Satec expertmeter EM720 User manual

Power Quality and Revenue Meter
EM720/EM720T
Modbus Communications Protocol
Reference Guide
BG0457 Rev. A8

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Every effort has been made to ensure that the material herein is complete and accurate.
However, the manufacturer is not responsible for any mistakes in printing or faulty
instructions contained in this book. Notification of any errors or misprints will be received
with appreciation.
For further information regarding a particular installation, operation or maintenance of
equipment, contact the manufacturer or your local representative or distributor.
REVISION HISTORY
A1 Feb 2009 Initial release
A2 July 2009 Added a selectable EN 50160 transient overvoltage detection method option
A3 Nov 2009 Added external tariff control options via communications and tariff inputs
A4 Jan 2011 Added TCP event notification client.
Added communication status and communication counters registers.
Added Transformer Correction and Transformer/Line Loss Compensation setups.
Added IEC 61850 Report Deadbands setup.
A5 Feb 2013 Added IEC 61850 GOOSE publisher, dataset setup and RCB setup registers.
A6 Oct 2014 Added EN 50160:2010 setup and compliance statistics files.
A7 Aug 2015 Added 3-second power and power factor readings.
Added cellular module’s mobile equipment identifier indication.
A8 Aug 2016 Added uncompensated power/energy registers.
Modbus is a trademark of Schneider Electric.

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Table of Contents
1GENERAL .............................................................................................. 9
2MODBUS PROTOCOL IMPLEMENTATION ............................................ 10
2.1 Transmission Modes..............................................................................................10
2.2 Address Field.........................................................................................................10
2.3 Function Field........................................................................................................10
2.4 Exception Responses.............................................................................................10
2.5 Modbus Register Addresses ..................................................................................10
2.6 Data Formats.........................................................................................................11
2.6.1 16-bit Scaled Integer Format .............................................................................11
2.6.2 32-bit Long Integer Format................................................................................12
2.6.3 32-bit Modulo-10000 Format..............................................................................13
2.7 User Assignable Registers.....................................................................................13
2.8 Password Protection .............................................................................................14
2.9 Data Recording and File Transfers ........................................................................14
2.9.1 Log File Organization ........................................................................................14
2.9.2 File Transfers...................................................................................................15
2.10 TCP Notification Client...........................................................................................18
3MODBUS REGISTER MAP .................................................................... 20
3.1 Modbus Setup Registers........................................................................................20
Modbus Assignable Registers................................................................................20
Assignable Registers Map.....................................................................................20
Modbus Conversion Scales ...................................................................................20
Device Data Scales .............................................................................................20
3.2 16-bit Scaled Analog Registers and Energy Counters - Basic Register Set ...........21
3.3 16-bit Scaled Analog Registers, Binary Registers and Counters...........................23
None.................................................................................................................23
Setpoint Status ..................................................................................................23
Special Inputs .................................................................................................... 23
Event Flags........................................................................................................23
Digital Inputs .....................................................................................................23
Relay Outputs ....................................................................................................23
Counters ...........................................................................................................23
1/2-Cycle Values ................................................................................................23
1-Cycle Phase Values ..........................................................................................24
1-Cycle Low Phase Values....................................................................................24
1-Cycle High Phase Values ...................................................................................25
1-Cycle Total Values............................................................................................25
1-Cycle Auxiliary Values.......................................................................................25
Phasor ..............................................................................................................26
1-Second Phase Values........................................................................................26
1-Second Low Phase Values .................................................................................27
3-Second Powers................................................................................................27
1-Second High Phase Values ................................................................................28
1-Second Total Values.........................................................................................28
1-Second Auxiliary Values....................................................................................28
Present Harmonic Demands .................................................................................29
Present Demands................................................................................................29
Instrumentation Total Energies.............................................................................30
Symmetrical Components ....................................................................................30
V1/V12 Harmonic Distortion.................................................................................31
V2/V23 Harmonic Distortion.................................................................................31
V3/V31 Harmonic Distortion.................................................................................31
I1 Harmonic Distortion ........................................................................................31
I2 Harmonic Distortion ........................................................................................31

