ROOTECH Accura 2300S/2350 Communication User Guide

Type
Communication User Guide
Enables True Enterprise-wide Energy Management
Distribution Panel Digital Power Meter
Accura 2300 Front
Accura 2300 Rear
Accura 2300-RS485 Rear
Accura 2300S Front
Three-phase Power Measuring Module
Single-phase Power Measuring Module
Accura 2350-3P-250A-105
TM-3P-105
Accura 2350-1P-250A-105
TM-1P-105
Accura 2350-3P-125A-90
TM-3P-90
Accura 2350-1P-125A-60
TM-1P-60
Accura 2350-3P-100A-75
TM-3P-75L
Accura 2350-1P-100A-50
TM-1P-50L
Accura 2350-3P-60A-75
TM-3P-75
Accura 2350-1P-60A-50
TM-1P-50
Accura 2350-3P-CT5A-75
Accura 2350-1P-50A-35
Accura 2350-1P-30A-35
Accura 2350-1PSH-50A-35
Accura 2350-1PSH-30A-35
Split-core Three-phase
Power Measuring Module
Split-core Single-phase
Power Measuring Module
Split-core Single-phase Single-hole
Power Measuring Module
Accura 2350-3PSC-250A-105
Accura 2350-1PSC-250A-105
Accura 2350-1PSCSH-800A
Accura 2350-3PSC-125A-90
Accura 2350-1PSC-125A-60
Accura 2350-1PSCSH-630A
Accura 2350-3PSC-60A-75
Accura 2350-1PSC-60A-50
Accura 2350-1PSCSH-400A
Accura 2350-3PSC-CT5A-90
Split-core Single-phase Three-feeder
Power Measuring Module
Special-purpose Module
Accura 2350-1P3FSC-125A
(Basic Module)
Accura 2350-GAS
Accura 2350-GW
Accura 2350-1P3FSC-125A-DIZCT
(Option Module)
Accura 2350-TEMP
Accura TSEN
Accura 2350-TEMPS
Accura 2350-1P3FSC-60A
(Basic Module)
Accura 2350-DO
Accura 2350-IDC
Accura 2350-VDC
Accura 2350-1P3FSC-60A-DIZCT
(Option Module)
Accura 2350-DCM-50V-
80A
Accura 2350-DCM-500V-
80A
Accura 2300[S]/2350 Communication Manual
Notice
2013 Rootech Inc. All Rights Reserved
Page 5
Notice
Symbols
Caution
Indicates the presence of dangerous voltage which can cause severe injury or death if
proper precautions are not followed.
Caution
Alerts users of the presence of hazards which can cause injury to persons, property
damage or damage to the device if proper precautions are not followed.
Note
Indicates major instructions for the installation, operation, and maintenance of the
product.
Indicates alternative voltage or current.
Indicates direct voltage or current.
Installation Considerations
The installation, operation, and maintenance of the product should be performed only by qualified,
competent personnel that have received appropriate training for high voltage and current devices.
Caution
If hazardous voltages are mishandled while installing and operating the product in the field, it can
cause serious injury or death.
This device must be installed and serviced only by qualified personnel who have in-depth knowledge
of installing, commissioning and operating the device and have had appropriate training. He or she
should have read and understood the various safety measures and warnings stated in the instructions.
Before carrying out any work on the device, switch off the power supply to the device.
Always use an appropriate voltage detection device to confirm the absence of voltage.
Always power the device with the correct rated voltage.
Install the device in a suitable electrical cabinet by following recommended installation instructions.
Failure to take these precautions could cause serious injuries or death.
Notice
Accura 2300[S]/2350 Communication Manual
Page 6
2013 Rootech Inc. All Rights Reserved
Caution
Observe the following instructions, or it may cause permanent damage to the product.
To ensure that the device operates correctly, make sure that:
The device is correctly installed.
