ROOTECH ACCURA 3500 Communication User Guide

Type
Communication User Guide
ACCURA 3500
High Accuracy Digital Power Meter
Added with Extension modules
Suits your various applications
Communication User Guide[English]
Rev 1.2
Page
2
Page 3
Notice
Limitation of Liability
Rootech Inc. reserves the right to make changes in the device specifications shown in this Users
Guide without notice. Rootech Inc. advises customers to obtain the latest specifications of device
before giving orders to confirm that the information being relied on by the customer is up to date.
In the absence of written agreement to the contrary, Rootech Inc. assumes no liability for Rootech
Inc. applications assistance, customers system design, or infringement of patents or copyrights of
third parties by or arsing from the use of devices described herein.
Except to the extent prohibited by applicable law, under no circumstances shall Rootech Inc. be
liable for consequential damages sustained in connection with said product and Rootech Inc.
neither assumes nor authorizes any representative or other person any obligation or liability other
than such as is expressly set forth herein.
2006 Rootech Inc.
The information contained in this document is believed to be accurate at the time of publication,
however, Rootech Inc. assumes no responsibility for any errors which may appear here and
reserves the right to make changes without notice.
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4
Standard Compliance
CE Approved
EN61326 and IEC61010
MEASURING EQUIPMENT
35DX
E258934
KSA 9001:2001/ ISO 9001:2001
QMS-1347
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Warranty Information
For products and software that are sold or licensed by Rootech Inc. during the period from the
date of receipt by you until the present, Rootech warrants only to the original purchaser
The purchased products other than software shall be substantially free from material defects in
material and workmanship by Rootech for two years from the date receipt by you.
The software itself is provided as is without any warranty of any kind.
Limitation of Warranty
These limited Warranties shall not apply to any product that has been subject to alteration,
accident, misuse, abuse, neglect or failure to exactly follow Power Measurement's instructions for
operation and maintenance.
In order for the original purchaser to make a claim under the warranties described above, the
original purchaser must promptly contact Rootech headquarter. After receiving such notice,
Rootech may either in Rootechs sole discretion, examine the product at the original purchasers
site or issue shipping instructions to the original purchaser to return the relevant product to
Rootech for examination at the original purchasers expense, transportation charges prepaid.
If after examining the product Rootech reasonably confirms that such examined product does not
meet the warranties, then the original purchasers sole remedy and Rootechs sole obligation or
liability shall be, at Rootechs option, to repair, replace or refund the price paid for that product.
Regardless of whether any remedy set forth herein fails of its essential purpose, except to the
extent the following limitation is prohibited by applicable law, Rootech shall not, in any event or
under any legal claim or theory, be liable to the original purchaser or any other person or entity
for special, indirect, incidental, punitive, liquidated, special or consequential damages whatsoever
with respect to any purchased product, including, without limitation, business interruption, loss of
use, profit or revenue, even if Rootech has been advised of the possibility of such damages. To the
extent that a limitation or exclusion of consequential damages are prohibited by applicable law,
then Rootechs liability shall be limited to twice the amount of the relevant purchased product.
Rootech shall not be liable for any claim- other than a claim solely for the breach of one of the
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above warranties that is made in accordance with the above described procedures- made by the
original purchaser, its employees, agents, or contractors for any loss, damage, or expense
incurred due to, caused by, or related to any purchased product
Any technical assistance provided by Rootech's personnel or representatives in system design shall
be deemed to be a proposal and not a recommendation. The responsibility for determining the
feasibility of such proposals rests with the original purchaser and should be tested by the original
purchaser.
It is the original purchaser’s responsibility to determine the suitability of any product and
associated documentation for its purposes. The original purchaser acknowledges that 100% "up"
time is not realizable because of possible hardware or software defects. The original purchaser
recognizes that such defects and failures may cause inaccuracies or malfunctions.
Only the terms expressed in these limited Warranties shall apply and no distributor, corporation or
other entity, individual or employee of Rootech or any other entity is authorized to amend, modify
or extend the Warranties in any way.
Copyright © 2006, Rootech Inc.