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I3 Harmonic Distortions.......................................................................................31
I4 Harmonic Distortion ........................................................................................31
Fundamental Phase Values...................................................................................31
Flicker...............................................................................................................32
Fundamental Total Values ....................................................................................32
Minimum 1-Cycle Phase Values.............................................................................32
Minimum 1-Cycle Total Values .............................................................................. 33
Minimum 1-Cycle Auxiliary Values.........................................................................33
Maximum 1-Cycle Phase Values ............................................................................33
Maximum 1-Cycle Total Values .............................................................................34
Maximum 1-Cycle Auxiliary Values ........................................................................34
Instrumentation Maximum Demands .....................................................................34
Maximum Harmonic Demands ..............................................................................35
TOU Parameters .................................................................................................35
Billing TOU Energy Register #1.............................................................................35
Billing TOU Energy Register #2.............................................................................35
Billing TOU Energy Register #3.............................................................................35
Billing TOU Energy Register #4.............................................................................36
Billing TOU Energy Register #5.............................................................................36
Billing TOU Energy Register #6.............................................................................36
Billing TOU Energy Register #7.............................................................................36
Billing TOU Energy Register #8.............................................................................36
Billing TOU Energy Register #9.............................................................................36
Billing TOU Energy Register #10 ...........................................................................36
Billing Summary Accumulated Demands.................................................................36
Billing Summary Block Demands...........................................................................37
Billing Summary Sliding Window Demands .............................................................37
Billing Summary Maximum Demands.....................................................................37
Billing TOU Maximum Demand Register #1.............................................................37
Billing TOU Maximum Demand Register #2.............................................................37
Billing TOU Maximum Demand Register #3.............................................................37
Billing TOU Maximum Demand Register #4.............................................................37
Billing TOU Maximum Demand Register #5.............................................................37
Billing TOU Maximum Demand Register #6.............................................................37
Billing TOU Maximum Demand Register #7.............................................................38
Billing TOU Maximum Demand Register #8.............................................................38
Billing TOU Maximum Demand Register #9.............................................................38
Billing TOU Maximum Demand Register #10...........................................................38
V1/V12 Harmonic Angles .....................................................................................38
V2/V23 Harmonic Angles .....................................................................................38
V3/V31 Harmonic Angles .....................................................................................38
I1 Harmonic Angles.............................................................................................38
I2 Harmonic Angles.............................................................................................39
I3 Harmonic Angles.............................................................................................39
I4 Harmonic Angles.............................................................................................39
0.2-Second RMS Values.......................................................................................39
3-Second RMS Values..........................................................................................39
10-Minute RMS Values.........................................................................................40
0.2-Second Total Harmonics.................................................................................41
3-Second Total Harmonics ...................................................................................41
10-Minute Total Harmonics...................................................................................42
3.4 32-bit Analog Registers, Binary Registers and Counters ......................................44
Setpoint Status ..................................................................................................44
Special Inputs .................................................................................................... 44
Event Flags........................................................................................................44
Internal Pulsed Events.........................................................................................44
Digital Inputs .....................................................................................................44
Relay Outputs ....................................................................................................44
Internal Static Events..........................................................................................44
Counters ...........................................................................................................44
Time/Date .........................................................................................................44
1/2-Cycle Values ................................................................................................45

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1-Cycle Phase Values ..........................................................................................45
1-Cycle Low Phase Values....................................................................................46
1-Cycle High Phase Values ...................................................................................46
1-Cycle Total Values............................................................................................47
1-Cycle Auxiliary Values.......................................................................................47
Phasor ..............................................................................................................47
1-Second Phase Values........................................................................................48
1-Second Low Phase Values .................................................................................49
3-Second Powers................................................................................................49
1-Second High Phase Values ................................................................................49
1-Second Total Values.........................................................................................50
Uncompensated Total Energy ...............................................................................50
1-Second Auxiliary Values....................................................................................50
Present Harmonic Demands .................................................................................51
Present Demands................................................................................................51
Instrumentation Total Energies.............................................................................52
Billing Summary (Total) Energy Registers...............................................................52
Symmetrical Components ....................................................................................52
V1/V12 Harmonic Distortion.................................................................................53
V2/V23 Harmonic Distortion.................................................................................53
V3/V31 Harmonic Distortion.................................................................................53
I1 Harmonic Distortion ........................................................................................53
I2 Harmonic Distortion ........................................................................................53
I3 Harmonic Distortion ........................................................................................53
I4 Harmonic Distortion ........................................................................................53
Fundamental Phase Values...................................................................................53
Flicker...............................................................................................................54
Fundamental Total Values ....................................................................................54
Minimum 1-Cycle Phase Values.............................................................................54
Minimum 1-Cycle Total Values .............................................................................. 55
Minimum 1-Cycle Auxiliary Values.........................................................................55
Maximum 1-Cycle Phase Values ............................................................................55
Maximum 1-Cycle Total Values .............................................................................56
Maximum 1-Cycle Auxiliary Values ........................................................................56
Instrumentation Maximum Demands .....................................................................56
Maximum Harmonic Demands ..............................................................................57
TOU Parameters .................................................................................................57
Billing TOU Energy Register #1.............................................................................57
Billing TOU Energy Register #2.............................................................................57
Billing TOU Energy Register #3.............................................................................57
Billing TOU Energy Register #4.............................................................................58
Billing TOU Energy Register #5.............................................................................58
Billing TOU Energy Register #6.............................................................................58
Billing TOU Energy Register #7.............................................................................58
Billing TOU Energy Register #8.............................................................................58
Billing TOU Energy Register #9.............................................................................58
Billing TOU Energy Register #10 ...........................................................................58
Billing Summary Accumulated Demands.................................................................58
Billing Summary Block Demands...........................................................................59
Billing Summary Sliding Window Demands .............................................................59
Billing Summary (Total) Maximum Demands...........................................................59
Billing TOU Maximum Demand Register #1.............................................................59
Billing TOU Maximum Demand Register #2.............................................................59
Billing TOU Maximum Demand Register #3.............................................................60
Billing TOU Maximum Demand Register #4.............................................................60
Billing TOU Maximum Demand Register #5.............................................................60
Billing TOU Maximum Demand Register #6.............................................................60
Billing TOU Maximum Demand Register #7.............................................................61
Billing TOU Maximum Demand Register #8.............................................................61
Billing TOU Maximum Demand Register #9.............................................................61
Billing TOU Maximum Demand Register #10...........................................................61
V1/V12 Harmonic Angles .....................................................................................62

