YOKOGAWA PR300 User manual

User’s
Manual
IM 77C01E01-10E
Model PR300
Power and Energy Meter
Communication Interface
(RS-485 and Ethernet Communications)
IM 77C01E01-10E
5th Edition

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IM 77C01E01-10E
Introduction
This user's manual describes the communication functions of the PR300 power and energy
meter and contains information on how to create communication programs.
Hereafter, the PR300 power and energy meter is simply referred to as the PR300.
Read the manual carefully to understand the communication functions of the PR300 .
The PR300 has the following communication protocols.
●PC link communication protocol
●Modbus /RTU and Modbus/ASCII communication protocols
●Modbus/TCP communication protocol (for the PR300 with Ethernet communication
function)
●PR201 original communication protocol
You are required to have background knowledge of the communication specifications of
higher-level devices, their communication hardware, language used for creating communi-
cation programs, and so on.
■Intended Readers
This manual is intended for people familiar with the functions of the PR300, control engi-
neers and personnel in charge of maintaining instrumentation and control equipment.
■Related Documents
The following user's manuals all relate to the communication functions of the PR300. Read
them as necessary.
●Model PR300 Power and Energy Meter User's Manual (electronic manual)
Document number: IM 77C01E01-01E
●Model PR300 Power and Energy Meter Startup Manual <Installation>
Document number: IM 77C01E01-02E
●Model PR300 Power and Energy Meter Startup Manual <Initial Setup Operations>
Document number: IM 77C01E01-03E
These manuals provide information about the procedure of installation, wiring and opera-
tion.
■Trademark
(1) All the brands or names of Yokogawa Electric's products used in this manual are
either trademarks or registerd trademarks of Yokogawa Electric Corporation.
(2) Ethernet is a registered trademark of XEROX Corporation in the United States.
(3) Company and product names that appear in this manual are trademarks or registered
trademarks of their respective holders.
Media No. IM 77C01E01-10E 3rd Edition : Feb. 15, 2007 (YK)
All Rights Reserved Copyright © 2006, Yokogawa Electric Corporation

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Documentation Conventions
■Symbols
This manual uses the following symbols.
●Symbols Used in the Main Text
NOTE
Draws attention to information that is essential for understanding the operation and/or
features of the product.
TIP
Gives additional information to complement the present topic.
See Also
Gives reference locations for further information on the topic.
●Symbols Used in Figures and Tables
[NOTE]
Draws attention to information that is essential for understanding the features of the
product.
[TIP]
Gives additional information to complement the present topic.
[See Also]
Gives reference locations for further information on the topic.
■Description of Displays
(1) Some of the representations of product displays shown in this manual may be exag-
gerated, simplified, or partially omitted for reasons of convenience when explaining
them.
(2) Figures and illustrations representing the PR300's displays may differ from the real
displays in regard to the position and/or indicated characters (upper-case or lower-
case, for example), the extent of difference does not impair a correct understanding of
the functions and the proper operations and monitoring of the system.

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IM 77C01E01-10E
Notices
■Regarding This User's Manual
(1) This manual should be passed on to the end user. Keep the manual in a safe place.
(2) Read this manual carefully to gain a thorough understanding of how to operate this
product before you start using it.
(3) This manual is intended to describe the functions of this product. Yokogawa Electric
Corporation (hereinafter simply referred to as Yokogawa) does not guarantee that
these functions are suited to the particular purpose of the user.
(4) Under absolutely no circumstance may the contents of this manual, in part or in whole,
be transcribed or copied without permission.
(5) The contents of this manual are subject to change without prior notice.
(6) Every effort has been made to ensure accuracy in the preparation of this manual.
Should any errors or omissions come to your attention however, please contact your
nearest Yokogawa representative or our sales office.
(7) The document concerning TCP/IP software has been created by Yokogawa based on
the BSD Networking Software, Release 1 that has been licensed from the University
of California.
■Regarding Protection, Safety, and Prohibition Against Unauthorized
Modification
(1) In order to protect the product and the system controlled by it against damage and
ensure its safe use, be certain to strictly adhere to all of the instructions and precau-
tions relating to safety contained in this document. Yokogawa does not guarantee
safety if products are not handled according to these instructions.
(2) The following safety symbols are used on the product and/or in this manual.
●Symbols Used on the Product and in This Manual
This symbol on the product indicates that the operator must refer to an explanation in
the user's manual in order to avoid the risk of injury or death of personnel or damage
to the instrument. The manual describes how the operator should exercise special
care to avoid electric shock or other dangers that may result in injury or loss of life.
Protective Grounding Terminal
This symbol indicates that the terminal must be connected to ground prior to operating
the equipment.