The auxiliary power supply voltage indicated on the product is observed: AC 85 265 V, DC 100
300 V
About the Manual
Rootech Inc. reserves the right to make changes in the product specifications shown in this User Guide
without prior notice. We recommend that customers should obtain the latest information on product
specifications and the manual before making orders.
In the absence of written agreements, Rootech, Inc. assumes no liability for applications assistance,
customer’s system design, or infringement of patents or copyrights induced by third parties arising from
the use of the products described herein.
We endeavor to provide accurate information in the document. However, we are not responsible for any
errors which may appear here and reserves the right to make changes without prior notice.
Limitation of Liability
Where applicable law allows and does not prohibit or restrict such limitation, Rootech, Inc’s liability for
this product shall be limited to the amount actually paid by customers for the product.
Accura 2300[S]/2350 Communication Manual
Warranty
2013 Rootech Inc. All Rights Reserved
Page 7
Warranty
Rootech Inc. provides warrants for two years from the product receipt date only to the original purchaser
of the products and software that are sold or licensed by the company.
To obtain warranty service, the purchased products should be free from serious defects in material and
workmanship.
The software is provided in an up-to-date version, thus we do not offer any warranty for the software
product.
In order to make a product claim under the warranties described above, the original purchaser should
immediately contact Rootech headquarters. Upon receiving claims, Rootech will check out the product
either at where the purchaser is or at the company after receiving the product from the customer, who is
responsible for the cost of shipping the product. After inspecting the product, we will provide repair or
replacement services for the product.
Rootech will decide at its discretion whether to repair or replace it or give a refund for the product for
when the warranty period for the product expired or issues related to the product are not applicable for
warranty terms and conditions.
Limitation of Warranty
The Warranty does not apply to uninterrupted or error-free operation of the product or cover normal
wear and tear of the product or costs caused by the removal, installation, or troubleshooting of the
customer's electrical systems.
Defects caused by any of the following factors are not covered under the warranty.
Improper use (alteration, accident, misuse, abuse) or failure to act in accordance with installation,
operation or maintenance instructions
Unauthorized modifications, changes or repair attempts
Failure to comply with applicable safety standards & regulations
Damages coming from when transporting or storing the product
Damages caused by the force majeure event, including fire, flood, earthquakes, storm damage,
overvoltage & lightning
If the original identification marks (trade-mark, serial number, etc.) have been defaced, altered, or
removed.
Warranty
Accura 2300[S]/2350 Communication Manual
Page 8
2013 Rootech Inc. All Rights Reserved
Rootech shall not be liable for any other claims except the claims made by customers, including the
original purchaser, his employees, agents, or contractors for any loss, damage, or expense incurred related
to the purchased product when the above warranty terms and conditions are not fulfilled.
Any technical assistance with system design provided by Rootech's personnel or representatives shall be
deemed to be a suggestion. The original purchaser is responsible for determining the feasibility of such
suggestions and should conduct tests to prove their feasibility.
It is the original purchasers responsibility to determine the suitability of the product and associated
documentation. The original purchaser should acknowledge that 100% up time is not realizable because
of possible hardware or software defects. The original purchaser should recognize that such defects and
failures may cause inaccuracies or malfunctions.
No agency, corporate entity, or employee of Rootech or other companies has authority to amend, modify
or extend the terms and conditions of this warranty in any way without express written authorization from
Rootech, Inc.
Standard Compliance
Process Control Equipment
E324900
MSIP-REM-RTE-ACCURA2300
MSIP-REM-RTE-ACCURA2300S
Accura 2300[S]/2350 Communication Manual
Revision History
2013 Rootech Inc. All Rights Reserved
Page 9
Revision History
The following versions of Accura 2300[S]/2350 Communication User Guide have been released.