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V2/V23 Harmonic Angles .....................................................................................62
V3/V31 Harmonic Angles .....................................................................................62
I1 Harmonic Angles.............................................................................................62
I2 Harmonic Angles.............................................................................................62
I3 Harmonic Angles.............................................................................................62
I4 Harmonic Angles.............................................................................................62
0.2-Second RMS Values.......................................................................................62
3-Second RMS Values..........................................................................................63
10-Minute RMS Values.........................................................................................64
0.2-Second Total Harmonics.................................................................................64
3-Second Total Harmonics ...................................................................................65
10-Minute Total Harmonics...................................................................................65
Present EN 50160:2007 PQ Values ........................................................................66
Present EN 50160:2010 PQ Values ........................................................................67
Generic TOU Energy Registers ..............................................................................68
Generic TOU Maximum Demand Registers..............................................................68
Generic Data......................................................................................................68
3.5 Minimum/Maximum Log Registers .......................................................................71
Minimum Phase Values ........................................................................................71
Minimum Total Values .........................................................................................72
Minimum Auxiliary Values ....................................................................................72
Maximum Phase Values .......................................................................................73
Maximum Total Values.........................................................................................74
Maximum Auxiliary Values ...................................................................................75
Billing Summary Maximum Demands.....................................................................75
Engineering Maximum Demands ...........................................................................75
Maximum Harmonic Demands ..............................................................................76
Billing TOU Maximum Demand Register #1.............................................................77
Billing TOU Maximum Demand Register #2.............................................................77
Billing TOU Maximum Demand Register #3.............................................................77
Billing TOU Maximum Demand Register #4.............................................................77
Billing TOU Maximum Demand Register #5.............................................................77
Billing TOU Maximum Demand Register #6.............................................................77
Billing TOU Maximum Demand Register #7.............................................................78
Billing TOU Maximum Demand Register #8.............................................................78
Billing TOU Maximum Demand Register #9.............................................................78
Billing TOU Maximum Demand Register #10...........................................................78
3.6 Billing Period Data.................................................................................................79
Present billing period data....................................................................................79
Previous (most recent) billing period data...............................................................79
Second previous billing period data .......................................................................79
Third previous billing period data ..........................................................................79
Fourth previous billing period data ........................................................................79
3.7 Device Control and Status Registers .....................................................................88
User Event Flags Registers (bitmap)......................................................................88
Remote Relay Control Registers (bitmap) ...............................................................88
Reset/Clear Registers..........................................................................................88
Device Mode Control Registers..............................................................................89
Operation/Event Counters....................................................................................89
Memory Status Registers .....................................................................................89
Log Notification Registers.....................................................................................89
Setpoint Status Registers.....................................................................................89
Setpoint Alarm Latch Registers .............................................................................89
Device Diagnostics Register..................................................................................90
Current Port Number...........................................................................................90
Current Network Settings.....................................................................................90
Device Authorization Registers..............................................................................90
Communication Status.........................................................................................90
Communication Counters.....................................................................................91
Factory Diagnostic Registers.................................................................................91
3.8 Device Setup Registers..........................................................................................92
Device Identification............................................................................................92

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Factory Device Settings .......................................................................................92
Basic Setup........................................................................................................92
Demands Setup..................................................................................................93
Device Options Setup ..........................................................................................93
Local Settings ....................................................................................................94
Clock Indication and Setup...................................................................................94
Communication Ports Setup .................................................................................95
Network Setup ...................................................................................................95
Dial-up/GPRS Modem Setup.................................................................................95
Password Setup..................................................................................................96
IEC 61850 License Setup .....................................................................................96
Expert Power Service Setup .................................................................................96
Internet Service Provider (ISP) account .................................................................96
SNTP Client Setup...............................................................................................96
TCP Notification Client Setup ................................................................................97
Transformer Correction Setup...............................................................................97
Transformer/Line Loss Compensation Setup............................................................97
Display Setup.....................................................................................................98
GOOSE Publisher Setup .......................................................................................98
IEC 61850 IED Setup ..........................................................................................99
IEC 61850 Dataset Setup.....................................................................................99
IEC 61850 RCB Setup..........................................................................................99
IEC 61850 Report Deadbands............................................................................. 100
DNP Options Setup ........................................................................................... 100
DNP Events Setup............................................................................................. 101
DNP Class 0 Point Assignments........................................................................... 101
EN50160:2007 PQ Recorder Setup ...................................................................... 101
Advanced EN50160:2007 Setup.......................................................................... 102
EN50160:2010 PQ Recorder Setup ...................................................................... 103
Advanced EN50160:2010 Setup.......................................................................... 104
EN50160 Harmonic Voltage Limits....................................................................... 105
EN50160 Interharmonic Voltage Limits ................................................................ 105
Fault Log Triggers Setup.................................................................................... 105
Fault Log Recording Setup ................................................................................. 106
File Setup........................................................................................................ 106
Waveform Recorder Setup ................................................................................. 107
Data Log Setup ................................................................................................ 107
TOU Daily Profile Setup...................................................................................... 108
TOU Calendar Setup.......................................................................................... 109
Billing Energy/TOU Registers Setup ..................................................................... 109
Billing Energy/TOU Registers Source Setup........................................................... 110
Control Setpoints Setup..................................................................................... 110
Periodic Timers Setup........................................................................................ 111
Digital Inputs Setup .......................................................................................... 111
Relay Outputs Setup ......................................................................................... 112
3.9 Expansion I/O Configuration ..............................................................................113
I/O Slots Configuration Info................................................................................ 113
I/O Type Info................................................................................................... 113
3.10 File Transfer Registers ........................................................................................114
File Transfer Control Blocks................................................................................ 114
File Info Response Block (Variation 0 – File info) ................................................... 115
File Info Response Block (Variation 1 – Current record info).................................... 116
File Info Response Block (Variation 2 – Data log record structure)............................ 116
Event Log Response Block.................................................................................. 117
Data Log Response Block................................................................................... 117
Waveform Log Response Block............................................................................ 118
Power Quality (PQ) Log Response Block ............................................................... 118
Fault Log Response Block................................................................................... 119