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IM 77C01E01-10E
■Force Majeure
(1) Yokogawa does not make any warranties regarding the product except those men-
tioned in the WARRANTY that is provided separately.
(2) Yokogawa assumes no liability to any party for any loss or damage, direct or indirect,
caused by the use or any unpredictable defect of the product.
(3) Be sure to use the spare parts approved by Yokogawa when replacing parts or
consumables.
(4) Modification of the product is strictly prohibited.
(5) Reverse engineering such as the disassembly or decompilation of software is strictly
prohibited.
(6) No portion of the software supplied by Yokogawa may be transferred, exchanged,
leased, or sublet for use by any third party without the prior permission of Yokogawa.

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CONTENTS
Model PR300 Power and Energy Meter
Communication Interface
(RS-485 and Ethernet Communications) IM 77C01E01-10E
Introduction........................................................................................................... i
Documentation Conventions ...............................................................................ii
Notices .................................................................................................................iii
1. Communications Overview
1.1 RS-485 Communication Specifications ......................................................... 1-1
1.2 Ethernet Communication Specifications....................................................... 1-1
2. Setup
2.1 Setup Procedure ............................................................................................. 2-1
2.1.1 Procedure for RS-485 Communication ............................................. 2-2
2.1.2 Procedure for Ethernet Communication ............................................ 2-3
2.1.3 Procedure for Ethernet-Serial Gateway Function .............................. 2-4
2.2 Setting Communication Conditions .............................................................. 2-6
2.2.1 Conditions for RS-485 Communication ............................................. 2-6
2.2.2 Conditions for Ethernet Communication ............................................ 2-8
2.2.3 Conditions for Ethernet-Serial Gateway Function ............................ 2-10
2.3 Wiring for Communication ........................................................................... 2-12
2.3.1 Wiring for RS-485 Communication .................................................. 2-12
2.3.2 Wiring for Ethernet Communication ................................................ 2-13
2.3.3 Wiring for RS-485 Communication for Ethernet-Serial Gateway Function .. 2-14
3. Procedures for Setting PR300 Functions
3.1 Basic Setting ................................................................................................... 3-2
3.1.1 Setting of VT Ratio ............................................................................ 3-2
3.1.2 Setting of CT Ratio............................................................................ 3-3
3.1.3 Setting of Integrated Low-cut Power ................................................. 3-4
3.2 Setting Pulse Output....................................................................................... 3-5
3.2.1 Selection of Measurement Item for Pulse Output .............................. 3-5
3.2.2 Pulse Unit ......................................................................................... 3-6
3.2.3 ON Pulse Width ................................................................................ 3-7
3.3 Setting Analog Output .................................................................................... 3-8
3.3.1 Selection of Measurement Item for Analog Output ............................ 3-8
3.3.2 Upper/Lower Limits of Scaling .......................................................... 3-9
3.4 Demand Setting ............................................................................................ 3-10
3.4.1 Demand Power/Current .................................................................. 3-10
3.4.2 Demand Period................................................................................3-11
3.4.3 Demand Alarm Mask Time .............................................................. 3-12
3.4.4 Demand Power Alarm Point ............................................................ 3-13