Revision
Date
Description
Revision 1.40
May 13, 2015
Separated Accura 2300 Communication Manual from Accura
2300S Communication Manual
Changed the symbol used to indicate a range from ~ (tilde) to -
(hyphen)
Updated the standard logo image
Revision 1.41
July 20, 2015
Updated content on the standard compliance section
Revision 1.50
February 19, 2016
Added data on Accura 2350-1P3FSC module
Revision 1.51
October 24, 2016
Added the bookmark feature
Revision 1.60
October 4, 2018
Integrated Accura 2300/2300S Communication Manuals
Changed the terms zero voltage/current to residual
voltage/current
Revision 1.70
January 29, 2019
Added data on Accura 2350-DCM module
Revision 1.71
May 31, 2019
Added detailed description of DO pulse generation related to
energy
Revision 1.72
October 28, 2019
Changed the term DSP to MCU, extended the range of harmonic
orders, and added contents on the DCM module’s voltage
polarity and energy
Revision 1.90
August 22, 2022
Added data on Accura 2350-TEMP module
Added the setting of demand sync mode
Modified the description of the hardware revision
Contents
Accura 2300[S]/2350 Communication Manual
Page 10
2013 Rootech Inc. All Rights Reserved
Contents
Chapter 1
Modbus Protocol of Accura 2300[S] ........................................................................................................... 14
Modbus Protocol Overview ....................................................................................................................................... 14
Modbus Protocol ........................................................................................................................................................................................ 14
Modbus RTU Protocol .............................................................................................................................................................................. 14
Modbus TCP Protocol ............................................................................................................................................................................... 14
Modbus Packet Structure ........................................................................................................................................... 15
Modbus RTU Packet Structure ............................................................................................................................................................. 15
Modbus TCP Packet Structure .............................................................................................................................................................. 16
Accura 2300[S] Modbus Supports ............................................................................................................................ 17
Unit ID (Modbus TCP only) .................................................................................................................................................................... 17
Function Code .............................................................................................................................................................................................. 17
Multiple Access Policy .............................................................................................................................................................................. 18
Connection Termination Policy ............................................................................................................................................................ 18
Accura 2300[S] Function Code Packet Structure ................................................................................................... 19
Function 3 [03h]: Read Holding Registers ...................................................................................................................................... 19
Function 6 [06h]: Write Single Register ........................................................................................................................................... 21
Function 16 [10h]: Write Multiple Registers .................................................................................................................................. 22
Function 101 [65h]: Read Multi-block Registers ......................................................................................................................... 24
Chapter 2
Modbus Map of Accura 2300[S] .................................................................................................................. 27
Modbus Map Overview .............................................................................................................................................. 27
Summary Map .............................................................................................................................................................................................. 28
Data Format ................................................................................................................................................................................................... 30
Data Attribute of Register Access ...................................................................................................................................................... 31
System Information Category ................................................................................................................................... 34
Accura 2300[S] System Information .................................................................................................................................................. 34
Accura 2350 System Information ........................................................................................................................................................ 35
Accura TSEN System Information ....................................................................................................................................................... 37
Setup Category ............................................................................................................................................................ 38
Remote Setup Unlock ............................................................................................................................................................................... 38
General Setup ............................................................................................................................................................................................... 38
Network Setup ............................................................................................................................................................................................. 39
Network Time Protocol(NTP) Setup .................................................................................................................................................. 40
Measurement Setup .................................................................................................................................................................................. 41
User Interface Setup .................................................................................................................................................................................. 44
DI/DO Setup of Accura 2300[S] ........................................................................................................................................................... 45
Dip/Swell Setup ........................................................................................................................................................................................... 47
ID Setup of Accura 2350 ......................................................................................................................................................................... 48
Management Setup of Accura 2350 ................................................................................................................................................. 50
General Setup of Accura 2350 ............................................................................................................................................................. 51
Extended Setup of Accura 2350 .......................................................................................................................................................... 59
Accura 2300[S]/2350 Communication Manual
Contents
2013 Rootech Inc. All Rights Reserved
Page 11