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3.11 EN 50160:2007 Compliance Statistics Data Log..................................................121
3.12 EN 50160:2007 Harmonic Statistics Data Log.....................................................126
3.13 EN 50160:2010 Compliance Statistics Data Log..................................................128
3.14 EN 50160:2010 Harmonic Statistics Data Log.....................................................133
3.15 Billing/TOU Monthly Profile Data Log .................................................................137
3.16 Billing/TOU Daily Profile Data Log ......................................................................139
3.17 Energy Load Profile Data Log ..............................................................................140
4DATA SCALES AND UNITS ................................................................ 141
Data Scales ..................................................................................................... 141
Data Units ....................................................................................................... 141
5DATA FORMATS ................................................................................ 142
Timestamp ...................................................................................................... 142
File ID............................................................................................................. 142
File Attributes................................................................................................... 142
File Status Word (bitmap).................................................................................. 142
File Record Status Word (bitmap)........................................................................ 142
TOU Profile Log Channel ID ................................................................................ 142
Waveform Log Channel ID.................................................................................. 142
Profile Log Sections Mask................................................................................... 143
Waveform Log Channel Mask.............................................................................. 143
TOU Tariff Change Time..................................................................................... 143
Billing/TOU Register Source ID ........................................................................... 143
Setpoint Trigger Parameters ID........................................................................... 143
Setpoint Relational Operator............................................................................... 143
Setpoint Action ID............................................................................................. 143
Counter Source ID ............................................................................................ 144
Relay Output Pulse Source ID............................................................................. 144
AO Output Parameters ID .................................................................................. 144
Event Cause/Point ID ........................................................................................ 145
Event Effect ID................................................................................................. 145
Data Point ID ................................................................................................... 146
Event Type ID .................................................................................................. 146
Device Diagnostics (bitmap)............................................................................... 147
DNP Object Types............................................................................................. 147
DNP Class 0 Objects.......................................................................................... 148
Wiring Mode..................................................................................................... 148
Factory Device Options (bitmap)......................................................................... 148
IEC 61850 Measured Value Indices...................................................................... 149

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1 General
This document specifies a subset of the Modbus communications protocol used to
transfer data between a master computer station and the EM720. The document
provides the complete information necessary to develop third-party communications
software capable of communication with the EM720. Refer to the EM720 Installation
Manual and EM720 Operation Manual for more information on communication
connections and configuring communication parameters in your device.

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2 Modbus Protocol Implementation
For detailed information on the Modbus protocol, message framing and error checking,
refer to the Modbus Protocol Reference Guide. It can be downloaded from the Modbus-
IDA Website at http://www.modbus.org/. The following paragraphs outline some
issues concerning the implementation of the Modbus protocol in the EM720.
2.1 Transmission Modes
The EM720 can be set up to communicate on a serial Modbus network using either
RTU, or ASCII serial transmission mode, and via the Internet using Modbus/TCP mode.
Refer to the EM720 Operation Manual for information on selecting the transmission
mode in your meter.
2.2 Address Field
The address field contains a user assigned address of the instrument (1-247) on a
Modbus network. Broadcast mode using address 0 is not supported.
When communicating via the Internet, the address field is not checked and is returned
in the response message header.
2.3 Function Field
The Modbus functions implemented in the EM720 are shown in Table 2-1. Function 04
can be used in the same context as function 03.
Table 2-1 Modbus Function Codes
Code (decimal) Meaning in Modbus Action
03 Read holding registers Read multiple registers
04 Read input registers Read multiple registers
06 Preset single register Write single register
16 Preset multiple registers Write multiple registers
081Loop-back test Communications test
1 The EM720 supports only diagnostic code 0 - return query data.
2.4 Exception Responses
The instrument sends an exception response when an error is detected in the received
message. To indicate that the response is notification of an error, the high order bit of
the function code is set to 1.
Implemented exception response codes:
01 - Illegal function
02 - Illegal data address
03 - Illegal data value
04 - Device failure
When the character framing, parity, or redundancy check detects a communication
error, processing of the master's request stops. The instrument will not act on or
respond to the message.
2.5 Modbus Register Addresses
The EM720 Modbus registers are numbered in the range of 0 to 65535. From the
Modbus applications, the EM720 Modbus registers can be accessed by simulating
holding registers of the Modicon 584, 884 or 984 Programmable Controller, using a 5-
digit “4XXXX” or 6-digit “4XXXXX” addressing scheme.

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To map the EM720 register address to the range of the Modbus holding registers, add
a value of 40001 to the EM720 register address. When a register address exceeds
9999, use a 6-digit addressing scheme by adding 400001 to the EM720 register
address.
2.6 Data Formats
The EM720 uses three data formats to pass data between a master application and the
instrument: 16-bit short integer, 32-bit long integer and 32-bit modulo-10000 formats.
Binary values and counters are always transmitted in 32-bit registers, while analog
values can be read both in 32-bit and in 16-bit scaled registers.
Analog registers 256 through 308 and 6656 through 10935 contain scaled 16-bit
values.
2.6.1 16-bit Scaled Integer Format
16-bit scaled analog data is transmitted in a single 16-bit Modbus register being scaled
to the range of 0 to 9999. To get a true reading, a reverse conversion should be done
using the following formula:
LO
)LOHI(X
Y+
−×
=9999
where:
Y - True reading in engineering units
X - Raw input data in the range of 0 to 9999
LO and HI - Data low and high scales in engineering units
Refer to Section 4 “Data Scales and Units” for applicable data scales and measurement
units. The engineering scales are indicated for every scaled 16-bit register.
The default voltage scale in the device is 144V (120V+20%). It can be changed
through register 242 (see Section 3.1, Device Data Scales), or via the supplemental
PAS software. The recommended voltage scale is 120V+20% = 144V for using with
external PT’s, and 480V+25% = 600V for a direct connection to power line.
CONVERSION EXAMPLES
1. Voltage readings
a) Assume device settings (direct wiring): PT ratio = 1; Voltage scale = 600V (480V + 25%).
Voltage engineering scales (see Section 4):
HI_ENG = Vmax = 600.0 ×PT ratio = 600.0 ×1 = 600.0V
LO_ENG = 0V
If the raw data reading is 2000 then the voltage reading in engineering units will be as follows:
Volts reading = 2000 ×(600.0 - 0)/(9999 - 0) + 0 = 120.0V
b) Assume device settings (wiring via PT): PT ratio = 14,400V : 120V = 120; Voltage scale =
144V.
Voltage engineering scales (see Section 4):
HI_ENG = Vmax = 144.0 ×PT ratio = 144 ×120 = 17,280V
LO_ENG = 0V
If the raw data reading is 8314 then the voltage reading in engineering units will be as follows:
Volts reading = 8314 ×(17,280 - 0)/9999 + 0 = 14,368V
2. Current readings
Assume device settings: CT primary current = 200A.

