the range Un: (1% RDG +1DGT). Range: 45 to 65Hz; resolution: 1Hz (1%RDG +2DGT). [0.001+1%(1.000 - PF RDG)]. (2%RDG +2DGT). class B according to EN50470-1-3; class 1 according to EN62053-21. class 2 according to EN62053-23. In: 5A, Imax: 6A; 0.1 In: 0.5A. Start up current: 10mA. According to EN62053-21, EN50470-1-3, EN62053-23 200ppm/C. 1600 samples/s @ 50Hz, 1900 samples/s @ 60Hz 1 second 2 lines 1st line: 7-DGT, 2nd line: 3-DGT or 1st line: 3-DGT + 3-DGT, 2nd line: 3-DGT. LCD, h 7mm. 3-DGT. Energies Overload status Imported Total: 6+1DGT or 7DGT EEE indication when the value being measured is exceeding the Continuous inputs overload (maximum measurement capacity) Max. instantaneous variables: 999; energies: 999 999.9 or 999. Min. instantaneous variables: 0; energies 0.0. Red LED (Energy consumption) 0.001 kWh by pulse if CT ratio x VT ratio is <7; 0.01 kWh by pulse if CT ratio x VT ratio is 7.0 < 70.0; 0.1 kWh by pulse if CT ratio x VT ratio is 70.0 < 700.0; 1 kWh by pulse if CT ratio x VT ratio is 700.0; 16Hz, according to EN50470-3 Green LED (on the terminal blocks side) for power on (steady) and communication status: RX-TX (in case of RS485 option only) blinking. See List of the variables that can be connected to: TRMS measurements of distorted wave forms. By means of external CTs. In 5A: 3 (15A max. peak). 6A, @ 50Hz. 120A, @ 50Hz. 1.2 Un 2 Un < 0.3VA Power consumption: <2VA. 45 to 65 Hz. Two push buttons for variable selection and programming of the instrument working parameters.

Current range (by CT)

Max. and Min. indication
Voltage (direct or by VT/PT) Accuracy (Display + RS485) (@25C 5C, R.H. 60%, 48 to 62 Hz) AV5 model AV6 model Current AV5, AV6 models
Phase-neutral voltage Phase-phase voltage Frequency Active power Power Factor Reactive power Active energy

Max frequency

Measurements Method Coupling type Crest factor Current Overloads Continuous For 500ms Voltage Overloads Continuous For 500ms Current input impedance 5(6)A Voltage input impedance Self-power supply Frequency Key-pad

Reactive energy

Energy additional errors Influence quantities Temperature drift Sampling rate Display refresh time Display
Type Instantaneous variables read-out

Output specifications

Pulse output Number of outputs Type on the instrument. 247, selectable by means of the front keypad MODBUS/JBUS (RTU) System and phase variables: see table List of variables. All the configuration parameters. 1 start bit, 8 data bit, no parity,1 stop bit. 9600 bits/s. 1/5 unit load. Maximum 160 transceiver on the same bus. By means of optocouplers, 4000 VRMS output to measuring input.
Pulse duration Output Load Insulation
1 Programmable from 0.01 to 9.99 kWh per pulses. Output connectable to the energy meters (kWh) 100ms < 120ms (ON), 120ms (OFF), according to EN62052-31. Static: opto-mosfet. VON 2.5 VAC/DC max. 70 mA, VOFF 260 VAC/DC max. By means of optocouplers, 4000 VRMS output to measuring inputs. Multidrop, bidirectional (static and dynamic variables) 2-wire. Max. distance 1000m, termination directly
Addresses Protocol Data (bidirectional) Dynamic (reading only) Static (reading and writing) Data format Baud-rate Driver input capability Insulation

RS485 Type Connections

Software functions
Password Numeric code of max. 3 digits; 2 protection levels of the programming data: Password 0, no protection; Password from 1 to 999, all data are protected By means of potentiometer (back-side of the display module) it is possible to lock the access to all the configuration parameters. Transformer ratio VT (PT) CT 1.0 to 99.9 / 100 to 999 / 1.00k to 6.00k 1.0 to 99.9 / 100 to 999 / 1.00k to 9.99k / 10.0k to 60.0k. The maximum power being measured cannot exceed 210 MW calculated as maximum input voltage and current, (see the Accuracy paragraph). The maximum VT by CT ratio is 48.600. For MID complaint applications the maximum power being measured is 25 MW. Up to 3 variables per page. See Display pages , 3 different set of variables available (see Display pages ) according to the metering function being selected. By means of the front keypad: total energies (kWh, kvarh). Wrong phase detection and displaying. For all the display selections, both energy measurements are dependent from the current direction, both power measurements are independent from the current direction. The power measurements are always positive.