Headquarter
102-611, Digital Empire2, 486, Sin-dong, Yeongtong-gu,
Suwon, Korea
Tel : +82-31-695-7350 Fax : +82-31-695-7399
Homepage
www.rootech.com
E-mail
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Revision History
The following versions of the Accura 3500 Users Guide have been released.
Revision #
Revision date
Description
Firmware version
Revision 1.0 2006. 06. 30 Initial draft
Revision 1.1 2007. 04. 24 Adding Short-formed data block 1.18
Adding a register of extension module
configuration.
1.22
Revision 1.2 2007. 07. 13 Figure and comm examples modified
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Contents
Chapter 1 Serial Communication .............................................................................................. 11
Overview ............................................................................................................................... 11
Communication ..................................................................................................................... 12
Packet Recognition Time ................................................................................................. 13
Holding Time before transmitting Request Packet .......................................................... 13
Chapter 2 Communication Setup ............................................................................................ 14
Communication Wiring ......................................................................................................... 14
Setup ..................................................................................................................................... 15
Chapter 3 Modbus RTU Protocol ............................................................................................. 17
Packet Field of Modbus RTU ........................................................................................... 17
Exception Responses ...................................................................................................... 18
Broadcast Packets ........................................................................................................... 19
Packet Communications ........................................................................................................ 20
Function 03: Read Holding Registers .............................................................................. 20
Function 06: Write Single Register to Meter .................................................................... 21
Function 16: Write Multiple Registers to Meter ............................................................... 21
Reserved Registers ......................................................................................................... 22
Invalid Registers ............................................................................................................. 22
Chapter 4 Modbus RTU Map ................................................................................................... 23
Address Map Sections ........................................................................................................... 23
Overview ....................................................................................................................... 23
System information section ............................................................................................ 24
Configuration section ..................................................................................................... 24
Measurement section ..................................................................................................... 26
THD, k Factor section ..................................................................................................... 27
Demand, Maximum, Minimum section ........................................................................... 27
Harmonic section ........................................................................................................... 29
Vector diagram section ................................................................................................. 30
Waveform section .......................................................................................................... 31
Demand trend section .................................................................................................... 32
Reset section .................................................................................................................. 32
DIO module section ...................................................................................................... 33
DI module section ......................................................................................................... 33
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DO module section ....................................................................................................... 34
AI module section ......................................................................................................... 34
AO module section ....................................................................................................... 35
Short-formed data block Section .................................................................................... 36
Data Formats ........................................................................................................................ 40
Parameter Calculation ........................................................................................................... 42
Fixed sale ....................................................................................................................... 42
Variable scale ................................................................................................................ 42
APPENDIX A CRC-16 Calculation ............................................................................................ 44
CRC-16 Generation ............................................................................................................... 44
CRC Generation Procedure ............................................................................................ 44
CRC table ....................................................................................................................... 45
APPENDIX B Modbus RTU C Code Example ............................................................................. 46
Data Receiving and CRC Generation& Checking ................................................................... 46
Request Packet Generation ............................................................................................ 46
Response Packet Checking ............................................................................................. 46
Response Packet Checking ............................................................................................. 47
CRC functions................................................................................................................. 47
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Chapter 1 Serial Communication
Overview
Accura 3500 has a RS485 port on the rear side of meter for Master/Slave communication in the
field, and supports Modbus RTU protocol.
Modbus RTU protocol is a industry standard to efficiently transfer information of measuring and
control between master[PC or PLC] and slave[local devices, Accura 3300/3500/3550/7500].
Master/Slave Multi-drop
All communications on network conforms to a Master/Slave scheme.
Master will initiate and control all information on the communications loop.
Under no circumstances A Slave device initiate a communications sequence.
All communications occurs in the form of Packet, a packet being simply a serial string of 8-
bit bytes.
All Packets transmitted by the Master are requests. All Packets transmitted by a Slave are
responses.
At most one Slave can respond to a single request from a Master.
Modbus RTU Protocol
Industry standard protocol for general users.
Modbus RTU is recommended.
Designed according to Modicon Modbus RTU specifications.
Provides selective data communications by address map.
Most of automation programs provides the driver for Modbus RTU.