Energy Level Setup of Accura 2350 ................................................................................................................................................... 73
Aggregation Setup ..................................................................................................................................................................................... 75
Group Setup of Accura 2350-1P ......................................................................................................................................................... 76
Phase Open Event Setup ......................................................................................................................................................................... 76
Fuse Fail Event Setup ................................................................................................................................................................................ 77
Modbus Serial Communication Setup .............................................................................................................................................. 77
Over Current Event Setup ....................................................................................................................................................................... 78
Over Demand Current Event Setup ................................................................................................................................................... 78
Over Temperature Event Setup ........................................................................................................................................................... 79
Over Leakage Current Event Setup .................................................................................................................................................... 79
Summer Time Setup .................................................................................................................................................................................. 80
Power Event Setup ..................................................................................................................................................................................... 81
User-defined Event Setup ....................................................................................................................................................................... 82
LED Blink Setup ............................................................................................................................................................................................ 83
User-defined Expression Setup ............................................................................................................................................................ 84
Control Category ......................................................................................................................................................... 86
Remote Control Unlock ........................................................................................................................................................................... 86
Measurement Control ............................................................................................................................................................................... 86
User Interface Control of Accura 2350............................................................................................................................................. 87
Digital Input / Digital Output Control of Accura 2300[S] ....................................................................................................... 87
Extended Control of Accura 2350 ...................................................................................................................................................... 88
Measurement Data Category .................................................................................................................................... 92
Measurement Overview ........................................................................................................................................................................... 92
Voltage Data of Accura 2300[S] .......................................................................................................................................................... 97
Data of Accura 2350.................................................................................................................................................................................. 98
Max/Min Voltage Values and Timestamp of Accura 2300[S] ............................................................................................. 118
Max/Min Values and Timestamp of Accura 2350 .................................................................................................................... 120
Harmonics Data ......................................................................................................................................................................................... 140
Waveform Data .......................................................................................................................................................................................... 142
TEMP Trend Data ...................................................................................................................................................................................... 143
Measurement Event Data Category ....................................................................................................................... 144
Measurement Event Data ..................................................................................................................................................................... 144
Measurement Event Data Detailed .................................................................................................................................................. 146
Measurement Event Clear ..................................................................................................................................................................... 160
Chapter 3
Modbus Map Application ............................................................................................................................ 161
Register Addressing ................................................................................................................................................................................. 161
Data Format ................................................................................................................................................................................................. 161
Endian ............................................................................................................................................................................................................. 161
Data Collection Check: Address Error and Endian Error ....................................................................................................... 162
Device Setup ............................................................................................................................................................... 163
Remote Setup Unlocking ...................................................................................................................................................................... 163
Remote Setup Locking ........................................................................................................................................................................... 163
Device Control ............................................................................................................................................................ 164
Contents
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2013 Rootech Inc. All Rights Reserved
Remote Control Unlocking ................................................................................................................................................................... 164
Remote Control Locking ....................................................................................................................................................................... 164
Collection of Measurement Data ............................................................................................................................ 165
Flowchart ....................................................................................................................................................................................................... 165