1st level 2nd level Programming lock
System selection System 3-Ph.n unbalanced load 3-phase (4-wire) 3-phase (3-wire) System 3-Ph.1 balanced load 3-phase (3-wire) one current and 3-phase to phase voltage measurements. Note: the phase to phase voltage is calculated multiplying by 1.73 the virtual phase to neutral voltage. 3-phase (4-wire) one current and 3-phase to neutral voltage measurements. Note: the phase to phase voltage is calculated multiplying by 1.73 the virtual phase to neutral voltage. 3-phase (2-wire) one current and 1-phase (L1) to neutral voltage measurement. 2-phase (3-wire) System 2-Ph System 1-Ph 1-phase (2-wire)

Displaying

Easy connection function

General specifications

Operating temperature -25C to +55C (-13F to 131F) (R.H. from 0 to 90% non-condensing @ 40C) according to EN62053-21 and EN62053-23. -30C to +70C (-22F to 158F) (R.H. < 90% noncondensing @ 40C) according to EN62053-21 and EN62053-23. Cat. III (IEC60664, EN60664). 4000 VRMS between measuring inputs and digital output. 4000 VRMS for 1 minute. 100 dB, 48 to 62 Hz. According to EN62052-11 15kV air discharge; Test with current: 10V/m from 80 to 2000MHz; Test without any current: 30V/m from 80 to 2000MHz; On current and voltage measuring inputs circuit: 4kV 10V/m from 150KHz to 80MHz Surge Radio frequency suppression Standard compliance Safety Metrology Pulse output Approvals Connections Cable cross-section area On current and voltage measuring inputs circuit: 6kV; According to CISPR 22 IEC60664, IEC61010-1 EN60664, EN61010-1 EN62052-11 EN62053-21, EN62053-23, EN50470-3 DIN43864, IEC62053-31 CE, cULus listed Screw-type 2.4 x 3.5 mm Min./Max. screws tightening torque: 0.4 Nm / 0.8 Nm 72 x 72 x 65 mm Noryl PA66, self-extinguishing: UL 94 V-0 Panel and DIN-rail IP50 IP20 Approx. 400 g (packing included)

Storage temperature

Installation category Insulation (for 1 minute)
Dielectric strength Noise rejection CMRR EMC Electrostatic discharges Immunity to irradiated Electromagnetic fields Burst Immunity to conducted disturbances
Housing Dimensions (WxHxD) Material Mounting Protection degree Front Screw terminals Weight
Power supply specifications
Self power supply 18 to 260VAC (48-62Hz). Across input VL1 and N Power consumption 2VA/1W
Insulation between inputs and outputs
Measuring Inputs Measuring Inputs
Opto-Mosfet output 4kV 4kV
Communication port 4kV 4kV
Self power supply 0kV 4kV 4kV -

4kV 4kV 0kV

Opto-Mosfet output Communication port

Self power supply

NOTE: all the models have, mandatorily, to be connected to external current transformers.
Accuracy (According to EN50470-3 and EN62053-23)
kWh, accuracy (RDG) depending on the current Percentage error limits for class index B +1,5% +1% 0% -1% -1,5% PF=1 PF=L0.5 to C0.8 0.05A(Imin) 0.25A(Itr) 0.25A(Itr) 5A (In) 5A (In) 6A (Imax) 6A (Imax) +2,5% +2% 0% -2% -2,5% sin=1 0.1A sin=0.5 0.25A 0.25A 0.5A 5A (In) 5A (In) 6A (Imax) 6A (Imax) kvarh, accuracy (RDG) depending on the current Percentage error limits
Accuracy limits (Active energy) Start-up current: 10mA
Accuracy limits (Reactive energy) Start-up current: 10mA
MID Annex MI-003 compliance
Accuracy 0.9 Un U 1.1 Un; 0.98 fn f 1.02 fn; fn: 50Hz; cos: 0.5 inductive to 0.8 capacitive. Class B I st: 0.01A; I min: 0.05A; I tr: 0.25A; I n: 5A I max: 6A. -25C to +55C (-13F to 131F) (R.H. from 0 to 90% non-condensing @ 40C) E2