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3.4.5 Demand Current Alarm Point .......................................................... 3-14
3.4.6 Demand Alarm Release Function ................................................... 3-15
3.5 Communication Setting ................................................................................ 3-16
3.5.1 Protocol .......................................................................................... 3-16
3.5.2 Baud Rate ...................................................................................... 3-17
3.5.3 Parity .............................................................................................. 3-18
3.5.4 Stop Bit ........................................................................................... 3-19
3.5.5 Data Length .................................................................................... 3-20
3.5.6 Station Number............................................................................... 3-21
3.5.7 IP Address (for Ethernet communication) ........................................ 3-22
3.5.8 Subnet Mask (for Ethernet communication) .................................... 3-23
3.5.9 Default Gateway (for Ethernet communication) ............................... 3-24
3.5.10 Port Number (for Ethernet communication) ..................................... 3-25
3.6 Writing Energy Values .................................................................................. 3-26
3.6.1 Active Energy ................................................................................. 3-26
3.6.2 Regenerative Energy ...................................................................... 3-27
3.6.3 LEAD Reactive Energy ................................................................... 3-28
3.6.4 LAG Reactive Energy ..................................................................... 3-29
3.6.5 Apparent Energy............................................................................. 3-30
3.7 Executing Reset Operations ........................................................................ 3-31
3.7.1 Remote Reset ................................................................................ 3-31
3.7.2 Maximum/Minimum Values Reset ................................................... 3-32
3.7.3 Energy Value All-Reset ................................................................... 3-32
3.7.4 Active Energy Reset ....................................................................... 3-33
3.7.5 Regenerative Energy Reset ............................................................ 3-33
3.7.6 Reactive Energy Reset ................................................................... 3-34
3.7.7 Apparent Energy Reset .................................................................. 3-34
3.8 Setting Control States .................................................................................. 3-35
3.8.1 Integration Start/Stop ..................................................................... 3-35
3.8.2 Optional Integration Start/Stop ........................................................ 3-36
3.8.3 Demand Measurement Start/Stop................................................... 3-37
3.8.4 Confirmation and Release of Demand Alarm State ......................... 3-38
4. PC Link Communication Protocol
4.1 Overview.......................................................................................................... 4-1
4.1.1 Configuration of Command ............................................................... 4-2
4.1.2 Configuration of Response ............................................................... 4-3
4.1.3 Response Error Codes ..................................................................... 4-4
4.1.4 Specifying Broadcast ........................................................................ 4-5
4.2 Command and Response ............................................................................... 4-6
WRD Reads D registers on a word-by-word basis ................................... 4-7
WWR Writes data into D registers on a word-by-word basis..................... 4-8
WRR Reads D registers on a word-by-word basis in random order......... 4-9
WRW Writes data into D registers on a word-by-word basis in random order ... 4-10
WRS Specifies the D registers to be monitored on a word-by-word basis ........ 4-11
WRM Monitors the D registers on a word-by-word basis ........................ 4-12
INF6 Reads the model, suffix codes, and version information............... 4-13
INF7 Reads the maximum value of CPU ............................................... 4-14
4.3 Communication with Higher-level Devices ................................................. 4-15
4.3.1 Communication with FA-M3 (UT Link Module) ................................ 4-15