Selection of Aggregation ...................................................................................................................................................................... 167
Selection of Buffer Index ....................................................................................................................................................................... 168
Fetch of Measurement Data ................................................................................................................................................................ 168
Validity Check and Collection of Voltage Data ......................................................................................................................... 168
Validity Type Check and Collection of Module Data .............................................................................................................. 169
Appendix A
Sample of Modbus RTU Packet .............................................................................................................. 170
Request Packet ........................................................................................................................................................................................... 170
Response Packet........................................................................................................................................................................................ 170
Appendix B
Sample of Modbus TCP Packet ............................................................................................................... 171
Request Packet ........................................................................................................................................................................................... 171
Response Packet........................................................................................................................................................................................ 171
Appendix C
CRC-16(Modbus) Algorithm .................................................................................................................... 172
CRC Table ..................................................................................................................................................................................................... 172
CRC Function............................................................................................................................................................................................... 172
Appendix D
Writing User-defined Expressions .......................................................................................................... 173
Expression Component .......................................................................................................................................................................... 173
Format of Module Data ......................................................................................................................................................................... 173
Format of Number Data ........................................................................................................................................................................ 174
Format of Normal Operator ................................................................................................................................................................ 174
Format of Casting Operator ................................................................................................................................................................ 175
Format of End-of-stream ...................................................................................................................................................................... 175
User-defined Expression Example ..................................................................................................................................................... 175
Accura 2300[S]/2350 Communication Manual
Figures
2013 Rootech Inc. All Rights Reserved
Page 13
Figures
Fig 1.1 Private holding register for each connection ............................................................................................................... 18
Fig 2.1 Read access of holding register .......................................................................................................................................... 31
Fig 2.2 Write access of holding register .......................................................................................................................................... 31
Fig 2.3 Private Read access of holding register: Read Access ............................................................................................. 32
Fig 2.4 Private Read access of holding register: Read Parameter ...................................................................................... 32
Fig 2.5 Private Write access of holding register: Write Parameter .................................................................................... 33
Fig 2.6 Private Write access of holding register: Write Access ............................................................................................ 33
Fig 2.7 Aggregation of measured data ............................................................................................................................................ 92
Fig 3.1 Flowchart of measurement data collection .................................................................................................................. 166
Chapter 1
Modbus Protocol of Accura 2300[S]
Accura 2300[S]/2350 Communication Manual
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2013 Rootech Inc. All Rights Reserved
Chapter 1
Modbus Protocol of Accura 2300[S]
Modbus Protocol Overview
In this section, we will introduce the fundamentals of the Modbus RTU protocol and the Modbus TCP
protocol that are used in Accura 2300[S] for more details on the definition of Modbus protocol, Modbus
RTU protocol and Modbus TCP protocol, see www.modbus.org.
Modbus Protocol
The Modbus protocol is the application protocol that defines the rules for organizing and interpreting
data that are independent of the data transmission means. Modbus protocol uses port number 502. The
Modbus protocol establishes the format for master’s request by placing into it a slave device (or
broadcast) address, a function code defining the requested action, any data to be sent, and an error-
checking field. The slave’s response message is also constructed using Modbus protocol. It contains fields
confirming the action taken, any data to be returned, and an error-checking field. If an error occurred
when receiving a message, or if the slave is unable to perform the requested action, the slave will
construct an error message and send it as its response.
Modbus RTU Protocol
The Modbus RTU protocol is a version of Modbus protocol that is designed to work under a serial
communication environment such as RS-485, RS-232, etc. This protocol uses the pre-set device address
to identify each device and CRC to check the errors. It does not allow multiple accesses through serial
communications.
Modbus TCP Protocol
The Modbus TCP (also Modbus TCP/IP) is similar to the Modbus RTU protocol, but enhanced to work
more effectively under TCP/IP network layer. The primary function of TCP is to ensure that all packets of
data are received correctly, while IP makes sure that messages are correctly addressed and routed.
The TCP/IP combination is merely a transport protocol, and does not define what the data means or how
the data is to be interpreted (this is the job of the application protocol, the Modbus protocol in this case).
The Modbus TCP/IP combines a physical network (Ethernet), with a networking standard (TCP/IP) to carry
the data of the Modbus message structure between compatible devices. The Modbus TCP embeds a
standard Modbus data frame into a TCP frame, without the Modbus checksum.
The requests and the responses may not be matching in order. Also, it is not required to maintain the
gaps between packets. In addition, since the protocol is based on TCP, multiple accesses are possible.
The maximum number of multiple accesses supported may differ depending on the individual devices.
Accura 2300[S]/2350 Communication Manual
Chapter 1
Modbus Protocol of Accura 2300[S]
2013 Rootech Inc. All Rights Reserved
Page 15
Modbus Packet Structure
Modbus RTU Packet Structure
The request and response packets of Modbus RTU are composed of the following fields.