Operating temperature

EMC compliance
Used calculation formulas
Phase variables Instantaneous effective voltage System variables Equivalent three-phase voltage Three-phase power factor (TPF)
Instantaneous active power
Voltage asymmetry Energy metering
Instantaneous power factor
Instantaneous effective current Where: i= considered phase (L1, L2 or L3) P= active power; Q= reactive power; t1, t2 =starting and ending time points of consumption recording; n= time unit;t= time interval between two successive power consumptions; n1, n2 = starting and ending discrete time points of consumption recording
Instantaneous apparent power Three-phase active power Instantaneous reactive power
Three-phase apparent power
List of the variables that can be connected to:
RS485 communication port Pulse outputs (only energies) 1-ph. sys. x x o x o o o o o o x o o x x o o x x o o x x o o x x o o x o 2-ph. sys. x x x x x o x x o o x x o x x x o x x x o x x x o x x x o x o 3-ph. 4-wire balanced system x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 3-ph. 3-wir balanced system x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 3-ph. 4-wire unbalanced system x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 3-ph. 3-wir unbalanced system x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x
Variable kWh kvarh V L-N sys (1) V L1 V L2 V L3 V L-L sys (1) V L1-2 V L2-3 V L3-1 A L1 A L2 A L3 VA sys (1) VA L1 (1) VA L2 (1) VA L3 (1) var sys var L1 (1) var L2 (1) var L3 (1) W sys W L1 (1) W L2 (1) W L3 (1) PF sys PF L1 PF L2 PF L3 Hz Phase sequence
Notes Total Total sys=system ()

sys=system ()

(x) = available (o) = not available (zero indication on the display) (1) = Variable available only through the serial communication port RS485

Display pages

No 1st variable (1st half-line) 2nd variable (2nd half-line) Phase sequence 7 PF L1 A L1 V L1-2 V L1 Total kWh Total kvarh PF sys PF L2 A L2 V L2-3 V L2 W sys kvar sys Hz PF L3 A L3 V L3-1 V L3

3rd variable (2nd line)

Note The phase sequence triangle appears in any page only if there is a phase reverse
Applications A B C x x x x x x x x x x x x x x
Indication of C, -C, L, -L depending on the quadrant Indication of C, -C, L, -L depending on the quadrant
Additional available information on the display
Type Meter information 1 Meter information 2 Meter information 3 Meter information 4 Meter information 5 Meter information 6 Meter information 7
1st line Y. 2007 value SYS [3P.n] Ct rAt. Ut rAt. PuLSE (kWh) Add
2nd line r.A0 LEd (kWh) value value value value value
note Year of production and firmware release KWh per pulse of the LED System type and connection type Current transformer ratio Voltage transformer ratio Pulse output: kWh per pulse Serial communication address
List of selectable applications
Description A B C Active energy meter Active and reactive energy meter Full set of variables Notes Active energy measurement with some minor parameters Active and reactive energy measurement with some minor parameters Full set of available variables can be displayed
One instrument with double mounting capability
By means of the patented detachable display it is possible to configure the same instrument either as a panel mounting meter or.
. as DIN-rail mounting meter.

Wiring diagrams

(6A) Self power supply, system type selection: 3P.n 3-ph, 4-wire, unbalanced load Fig. 1 3-ph, 4-wire, unbalanced load Fig. 2

6A inputs

V inputs

R S4 85

St at ic

ou tp ut

3-CT connection
3-CT and 3-VT/PT connections
(6A) System type selection: 3P.n 3-ph, 3-wire, unbalanced load Fig. 3 3-ph, 3-wire, unbalanced load Fig. 4 3-ph, 3-wire, unbalanced load Fig. 5
3-CT and 2-VT/PT connections

2-CT connections (ARON)