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Communication
The default serial communication setup of Accura 3500 is 8 data bits, even parity, 1 stop bit
The RS485 communications allows multiple devices to be connected on the same bus. Up to 32
devices can be connected on a single RS485 bus, which consists of a shielded twisted pair cable
more than AWG 22[0.33mm2]. The overall length of the RS485 cable connecting all devices
cannot exceed 1.2km[ or 4000ft].
Fig 1.1 RS485 Multi-drop Connection Diagram
Warning
The above T bridge branched off in the middle of communication line- can not guarantee the
communication reliability by voltage-drop on the line.
To connect an RS485 communication bus to a computer or other RS232 equipped device, a
RS232 to RS485 converter is required. The communication between computer and Accura 3500 is
to connect the Pins, Ta, Tb of the Accura 3500 to the RS485 two lines, Data+, Data-, and
between computer and converter is connected one to one. The timing flow Between request packet
and response packet is followed.
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Fig 1.2 RS485 Communication Timing
Packet Recognition Time
The data packet between master[PC] and slave[devices] has the following format. One packet
consists of consecutive data frames, and frames is recognized as the same packet for the
condition where the distance between frames is within 5ms. At least 10ms is required to
distinguish each packet.
Fig 1.3 Packet Structure
Holding Time before transmitting Request Packet
After receiving the data from meter, at least 10ms[particulary 13msec in 57600bps] is required to
send a next request packet.
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Chapter 2 Communication Setup
Communication Wiring
Fig 2.1 Communication Wiring
Pin name Ta[TRX+], Tb[TRX-]
Connector Screw terminal[Pluggable]
Wire 1.25 to 3.5 mm2[ 24 to 14 AWG], Shield twisted pair
Maximum Cable Length 1219m[4000ft]
Maximum Devices/bus 32
Note
UL2919 cable is recommended for communication.
Comm Indicator
Comm LED shows green when the meter is transmitting data.
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Setup
Each of these functions can be accomplished by pressing the Menu, Up, Down, and Enter buttons
on the front panel.
Display mode
View parameter measurements
Setup mode
Configure parameters[wiring, communication, and etc.]
Reset mode
Reset energy, demand, maximum, and minimum.
System mode
View meter system information[meter option, firmware version].
Module mode
View information of module added on rear side of the meter
Note
SETUP LED shows red when selecting Setup, Reset, System, and Module modes.
Setup Mode
In Setup mode, You can setup menus, such as PT/CT ratio, wiring, and communication after
mounting the meter.
Button Functions in Setup Mode
Button
Function
Enter setup mode by pressing the Up and Down buttons at the
same time.
Move to the previous menu screen.
Move to the next menu screen.
Enter setup edit mode to configure the displayed menu value.
the displayed value blinks
Exit setup mode and move to display mode.
Shows that the value of menu item is possible to be changed.
Button Functions in Setup Edit Mode
Button
Function
Increase the value of menu item.
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decrease the value of menu item.
Save the edited value of menu item, and the meter automatically
returns to Setup Mode.
When pressing at least two seconds, cursor is moved to higher position.
When pressing at least two seconds, cursor is moved to lower position.
Note
In setup edit mode, pressing button exits system edit mode and moves to display mode,
without saving the changed value of menu item.
Menu Items
Order
Menu Item
Range
Default
1
PT ratio 0.1 ~ 999.9 PT ratio = PT primary/ secondary 1.0
2
CT ratio 1 ~ 5000 CT ratio = CT primary/ secondary 10
3
Wiring mode
Single phase 2 wires
Single phase 3 wires
Three phase 3 wires, Open Delta
Three phase 4 wires
4
Comm address 1 ~ 247
5
Protocol Modbus RTU
Rootech
6
Speed[bps] 1200bps
2400bps
4800bps
9600bps
19200bps
38400bps
57600bps
7
Parity bits Even parity
Odd parity
None parity
8
Stop bits 1 ~ 2 1
Available only for manufacturer. In 57600bps, after receiving the data from meter, at least 13msecs is
required to send a next request packet. And when writing multiple registers to meter, the size of data word is
limited to 24 words.
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Chapter 3 Modbus RTU Protocol
Accura 3500 supports Modbus RTU.
Packet Field of Modbus RTU
Every modbus packet consists of four fields.