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Current engineering scales (see Section 4):
HI_ENG = Imax = CT primary current ×2 = 200.00 ×2 = 400.00A
LO_ENG = 0A
If the raw data reading is 250 then the current reading in engineering units will be as follows:
Amps reading = 250 ×(400.00 - 0)/(9999 - 0) + 0 = 10.00A
3. Power readings
a) Assume device settings (direct wiring): Wiring 4LL3; PT = 1; CT primary current = 200A;
Voltage scale = 600V.
Active power engineering scales (rounded to whole kW, see Section 4):
HI_ENG = Pmax = Vmax ×Imax ×2 = (600.0 ×1) ×(200.00 ×2) ×2 = 480,000 W = 480 kW
LO_ENG = -Pmax = -480 kW
If the raw data reading is 5500 then the power reading in engineering units will be as follows:
Watts reading = 5500 ×(480 - (-480))/(9999 - 0) + (-480) = 48.1 kW
If the raw data reading is 500 then the power reading in engineering units will be as follows:
Watts reading = 500 ×(480 - (-480))/(9999 - 0) + (-480) = -432.0 kW
b) Assume device settings (wiring via PT): Wiring 4LN3; PT = 120; CT primary current = 200A.
Active power engineering scales (rounded to whole kW, see Section 4):
HI_ENG = Pmax = Vmax ×Imax ×3 = (600 ×120) ×(200.00 ×2) ×3/1000 = 86,400 kW
LO_ENG = -Pmax = -86,400 kW
If the raw data reading is 5500 then the power reading in engineering units will be as follows:
Watts reading = 5500 ×(86,400 - (-86,400))/(9999 - 0) + (-86,400) = 8,650 kW
If the raw data reading is 500 then the power reading in engineering units will be as follows:
Watts reading = 500 ×(86,400 - (-86,400))/(9999 - 0) + (-86,400) = -77,759 kW
4. Power Factor readings
Power factor engineering scales (see Section 3.3):
HI_ENG = 1.000.
LO_ENG = -1.000.
If the raw data reading is 8900 then the power factor in engineering units will be as follows:
Power factor reading = 8900 ×(1.000 - (-1.000))/(9999 - 0) + (-1.000) = 0.78
2.6.2 32-bit Long Integer Format
32-bit long integer data is transmitted in two adjacent 16-bit Modbus registers as
unsigned (UINT32) or signed (INT32) whole numbers. The first register contains the
low-order word (lower 16 bits) and the second register contains the high order word
(higher 16 bits). The low-order word always starts at an even Modbus address.
The value range for unsigned data is 0 to 4,294,967,295; for signed data the range is -
2,147,483,648 to 2,147,483,647.
If your Modbus driver does not support a 32-bit long integer format, you can read the
two 16-bit registers separately, and then convert them into a 32-bit value as follows
(using C notation):
32-bit value = (signed short) high_order_register ×65536L + (unsigned short) low_order_register
EXAMPLES
1. Unsigned 32-bit Values
If you read unsigned Voltage V1 of 69,000V from registers 13952-13953, then the register
readings will be as follows:

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(13952) = 3464
(13953) = 1
The 32-bit value is (1 x 65536 + 3464) = 69000V.
2. Signed 32-bit Values
If you read signed kW of -789kW from registers 14336-14337, then the register readings will be:
(14336) = 64747 (unsigned)
(14337) = 65535 (unsigned) or -1(signed value).
To take the high order register as a signed value, compare it with 32767. If the value is less or
equal to 32767, use it as is. If it is greater than 32767, then this is a negative number in a two's
complement code (like in our example) - just subtract it from 65536 to get the original negative
value.
The 32-bit reading is (-1 x 65536 + 64747) = -789kW.
Fractional 32-bit data is transmitted using a decimal pre-multiplier to pass fractional
numbers in an integer format. Fractional numbers are pre-multiplied by 10 to the
power N, where N is the number of digits in the fractional part. For example, the
frequency reading of 50.01 Hz is transmitted as 5001, having been pre-multiplied by
100.
Whenever a data register contains a fractional number, the register measurement unit
is given with a multiplier ×0.1, ×0.01 or ×0.001, showing the weight of the least
significant decimal digit. To get an actual fractional number with specified precision,
multiply the register value by the given multiplier. To write a fractional number into
the register, divide the number by the given multiplier.
2.6.3 32-bit Modulo-10000 Format
Energy counters 287-294 and 301-302 are read in two contiguous 16-bit registers in a
modulo-10000 format. The first (low order) register contains the value mod 10000,
and the second (high order) register contains the value/10000. To get the true energy
reading, the high order register value should be multiplied by 10,000 and added to the
low order register.
2.7 User Assignable Registers
The EM720 has 120 user assignable registers in the address range of 0 to 119, any of
which you can map to any register address accessible in the instrument. Registers that
reside in different locations may be accessed by a single request by re-mapping them
to adjacent addresses in the user assignable registers area.
The actual addresses of the assignable registers, which are accessed via addresses 0
through 119, are specified in the register map (registers 120 through 239), where
register 120 contains the actual address of the register accessed via register 0,
register 121 contains the actual address of the register accessed via register 1, and so
on. The assignable registers and the map registers themselves may not be re-mapped.
To build your own register map, write to map registers 120 to 239 the actual
addresses you want to read from or write to via the assignable area (registers 0 to
119). 32-bit long registers should always be aligned at even addresses.For example, if
you want to read registers 7136 (1-second V1 voltage, scaled short integer) and
14720-14721 (kWh Import, long integer) via registers 0-2, do the following:
- write 14720 to register 120
- write 14721 to register 121
- write 7136 to register 122
Reading from registers 0-2 will return the kWh reading in registers 0 (low 16 bits) and
1 (high 16 bits), and the voltage reading in register 2.