(6A) Self power supply, system type selection: 3P.1 3-ph, 3-wire, unbalanced load Fig. 6 3-ph, 3-wire, balanced load 1-CT connection Fig. 7 3-ph, 3-wire, balanced load Fig. 8
(*) NOTE: a 2-wire connection for voltage measurement is available accross 9 and 10.
2-CT and 2-VT/PT connections ARON
1-CT and 2-VT/PT connections
(*) NOTE: For a correct power supply of the instrument, the neutral must always be connected.
(6A) System type selection: 2P 2-ph, 3-wire Fig. 9 2-ph, 3-wire Fig. 10 (6A) System type selection: 1P 1-ph, 2-wire Fig. 11

2-CT connection

2-CT and 2-VT/PT connections

1-CT connection

Static output wiring diagram
(6A) System type selection: 1P 1-ph, 2-wire Fig. 12 Opto-mosfet

VDC/AC

1-CT and 1-VT connections

VDC/AC supply

RS485 port wiring diagram

RS485 port

16 B+ AB+ A14 B+ A-
RS485 NOTE: additional devices provided with RS485 are connected as per the picture above. The termination of the serial output is carried out only on the last instrument of the network, by means of a jumper between (B+) and (T).

Front panel description

1. Keypad To program the configuration parameters and scroll the variables on the display. 2. Pulse output LED Red LED blinking proportional to the energy being measured. 3. Display LCD-type with alphanumeric indications to display all the measured variables. 4. Connections Screw terminal blocks for instrument wiring. 5. Green LED Lit when power supply is available
Dimensions (DIN configuration)
Dimensions and panel cut out (72x72 panel mounting configuration)

68x68mm

-0 +0.7mm

COMMUNICATION PROTOCOL

Version 1 Revision 2 July 29th, 2010
1.1 1.2 Introduction.... 3 MODBUS functions.... 3
1.2.1 1.2.2 1.2.3 1.2.4 1.2.5
Function 03h (Read Holding Registers)...3 Function 04h (Read Input Registers)....4 Function 06h (Write Single Holding Register)...4 Function 08h (Diagnostic with sub-function code 00h)...5 Broadcast mode....5

Application notes..... 6

1.3.1 1.3.2 2
RS485 general considerations....6 MODBUS timing....6

TABLES.....7

Data format representation In Carlo Gavazzi instruments... 7

2.2 2.3 2.4 2.5 2.6 2.7

Geometric representation....7
Maximum and minimum electrical values in EM21... 7 Instantaneous variables and meters.... 8 Firmware version and revision code.... 8 Programming lock status.... 8 Carlo Gavazzi Controls identification code... 9 Programming parameter tables.... 9
2.7.1 2.7.2 2.7.3 2.7.4 2.7.5 2.7.6 2.7.7 2.7.8 2.7.9 3

3.1 3.2

Password configuration menu...9 Application menu....9 System configuration menu....9 PT and CT configuration menu....9 Pulse output configuration menu....10 Serial port configuration menu...10 Reset commands....10 Serial number....10 Note.....10

REVISIONS.....10

Modifications from Version 1 Revision 0... 10 Modifications from Version 1 Revision 1... 10