Slave Address Field
Function Field
Data Field
Error Check Field
Slave Address Field
The slave address field of a Modbus packet is one byte in length and uniquely identifies the slave
device involved in the transaction. Valid addresses range between 1 and 247. A slave device,
when receiving a request packet with the slave address field matching its own address, will
perform the command specified in the packet. A response packet generated by the slave will have
the same value in the slave address field.
Function Field
The function field of a Modbus resquest packet is one byte in length and tells the addressed slave
which function to perform. Similarly, the function field of a response packet tells the master what
function the addressed slave has just performed.
Function[Decimal]
Meaning
Description
03 Read Multiple register Obtains the current value from registers.
06 Write Single register Updates one single register to setup value
16 Write Multiple registers Updates more than a register to setup value
Data Field
The data field of a Modbus request is of variable length, and depends upon the function. This
field contains information required by the slave device to perform the command specified in a
request or data being passed back by the slave device in a response packet. Data in this field is
contained in 16-bit or 32-bit registers. Registers are transmitted in the order of high-order byte
first, low-order byte second. This ordering of bytes is called Big Endian format.
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Big Endian Example]]
High order byte = 3A hex
Low order byte = 12 hex
This register is transmitted in the order of 12AB
Error Check Field
The checksum field allows the receiving device to determine if a packet has been corrupted with
transmission errors. In Modbus RTU mode, 1 16-bit cyclic redundancy check[CRC-16] is used. The
sending device calculates a 16-bit value using the CRC-16 algorithm. The calculated value is
inserted in the error check field.
The receiving device performs the same calculation on the entire packet it receives, excepting the
error check field. If the calculated checksum is not equal to the checksum stored in the incoming
packet, transmission errors occurred and corrupted the packet. A bad packet will be ignored by
the receiving device. . See the Appendix A of this document for details of CRC-16 algorithm.
Packet Format
Slave address
Function
Data
Error check
1 byte 1 byte N 2 bytes 2 bytes
Exception Responses
If a Modbus master device sends an invalid command to Accura 3500 or attempts to read an
invalid holding register, an exception response will be generated. The high order bit of the
function code in an exception response is set to 1.
The data field of an exception response contains the exception error code.
Exception Response
Slave address
Function
Exception code
Error check
1 byte 1 byte 1 byte 2 bytes
Exception code
Name
Description
01 Illegal Function Unavailable command in Request Packet
02 Illegal Address Unavailable holding address in Request Packet
03 Illegal Value Unavailable data transfer in Holding Address
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Broadcast Packets
The purpose of a broadcast request packet is to allow all the slave devices to receive the same
command from the master. A broadcast request packet is the same as a normal request packet,
except the slave address field is set to zero.
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Packet Communications
this section illustrates the Modbus functions supported by the meter.
Function 03: Read Holding Registers
To read meter parameter values, a Master must send the slave device a Read Holding Registers
request packet. The Read Holding Registers request packet specifies a start register and a number
of registers to read.
Starting Address is a relative address according to register 40000[40001=0, 40002=1, 40101=
100, and etc.]. refer to Appendix B for CRC.
Request
Slave
Function
Starting address
Word count
Error check
03
1 byte 1 byte 2 bytes 2 bytes 2 bytes
Example]
A meter is configured as a Modbus slave device with slave address 1. A phase voltage has the
address 40101, and B phase voltage 40102. register 40101 is numbered as 100 when
transmitted.
slave address = 1, starting address = 64, word count = 2, crc high = 85, crc low = D4
Slave
Function
Starting Address
Word Count
Error Check
01 03 00 64 00 02 85 D4
Response
Slave
Function
Byte Count
Data Word 1
---
Data Word N
Error Check
03
---
1 byte 1 byte 1 byte 2 bytes
---
2 bytes 2 bytes
Data word represents the data required in the request packet. Byte count is two times word cout.
Example]
Slave device with address 1 has A phase voltage= 1A1B, B phase voltage= 223B.
slave address = 1, byte count = 4, crc high = D4, crc low = 5F
Slave
Function
Byte Count
Data Word 1
Data Word N
Error Check
01 03 04 1A 1B 22 3B D4 5F
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ROOTECH ACCURA 3500 Communication User Guide

Type
Communication User Guide

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