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2.8 Password Protection
The EM720 has a password protection for setups, cumulative registers and log files
from being changed or cleared via communications. Refer to the EM720 Operation
Manual for details.
A user password must be written into the 32-bit device authorization register (44378-
44379) before another write request is issued. If the correct password is not supplied,
the meter will respond to all write requests directed to the meter setup and reset
registers with the exception code 01 (illegal operation). It is recommended to clear the
authorization register after you have completed your changes in order to activate
password protection.
2.9 Data Recording and File Transfers
2.9.1 Log File Organization
Historical files are stored to the non-volatile flash memory. Memory is allocated for
each file statically when you set up your files and will not change unless you re-
organize the files. The EM720 automatically performs de-fragmentation of the memory
each time you re-organize your files. This prevents possible leakage of memory caused
by fragmentation.
Data records in a file are arranged in the order of their recording. Each record has a
unique 16-bit sequence number that is incremented modulo 65536 with each new
record. The sequence number can be used to point to a particular record in the file, or
to check the sequence of records when uploading files from the device.
Each file has a write position pointer that indicates the place where the next record will
be recorded, and a read position pointer that indicates the place from where the
current record will be read. Both pointers show sequence numbers of the records they
point to rather than record offsets in the file.
After acknowledging a record you have read, the read pointer automatically advances
to the next record in the file. When the read pointer gets to the record to which the file
write pointer points, the end-of-file (EOF) flag is set. It is automatically cleared when a
new record is added to the file, or when you explicitly move the read pointer to any
record within a file.
If a file has a wrap-around attribute (circular file), the most recent records can
overwrite the oldest records. When this happens at the current read position, the read
pointer automatically advances forward in order to point to the oldest record in the file.
The EM720 keeps a separate read pointer for each communication port so that access
to the same file through a different port will not affect current active sessions for other
ports.
Multi-section Files
Log files can have one or more (up to 20) sections for multi-channel recording. An
ordinal file consists of a single section. Some files, such as daily profile log files and
waveform log files, are arranged as multi-section files.
A multi-section file is subdivided into multiple sections of the same structure, one
section per recording channel. The number of sections in each file is defined at the
time you set up your files and may not change unless you re-organize the file. Each
section within a multi-section file can be addressed by a section number, or by a
section channel ID.
A multi-section file has a single write position pointer for all sections and stores data in
all sections simultaneously. This means that records with the same sequence number
in all sections are associated with the same event. A multi-section file has also a single
read position pointer for all sections.
Data Log Files
Conventional data log files can store up to 16 measured parameters per a record. Any
data measured by the device can be stored in the log file. The number of parameters

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that each record will hold and the list of parameters you want to be recorded in the file
can be selected through the Data log setup registers for a particular file.
Recording data to data log files can be triggered through the setpoints, either on a
time basis, or upon any event detected by the setpoints.
Billing/TOU Profile Data Log Files
Data log files #15 and #16 are factory configured for monthly and daily profile logs of
the energy usage and maximum demand registers. A profile log file is organized as a
multi-section file that has a separate section for each energy and maximum demand
register. See Sections 3.15-3.16 for more information on the file record structure. A
file record stores the summary data (total of all tariffs) and all tariff data for each
configured Billing/TOU register.
The number of sections is taken automatically from your Billing/TOU Registers setup.
Since each Billing/TOU energy register has a shadow maximum demand register, the
number of sections in the file can be twice the number of the allocated Billing/TOU
registers.
Power Quality Statistics Log Files
Data log files #9 and #10 are configured to store the power quality statistics data on a
daily or weekly basis. They are organized as multi-section files. See Sections 3.11-3.14
for more information on the file record structure. You can review the list of parameters
recorded to the files through the file info request/response blocks using info requests
with variation 2 (see Section 3.10).
Waveform Log Files
Waveform log files are organized as multi-section files that store data for each
recording channel in a separate section. A waveform log file can record up to six AC
channels simultaneously: three voltage and three current waveforms. The number of
sections in a file, or channels that a file can store, is defined when you set up the file.
The channels that a file will record are selected in the waveform log setup. All selected
channels are recorded in successive file sections.
A waveform file has a single read pointer for all sections, so that data from all channels
of a single record can be read together without repositioning the file pointer. When you
point to a particular file record, data from all sections related to the same event are all
available for a read. Moreover, the EM720 takes all channel data for the currently
accessed record to a separate buffer, so that even when the record is overwritten at
the time of reading, you are still prevented from receiving partially updated data.
A single waveform record for a channel can contain up to 512 points of the sampled
input signal. Refer to the line frequency field in the channel header record to correctly
set up the time scale for the waveforms.
If a waveform log is configured to record more samples per event than a single record
can hold, the waveform recorder will store as many records per event as required to
record the entire event. All waveform records related to the event are merged in a
series and have the same series number, so that they can be plotted together. Each
record within a series has a unique serial number that allows tracking the sequence of
records in a series. A single waveform series can hold up to 81,920 points (2,560
cycles at a rate of 32 samples per cycle) of a sampled AC signal.
2.9.2 File Transfers
File transfer protocol provides both data transfer and information services. File transfer
is performed through two blocks of registers: a 32-word master request block and a
288-word read-only file response block. After a master application has written the
request into the file request block, the requested data is available for a read through
the file response block registers. File transfer functions allow changing the file or
section position in order to point to the desired record.
The information services use separate 8-word file info request and 200-word file info
response blocks. The extended file information is available including current file
pointers’ positions, file contents, the number of records in the file, allocated file size,
time of the last file update, and more.