Energy management

Introduction
The RS485 serial interface supports the MODBUS/JBUS (RTU) protocol. In this document only the information necessary to read/write from/to EM21 has been reported (not all the parts of the protocol have been implemented). For a complete description of the MODBUS protocol please refer to the Modbus_Application_Protocol_V1_1a.pdf document that is downloadable from the www.modbus.org web site. 1.2 MODBUS functions
These functions are available on EM21: Reading of n Holding Registers (code 03h) Reading of n Input Register (code 04h) Writing of one Holding Registers (code 06h) Diagnostic (code 08h with sub-function code 00h) Broadcast mode (writing instruction on address 00h) IMPORTANT: 1) In this document the Modbus address field is indicated in two modes: 1.1) Modicom address: it is the 6-digit Modicom representation with Modbus function code 04 (Read Input Registers). It is possible to read the same values with function code 03 (Read Holding Registers) replacing the first digit (3) with the number 4. 1.2) Physical address: it is the word address value to be included in the communication frame. 2) The functions 03h and 04h have exactly the same effect and can be used indifferently. 3) The communication parameters are to be set according to the configuration of the instrument (refer to EM21 instruction manual) 1.2.1 Function 03h (Read Holding Registers) This function is used to read the contents of a contiguous block of holding registers (word). The Request frame specifies the starting register address and the number of registers to be read. It is possible to read maximum 11 registers (words) with a single request, when not differently specified. The register data in the response message are packed as two bytes per register (word), with the binary contents right justified within each byte. For each register, the first byte contains the high order bits (MSB) and the second contains the low order bits (LSB). Request frame
Description Physical address Function code Starting address Quantity of registers (N word) CRC Length 1 byte 1 byte 2 bytes 2 bytes 2 bytes Value 1 to F7h (1 to 247) 03h 0000h to FFFFh 1 to 10h (1 to 11) Note
Byte order: MSB, LSB Byte order: MSB, LSB
Response frame (correct action)
Description Physical address Function code Quantity of requested bytes Register value CRC Length 1 byte 1 byte 1 byte N*2 bytes 2 bytes Value 1 to F7h (1 to 247) 03h N word * 2 Byte order: MSB, LSB Note
EM21-DIN Communication Protocol
Response frame (incorrect action)
Description Physical address Function code Exception code CRC Length 1 byte 1 byte 1 byte 2 bytes Value 1 to F7h (1 to 247) 83h 01h, 02h, 03h, 04h (see note) Note Possible exception : 01h: illegal function 02h: illegal data address 03h: illegal data value 04h: slave device failure
1.2.2 Function 04h (Read Input Registers) This function code is used to read the contents of a contiguous block of input registers (word). The Request frame specifies the starting register address and the number of registers to be read. It is possible to read maximum 11 register (word) with a single request, when not differently specified. The register data in the response message are packed as two bytes per register (word), with the binary contents right justified within each byte. For each register, the first byte contains the high order bits (MSB) and the second contains the low order bits (LSB). Request frame

Description Physical address Function code Starting address Quantity of registers (N word) CRC Length 1 byte 1 byte 2 bytes 2 bytes 2 bytes Value 1 to F7h (1 to 247) 04h 0000h to FFFFh 1 to 10h (1 to 11) Note
Description Physical address Function code Quantity of requested bytes Register value CRC Length 1 byte 1 byte 1 byte N*2 bytes 2 bytes Value 1 to F7h (1 to 247) 04h N word * 2 Byte order: MSB, LSB Note
Description Physical address Function code Exception code CRC Length 1 byte 1 byte 1 byte 2 bytes Value 1 to F7h (1 to 247) 84h 01h, 02h, 03h, 04h Note Possible exception : 01h: illegal function 02h: illegal data address 03h: illegal data value 04h: slave device failure
1.2.3 Function 06h (Write Single Holding Register) This function code is used to write a single holding register. The Request frame specifies the address of the register (word) to be written and its content. The correct response is an echo of the request, returned after the register content has been written. Request frame
Description Physical address Function code Starting address Register value CRC Length 1 byte 1 byte 2 bytes 2 bytes 2 bytes Value 1 to F7h (1 to 247) 06h 0000h to FFFFh 0000h to FFFFh Note
Description Physical address Function code Exception code CRC Length 1 byte 1 byte 1 byte 2 bytes Value 1 to F7h (1 to 247) 86h 01h, 02h, 03h, 04h Note Possible exception : 01h: illegal function 02h: illegal data address 03h: illegal data value 04h: slave device failure
1.2.4 Function 08h (Diagnostic with sub-function code 00h) MODBUS function 08h provides a series of tests to check the communication system between a client (Master) device and a server (Slave), or to check various internal error conditions in a server. EM24-DIN supports only 0000h sub-function code (Return Query Data). With this sub-function the data passed in the request data field is to be returned (looped back) in the response. The entire response message should be identical to the request. Request frame
Description Physical address Function code Sub-function Data (N word) CRC Length 1 byte 1 byte 2 bytes N *2 bytes 2 bytes Value 1 to F7h (1 to 247) 08h 0000h Data Note

Byte order: MSB, LSB

Description Physical address Function code Sub-function Data (N word) CRC Length 1 byte 1 byte 2 bytes N *2 bytes 2 bytes Value 1 to F7 (1 to 247) 08h 0000h Data Note
Description Physical address Function code Exception code CRC Length 1 byte 1 byte 1 byte 2 bytes Value 1 to F7h (1 to 247) 88h 01h, 02h, 03h, 04h Note Possible exception : 01h: illegal function 02h: illegal data address 03h: illegal data value 04h: slave device failure

Broadcast mode

In broadcast mode the master can send a request (command) to all the slaves. No response is returned to broadcast requests sent by the master. It is possible to send the broadcast message only with function code 06h using address 00h.