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4.4 Sample Program ........................................................................................... 4-17
4.4.1 Example of BASIC Program for Send and Receive ......................... 4-17
5. Modbus/RTU and ASCII Communication Protocols
5.1 Overview.......................................................................................................... 5-1
5.1.1 Configuration of Message ................................................................. 5-3
5.1.2 Specifying D Registers...................................................................... 5-4
5.1.3 Checking Errors ................................................................................ 5-4
5.1.4 Configuration of Response ............................................................... 5-7
5.1.5 Specifying Broadcast ........................................................................ 5-9
5.2 Message and Response ............................................................................... 5-10
03 Reads data from multiple D registers ............................................ 5-11
06 Writes data into D register ............................................................. 5-12
08 Performs loop back test ................................................................. 5-13
16 Writes data into multiple D registers.............................................. 5-14
6. Modbus/TCP Communication Protocol
6.1 Overview.......................................................................................................... 6-1
6.2 TCP/IP Communication .................................................................................. 6-3
6.3 Network Frame Structure ............................................................................... 6-4
6.3.1 MBAP Header Structure ................................................................... 6-4
6.3.2 PDU Structure .................................................................................. 6-4
6.4 Communication with Higher-level Devices ................................................... 6-5
6.4.1 List of Function Codes ...................................................................... 6-5
6.4.2 Specifying D Registers...................................................................... 6-5
6.4.3 Request and Response .................................................................... 6-6
03 Reads data from multiple D registers .............................................. 6-6
06 Writes data into D register ............................................................... 6-7
08 Performs loop back test ................................................................... 6-8
16 Writes data into multiple D registers................................................ 6-9
6.4.4 Response Error Codes ....................................................................6-11
6.5 Sample Program ........................................................................................... 6-12
6.5.1 Example of BASIC Program for Send and Receive ......................... 6-12
7. Functions and Usage of D Registers
7.1 Overview of D Registers ................................................................................. 7-1
7.2 Configuration of D Registers.......................................................................... 7-1
7.3 Interpretation of D Register Map Table .......................................................... 7-1
7.4 D Register Map ................................................................................................ 7-2
8. PR201 Original Communication Protocol
8.1 Overview.......................................................................................................... 8-1
8.2 Communication Specifications ...................................................................... 8-1
8.3 Command/Response Format ......................................................................... 8-2
8.4 List of Commands........................................................................................... 8-3
8.5 Command Details............................................................................................ 8-5
Appendix Table of ASCII Codes (Alphanumeric Codes)
Revision Information

<Toc> <Ind> <1. Communications Overview > 1-1
IM 77C01E01-10E
1. Communications Overview
1.1 RS-485 Communication Specifications
Protocols available for RS-485 communication interfaces include the PC link com-
munication protocol and the Modbus communication protocol.
Table 1.1 RS-485 Communication Specifications
Communication Hardware
Item Details Connected Device
2-wire system RS-485
PR201 original communication Personal computer etc. with SCADA
software installed to support PR201
original communication protocol
Compliant Standard
Protocol Specification
EIA RS-485
PC Link Communication with
and without checksum
Modbus Communication
(ASCII and RTU modes)
A PC installed with a driver for PC link
communication and SCADA software,
PLC (FA-M3 UT link module), etc.
A PC installed with a Modbus driver
and SCADA software,
a Modbus-compatible PLC, etc.
2400 bps, 9600 bps, 19200 bps
1200 m
31
2-wire, half-duplex
Start-stop synchronization
Non-procedural
Shielded twisted pair cable
(AWG24-equivalent size)
Baud Rate
Maximum Communication Distance
Maximum Number of
Connectable Devices
Transmission Method
Synchronization
Communication Method
Communication Cable
1.2 Ethernet Communication Specifications
Protocols available for Ethernet communication interfaces include the Modbus/TCP
communication protocol.
Table 1.2 Ethernet Communication Specifications
Communication Hardware
Compliant Standard
Access Control
Protocol Specification
Baud Rate
Maximum Segment Length
Maximum Connecting
Configuration
Communication System
Data Format
Maximum Number of
Connections
Item Details
10BASE-T/100BASE-TX
Ethernet IEEE802.3
CSMA/CD
Modbus communication (Port No.: 502)
10 Mbps/100 Mbps
100 m *1
Cascade max. 4 levels (for 10BASE-T)
max. 2 levels (for 100BASE-TX) *2
TCP/IP
Binary
1
Connected Device
Ethernet-equipped PC etc.
*1: Distance between the hub and module.
*2: The number of hubs connectable in cascade configuration.