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Common File Transfer
Log files can be read either in a sequence record-by-record, or in a random order. Each
Read-File request fills the file response block with the data of the record pointed to by
the file (or section) read pointer. If you want to begin reading a file from a particular
record, which sequence number is known, you can change the pointer position by
issuing the Set-File-Position request with the desired sequence number. If you want to
read a file from the beginning, send the Reset-File-Position request that moves the
pointer to the oldest file record. If you do not change the file position, then you will
continue reading the file from the record following the one you have read the last time
you accessed the file.
You need not explicitly move the file position to the following record if you want to
continue reading a file in sequence after you have uploaded the current record.
Instead, issue an acknowledgment request that automatically advances the file pointer
to the next record, and then read the record data through the file response block.
The file response block can contain more than one record. The number of records
available in the block and the file record size in words are always reported in the block
heading. There are no special rules on how to read records from the file transfer block.
You can read a single record or all records together, or begin reading from the last
record and end with the first record. However, you should remember: 1) after an
acknowledgment, the file position moves to the record following the last one you have
accessed in the file transfer block; and 2) data in the file transfer block does not
change until you either issue an acknowledgment, or explicitly change the file position
by the Set-File-Position or Reset-File-Position requests.
The file transfer is completed after you have read the last record of the file. Before
storing a file record to your database, always check bit 9 in the record status word,
which contains the end-of-file (EOF) flag. This bit set to 1 indicates that the file read
pointer does not point to any record within the file, and you should not store any
record that has this bit set. The EOF flag is set only after you have acknowledged the
last record of the file, so that testing for end-of-file requires one extra read. If you
wish to stop the transfer just after storing the last file record, acknowledge the record
and check bit 0 in the record status word. Bit 0 is set to 1 only once when you read the
last record of the file.
The following gives a summary of steps you should do to read an ordinal log file:
1. If you want to begin reading a file from a particular record or from the first record,
use either the Set-File-Position request with the desired record sequence number,
or the Reset-File-Position request. Preset a section number and channel ID to zero.
2. Write the Read-File request with a section number and channel ID set to zero.
3. Read the record data from the file response block.
4. Write an acknowledgment for the file. You need not fill all the request fields: only
the file function is required. The file pointer will be moved to the next file record.
5. Repeat steps 3-4 until all the file records are read.
Reading Multi-section Data Log Files
In a multi-section data log file, all user requests including an acknowledgment, the
Read-File, Set-File-Position and Reset-File-Position requests, relate to a particular file
section rather than to the file itself. The only request that affects the entire file is the
Erase-File that clears all the file sections together.
A file section can be requested either by a section number, or by a section channel ID.
If you use a channel ID, preset the section number field to 0xFFFF. If a section number
is specified, the channel ID field will not be checked. The device returns both fields in
the response block heading, so you can always identify what channel data is being
read from the present file section. If you want to know which channels are recorded to
the file sections, check the file channel mask in the file info block. This is a bitmap that
contains one in a bit position if a channel with an ID equal to the bit number is
recorded to the file, and contains zero if it is not.
The following gives a summary of steps for reading a multi-section data log file:

17
1. If you wish to begin reading a file section from a particular record or from the first
record, use either the Set-File-Position request with the desired record sequence
number, or the Reset-File-Position request. Specify either a section number, or the
channel ID for the section from where you want to read data. If you use a channel
ID, preset the section number field to 0xFFFF.
2. Write the Read-File request with the section number and channel ID as shown in
the previous step.
3. Read the record data from the file response block.
4. Write an acknowledgment for the file. The file section pointer will be moved to the
next record.
5. Repeat steps 3-4 until all the section records are read.
Reading Multi-section Waveform Files
Waveform files can be read as conventional multi-section files in the order described
above. Another way is to take advantage of the fact that waveform files have a single
read pointer for all file sections, so you can read records of all the channels related to
the same event at once without repositioning the file pointer. The following gives a
summary of steps for reading waveform files:
1. If you want to begin reading a file from a particular record or from the first record,
use either the Set-File-Position request with the desired record sequence number,
or the Reset-File-Position request. Preset the section field to zero.
2. Write the Read-File request. Address you request to the first file section (its
number is always zero), or to the first file channel (if you know channel’s ID). If
you use a channel ID, preset the section number field to 0xFFFF.
3. Read the channel’s data from the file response block. Store the received record’s
sequence number.
4. Write the Read-File request for the next file section or channel using the stored
record sequence number. The file response block will be refilled with the data for
the requested channel that is related to the record with the same sequence
number.
5. Repeat steps 3, 4 until all the channel records with the current sequence number
are read.
6. Write an acknowledgment. The file pointer will be moved to the next record.
Repeat steps 2-6 until all the file records are read.
Reading Real-time Waveforms
Real-time waveforms are accessed through the same transfer blocks just like the
waveform log files by addressing file 128. Writing the Read-File request for file 128
provides a simultaneous capture of 6 real-time waveform records – three voltage and
three current waveforms – into a communication buffer that can be read through the
common file response block. The following gives a summary of steps for reading real-
time waveforms:
1. Write the Read-File request for file 128. Address you request to the first file section
(its number is always zero), or to the first file channel (if you know channel’s ID).
If you use a channel ID, preset the section number field to 0xFFFF.
2. Read the channel’s data from the file response block.
3. Write the Read-File request for the next file section or channel. The file response
block will be refilled with the data for the requested channel.
4. Repeat steps 3, 4 until all the channel records are read.
5. Write an acknowledgment to release the buffer.