1.3 1.3.1

Application notes RS485 general considerations
1. To avoid errors due to the signal reflections or line coupling, it is necessary to terminate the bus at the beginning and at the end (inserting a 120 ohm 1/2W 5% resistor between line B and A in the last instrument and in the Host interface). 2. The network termination is necessary even in case of point-to-point connection and/or of short distances. 3. For connections longer than 1000m or if in the network there are more than 160 instruments (with 1/5 unit load as used in EM21 interface), a signal repeater is necessary. 4. For bus connection it is suggested to use an AWG24 balanced pair cable and to add a third wire for GND connection. Connect GND to the shield if a shielded cable is used. 5. The GND is to be connected to ground only at the host side. 6. If an instrument does not answer within the max answering time, it is necessary to repeat the query. If the instrument does not answer after 2 or 3 consecutive queries, it is to be considered as not connected, faulty or reached with a wrong address. The same consideration is valid in case of CRC errors or incomplete response frames.

MODBUS timing

Fig. 1 : 2-wire timing diagram
Timing characteristics of reading function: T response: Max answering time T response: Typical answering time T delay: Minimum time before a new query T null: Max interruption time during the request frame
msec 500ms 40ms 3,5char 2,5char

2 TABLES

2.1 Data format representation In Carlo Gavazzi instruments
The variables are represented by integers or floating numbers, with 2s complement notation in case of signed format, using the following:
Format INT16 UINT16 INT32 UINT32 UINT64 IEEE754 SP IEC data type INT UINT DINT UDINT ULINT Description Integer Unsigned integer Double integer Unsigned double int Unsigned long integer Single-precision floating-point Bits Range -32768. 32767 0. 65535 -231. 231 0. 232-1 0. 264-1 -(1+[1 2-23])x2127. 2128

For all the formats the byte order (inside the single word) is MSB->LSB. In INT32, UINT32 and UINT64 formats, the word order is LSW-> MSW.
2.1.1 Geometric representation According to the signs of the power factor , the active power P and the reactive power Q, it is possible to obtain a geometric representation of the power vector, as indicated in the drawing below, according to EN 60253-23:
a = Exported active power b = Imported active power c = Imported reactive power d = Exported reactive power
Fig. 2 : Geometric Representation
Maximum and minimum electrical values in EM21
The maximum electrical input values are reported in the following table. If the input is above the maximum value the display shows EEE.

Table 2.1-1

VL-N VL-L A VT CT AV5 input option Max value Min value 485V 0 840V 0 6,5A 1.1.0 AV6 input option Max value Min value 150V 0 260V 0 6,5A 1.1.0
The overflow indication EEE is displayed when the MSB value of the relevant variable is 7FFFh.

Modicom address 300050

Instantaneous variables and meters

Table 2.3-1

Data Format INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT32 INT16 INT16 INT16 INT16 Notes Physical address 0000h 0002h 0004h 0006h 0008h 000Ah 000Ch 000Eh 0010h 0012h 0014h 0016h 0018h 001Ah 001Ch 001Eh 0020h 0022h 0024h 0026h 0028h 002Ah 002Ch 002Eh 002Fh 0030h 0031h Length (words) 1 VARIABLE ENG. UNIT V L1-N V L2-N V L3-N V L1-L2 V L2-L3 V L3-L1 A L1 A L2 A L3 W L1 W L2 W L3 VA L1 VA L2 VA L3 VAR L1 VAR L2 VAR L3 V L-N V L-L W VA VAR PF L1 PF L2 PF L3 PF
MODBUS: read only mode with functions code 03 and 04