Device Address
Function Code
Data
CRC
1 bytes
1 byte
n bytes
2 bytes
The meaning of each field is as follows.
Fields
Description
Device Address
Device address field is used to identify each slave device and can have any value within
the range of 1 to 247.
Function Code
When a request is sent from master to slave device, this function code field tells the slave
device what kind of action to perform.
In the case of normal response, the function code of the corresponding request is used
without alteration. In the case of error response, 80h is added to the request function
code.
Data
The data fields differ depending on the function code.
CRC
This is an error-checking field that is based on a Cyclical Redundancy Check (CRC) method.
The CRC field checks the contents of the entire message. It is generated using CRC-16
(Modbus) algorithm. For more details, see Appendix C
Chapter 1
Modbus Protocol of Accura 2300[S]
Accura 2300[S]/2350 Communication Manual
Page 16
2013 Rootech Inc. All Rights Reserved
Modbus TCP Packet Structure
The request and response packets of Modbus TCP are composed of the following fields.
Modbus TCP Header
Function Code
Data
Transaction ID
Protocol ID
Length
Unit ID
2 bytes
2 bytes
2 bytes
1 byte
1 byte
n bytes
The meaning of each field is as follows.
Fields
Description
Transaction ID
This identification field is used for transaction pairing when multiple messages are sent along the
same TCP connection by client without waiting for a prior response. The requests and the
responses may not be matching in order.
Normally, this value is increased by 1 at each request and supposed to circulate within the range
of 0000h - FFFFh. At the response, the transaction ID assigned to the corresponding request is
copied without alteration.
Protocol ID
This field is always 0 for Modbus services and other values are reserved for future extensions. The
same applies to the request and the response.
Length
This field is a byte count of the remaining fields and includes the Unit ID byte, function code
byte, and the data fields.
Unit ID 1
This field is used to identify a remote server located through the serial communication under the
device that supports TCP/IP network.
Function Code
When a request is sent from client to slave device, this function code field tells the slave device
what kind of action to perform.
In normal response, the function code of the corresponding request is used without alteration. In
error response, 80h is added to the request function code.
Data
The data fields differ depending on the function code.
1. In Accura 2300[S], this value should always be fixed to 1. Accura 2300[S] has all the measurement data
of Accura 2350 that are connected to Accura 2300[S] through the internal communication between them.
Accura 2300[S]/2350 Communication Manual
Chapter 1
Modbus Protocol of Accura 2300[S]
2013 Rootech Inc. All Rights Reserved
Page 17
Accura 2300[S] Modbus Supports
Unit ID (Modbus TCP only)
In Accura 2300[S], this value should always be fixed to 1. Accura 2300[S] has all the measurement data of
Accura 2350 that are connected to Accura 2300[S] through the internal communication between them.
Function Code
Accura 2300[S] supports the following function codes.
Function code
Decimal
[Hexadecimal]
Name
Description
3 [03h]
Read Holding Registers 1
Reads the contents of holding registers 1- 65536 in the slave
device.
The request message specifies the starting register and the
quantity of registers to be read. Registers are addressed starting
at zero: registers 1 - 16 are addressed as 0 - 15.
6 [06h]
Write Single Register
Writes a value to a single holding register, one of 1 - 65536 in the
slave device.
The request message specifies the holding register reference to
be written. Registers are addressed starting at zero: register 1 is
addressed as 0. The requested preset value is specified in the
request data field.
16 [10h]
Write Multiple Registers
Writes values to multiple consecutive holding registers 1 - 65536
in the slave device.
The request message specifies the starting holding register to be
written. Registers are addressed starting at zero: register 1 is
addressed as 0. The requested preset values are specified in the
request data field.
101 [65h]
Read
Multi-block Registers
This function code is a user-defined function code.