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2.10 TCP Notification Client
The TCP notification client can establish connections with a remote Modbus/TCP server
and send notification messages either on events, or periodically on a time basis.
Notification messages are sent via a block of 24 Modbus registers using write function
16. The following table shows the message exchange structure.
Modbus
Register Offset Description Type Comment
+0-1 Device serial number UINT32
+2-4 Device MAC address CHAR6
+5 Device address UINT16 1 for Ethernet,
COM2 port address for GPRS
+6-7 Device IP address UINT32 Network byte order
+8 Event type UINT16 See F22 in Section 5
+9 Event sequence number UINT16
+10-11 Start event timestamp, seconds UINT32 Local time since Jan 1, 1970
+12-13 Start event timestamp, seconds fraction, in
microseconds UINT32
+14-15 End event timestamp, seconds UINT32 Local time since Jan 1, 1970
+16-17 End event timestamp, seconds fraction, in
microseconds UINT32
+18 Not used UINT16 Written as 0
+19 Critical trigger ID UINT16 See Table below
+20-21 Critical trigger value UINT32 See Table below
+22-23 Reserved UINT32 Written as 0
The reported trigger type and value depend on the event source and are described in
the following table.
Event Source Trigger Type Trigger Value
Setpoint events Critical setpoint trigger caused setpoint
operation or release (see F12 in Section 5) Trigger entering or return value
PQ events PQ event trigger. For polyphase events, the
worst phase is reported (see Generic Data in
Section 3.4)
Maximum fault magnitude on the
reported phase
Fault events Current phase with highest recorded fault
current (see Generic Data in Section 3.4) Maximum fault current magnitude on the reported phase
After receiving a write acknowledgement from a server, a TCP connection is still open
for 10 seconds (20 seconds via GPRS) to give the server an opportunity to access
meter registers through an open socket. It may help you access the meter from
outside your local network when the server is located on another network, or when
using wireless GPRS communications. The notification client will respond to all server
requests as if it were a regular incoming connection.
In case a client connection is not used for following data transfers, it is recommended
for the server to close the connection immediately after sending a write
acknowledgement; otherwise there will be a 10-second delay before the
next notification may be sent.
If there is no activity on the connection socket, it will be closed in 10 seconds. In the
event a connection attempt was unsuccessful, the notification client retries two more
times before announcing a connection failure.
The server’s IP address, port number and starting Modbus register address are
programmable in the meter. To configure and enable the notification client in your
meter via PAS, select Communication Setup in the Meter Setup menu, and click on the
TCP Notification Client Setup tab. See “Setting-up TCP Notification Client” in the meter
manual for more information on the client setup.

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Client connections are triggered via programmable setpoints. To send event
notifications to a server, configure a setpoint to respond to desired triggers or to
periodic time events and add the "Send notification" action to the end of the setpoint
actions list.
Setpoint operation events triggered by regular analog and digital triggers are
reported twice - when the event starts and when it ends, except of the pulsed events
and time triggers that will be reported once. In the start notification message, the
event end timestamp is zeroed, and the critical trigger value indicates its entering
value, while the second notification message gives both the event start and end time
and shows the trigger return value.
In case of triggering notifications with events generated by the PQ and Fault recorders,
like the PQ EVENT, FAULT EVENT, EXTERNAL TRIGGER or FAULT DETECTED triggers,
the recorded power quality or/and corresponding fault events are reported instead of
setpoint-triggered notifications. Notification messages contain the fault event start and
end time, a critical phase and the maximum fault magnitude on the reported phase. If
regular triggers are added to the setpoint triggers list, then the setpoint operation
events will also be reported.

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3 Modbus Register Map
3.1 Modbus Setup Registers
Address Point ID Description Options/Range Units Type R/W Notes
Modbus Assignable Registers
0-119
+0 Register 0 contents 0-65535 UINT16 R/W
+1 Register 1 contents 0-65535 UINT16 R/W
...
+119 Register 119 contents 0-65535 UINT16 R/W
Assignable Registers Map
120-239
+0 Mapped register 0 address 0-65535 UINT16 R/W
+1 Mapped register 1 address 0-65535 UINT16 R/W
+119 Mapped register 119 address 0-65535 UINT16 R/W
Modbus Conversion Scales
240 Low raw scale 0 UINT16 R
241 High raw scale 9999 UINT16 R
Device Data Scales
242 Voltage scale, in secondary volts 60-600 (default 144V) 1V UINT16 R/W
243 Current scale, in secondary amps 10-500 (default is CT secondary
current ×Current Overload) ×0.1A UINT16 R/W