Value weight: Volt*10

Value weight: Ampere*1000 Value weight: Watt*10 Value weight: VA*10 Value weight: var*10 Value weight: Volt*10 Value weight: Watt*10 Value weight: VA*10 Value weight: var*10 Negative values correspond to lead(C), positive value correspond to lag(L) Value weight: PF*1000 The value 1 corresponds to L1-L3L2 sequence, the value 0 corresponds to L1-L2-L3 sequence. The phase sequence value is meaningful only in a 3-phase system Value weight: Hz Value weight: kWh*10 Value weight: kvarh*10

300051

Phase sequence

300055

0033h 0034h 0036h
Hz KWh(+) TOT Kvarh(+) TOT

INT16 INT32 INT32

Modicom address 300771 300772
Firmware version and revision code

Table 2.4-1

Notes Value=0: Version A Value=0: Revision 0 Physical address 0302h 0303h Length (words) VARIABLE ENG. UNIT Version code Revision code Data Format UINT 16 UINT 16
MODBUS: read only mode with functions code 03 and 04 limited to a word at a time

Modicom address 300773

Programming lock status

Table 2.5-1

Notes Value=1: programming locked Value=0: programming unlocked Physical address 0304h Length (words) 1 VARIABLE ENG. UNIT Programming lock (trimmer position in the rear of the display) Data Format UINT 16

Modicom address 300012

Carlo Gavazzi Controls identification code

Table 2.6-1

Notes Value=57: EM21 AV5 input model Value=58: EM21 AV6 input model Physical address 000Bh Length (words) 1 VARIABLE ENG. UNIT Carlo Gavazzi Controls identification code Data Format UINT 16

2.7 2.7.1

Programming parameter tables Password configuration menu

Table 2.7-1

VARIABLE ENG. UNIT PASSWORD Data Format UINT 16 Notes Minimum valid value: 0d Maximum valid value: 999d
MODBUS: read and write mode
Modicom address 304097 Physical address 1000h Length (words) 1

Application menu

Table 2.7-2
VARIABLE ENG. UNIT Type of application Data Format UINT 16 Notes Value=0: A application Value=1: B application Value=2: C application
Modicom address 304098 Physical address 1001h Length (words) 1
System configuration menu

Table 2.7-3

VARIABLE ENG. UNIT Measuring system Data Format UINT 16 Notes Value=0: Value=1: Value=2: Value=3: Value=4: 3Pn 3P1 2P 1P 3P
Modicom address 304099 Physical address 1002h Length (words) 1
PT and CT configuration menu

Table 2.7-4

VARIABLE ENG. UNIT Current transformer ratio Voltage transformer ratio Data Format UINT 32 UINT 32 Notes Value Value Value Value min max min max = = = = 10 (CT=1,0) 600000 (CT=60000.0) 10 (VT=1,0) 60000 (VT=6000.0)

Modicom address Physical address 1003h 1005h Length (words) 2 2

Modicom address 304104

Pulse output configuration menu
Physical address 1007h Length (words) 1 VARIABLE ENG. UNIT Kwh per pulse Data Format UINT 16 Notes Value min = 1 (0,01Kwh) Value max = 999 (9,99KWh)
MODBUS: read read and write mode
Serial port configuration menu

Table 2.7-5

VARIABLE ENG. UNIT RS485 instrument address Data Format UINT 16 Notes Value min = 1 Value max = 247
Modicom address 304105 Physical address 1008h Length (words) 1
Note: The number of stop bits is fixed to 1 and the parity control is fixed to none.

Reset commands

Table 2.7-12
VARIABLE ENG. UNIT Reset of all meters (KwhTOT and KvarhTOT) Data Format UINT 16 Notes Value=1: Command is executed All other values produce no effects

MODBUS: write only mode

Modicom address 312289 Physical address 3000h Length (words) 1

Serial number

Table 2.7-13
VARIABLE ENG. UNIT Instrument serial number Data Format UINT 16 Notes

MODBUS: read only mode

Modicom address 320481 Physical address 5000h Length (words) 7
2.7.9 Note A default value is not automatically assignes to the parameters when an out-of-range or invalid value is written. If an invalid value is assigned to any parameter, the unit could not work properly.

3 REVISIONS

This is the first release of the EM21 communication protocol 3.1 Modifications from Version 1 Revision 0
The frequency value doesnt has to multiplied by 10 (see par. 2.3, tab 2.3.1)
Modifications from Version 1 Revision 1
Added serial number reading