It is a single Read Packet that can read one or several holding
register blocks. Each holding register block is a group of
consecutive registers.
This function code has the effect of reducing the communication
overhead because it can read data of the registers distributed in
wide valid range at once. This function code is provided only in
the Modbus TCP protocol. Details are described in the packet
structure.
1. Holding register is 16-bit (2-byte) word.
Chapter 1
Modbus Protocol of Accura 2300[S]
Accura 2300[S]/2350 Communication Manual
Page 18
2013 Rootech Inc. All Rights Reserved
Multiple Access Policy
Accura 2300[S] supports up to 16 (TCP 15, RTU 1) simultaneous connections.
Each connection is independent from others. Each connection is capable of performing a private task
using separate private holding registers for its own. The holding register of which the access attribute is
marked as PR (private read) or PRW (private read / write) in the Modbus Map has a separate private
holding register allocated for each connection. Therefore, even if a connection changes the value of the
private register of itself, the private register values of other connections are not changed.
Fig 1.1 Private holding register for each connection
Master A
device
working
parameters
Modbus connection 1 PRW private holding registers
Accura 2300[S]
private holding registers
private holding registers
Master B
Modbus connection 2 PRW
Modbus connection 3 PRW
Same register numbers
application & fetch
application & fetch
application & fetch
Connection Termination Policy
Accura 2300[S] terminates the connection of Modbus TCP protocol in the following cases.
A request for connection termination or forced termination is received.
No request was received for 1 minute (up to App Ver. 1.77) or 10 minutes (from App 1.78)
The received protocol ID value is not zero.
The received function code is not supported.
Accura 2300[S]/2350 Communication Manual
Chapter 1
Modbus Protocol of Accura 2300[S]
2013 Rootech Inc. All Rights Reserved
Page 19
Accura 2300[S] Function Code Packet Structure
The detailed packet structure of each function code provided by Accura 2300[S] is as follows.
Function 3 [03h]: Read Holding Registers
This function code can read some parts of the holding registers 1 - 65536 in the slave device.
Each holding register is 2-byte word.
Request
Function Code
Starting Address
Quantity of Registers
1 byte
2 bytes
2 bytes
Response
Function Code
Byte Count
Register Values
1 byte
1 byte
2 * (Quantity of Registers) bytes
Error Response
Error Code
Exception Code
1 byte
1 byte
Detailed Structure of Request
Name
Byte Length
Description
Function Code
1
3 [03h]: Read holding registers
Starting Address
2
Starting address to be read
Registers are addressed starting at zero: Register address is obtained by
subtracting by 1 from register number of Modbus Map.
Holding registers 1 - 65536 are addressed as 0 - 65535.
Quantity of
Registers
2
Number of registers to be read
Standard range: 1 - 125
Allowed range by Accura 2300[S]: 1 - 250
Accura 2300[S] is designed to be read up to 250 registers. However, when
reading 128 or more registers, measures to cope with the errors should be
considered, as the Byte Count field of the Response packet can
experience an overflow.
Chapter 1
Modbus Protocol of Accura 2300[S]
Accura 2300[S]/2350 Communication Manual
Page 20
2013 Rootech Inc. All Rights Reserved
Detailed Structure of Response
Name
Byte Length
Description
Function Code
1
3 [03h]: Read holding registers
Byte Count
1
2 * (Quantity of Registers), Since it has 1-byte space, an overflow might
occur if the quantity of registers is 128 or more.
Register Values
2 * Quantity
of Registers
Contents of holding registers to be read
Contents of holding registers are described in the Modbus Map.
Detailed Structure of Error Response
Name
Byte Length
Description
Error Code
1
131 [83h]: Error response of Read Holding Registers
Exception Code
1
2: When the holding register number to be read exceeds the limitation of
65536
3: When the requested Quantity of Registers is 0 or above 250.
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ROOTECH Accura 2300S/2350 Communication User Guide

Type
Communication User Guide

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