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IM 77C01E01-10E
2. Setup
This chapter describes how to set up the PR300, which is equipped with RS-485
communication as a standard feature.
When using an Ethernet-equipped model, either RS-485 or Ethernet can be selected
by parameter setting for communications.
For details of use of RS-485 communication, see subsection 2.1.1 “Procedure for
RS-485 Communication.”
For details of use of the Ethernet communication, see subsection 2.1.2 “Procedure
for Ethernet Communication.”
For details of use of the Ethernet-serial gateway function, see subsection 2.1.3
“Procedure for Ethernet-Serial Gateway Function.”
2.1 Setup Procedure
Set up the communication functions on the PR300 as follows:
WARNING
To avoid an electric shock, be sure to turn off the power supply source to the equipment
involved before you start wiring.
Note: Create communication programs referring to the user’s manual for communications of each higher-level device.
Higher-level devices : PCs, PLCs (sequencers), and others.

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2.1.1 Procedure for RS-485 Communication
Communication parameters setting for PR300
Set up the communication function using
the front panel keys.
Subsection 2.2.1 “Conditions for RS-485
Communication”
Higher-level device
Station number 01
(arbitrary) Station number 02 (arbitrary) Station number 10 (arbitrary) Station number 20 (arbitrary)
Maximum communication distance: 1200 m
Maximum number of slave stations to be connected: 31
(Example)
See
Connect a higher-level device with PR300
Subsection 2.3.1
“Wiring for RS-485 Communication”
See
Create communication programs for the
higher-level device to perform
communication
Chapter 3
“Procedures for Setting PR300 Functions”
For communication protocol, see
Chapter 4
“PC Link Communication Protocol”
Chapter 5
“
Modbus/RTU and ASCII Communication Protocols ”
Chapter 8
“PR201 Original Communication Protocol”
For data storage location, see
Chapter 7
“Functions and Usage of D Registers”
See
1
2
3

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IM 77C01E01-10E
2.1.2 Procedure for Ethernet Communication
Ethernet
LAN
connection
HUB
Station number 01 (fixed)
IP address [192.168.1.2]
(arbitrary)
Station number 01 (fixed)
IP address [192.168.1.3]
(arbitrary)
Station number 01 (fixed)
IP address [192.168.1.4]
(arbitrary)
Station number 01 (fixed)
IP address [192.168.1.5]
(arbitrary)
Maximum distance between hub and module: 100 m
Maximum number of hubs connectable in cascade configuration:
4 levels for 10BASE-T
2 levels for 100BASE-TX
1
2
3
Note: It is recommended to use the Ethernet network as a dedicated one for the
PR300.
Communication parameters setting for PR300
Set up the communication function using
the front panel keys.
Subsection 2.2.2 “Conditions for Ethernet
Communication”
Higher-level device
IP address [192.168.1.1]
(arbitrary)
(Example)
See
Connect a higher-level device with PR300
Subsection 2.3.2
“Wiring for Ethernet Communication”
See
Create communication programs for the
higher-level device to perform
communication
Chapter 3
“Procedures for Setting PR300 Functions”
For communication protocol, see
Chapter 6
“Modbus/TCP Communication Protocol”
For data storage location, see
Chapter 7
“Functions and Usage of D Registers”
See

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IM 77C01E01-10E
2.1.3 Procedure for Ethernet-Serial Gateway Function
Station number 01 (fixed)
IP address [192.168.1.2] (arbitrary)
Higher-level device
IP address [192.168.1.1] (arbitrary)
Ethernet
PR300
(with Ethernet
communication function)
RS-485
Station number 02
(arbitrary) Station number 03 (arbitrary) Station number 20
(arbitrary)
(Example)
1
2
3
4
Communication parameters setting for PR300
Set up the communication function using
the front panel keys.
Subsection 2.2.2
“Conditions for Ethernet Communication”
Subsection 2.2.3
“
Conditions for Ethernet-Serial Gateway Function ”
See
Connect a higher-level device with PR300
Subsection 2.3.2
“Wiring for Ethernet Communication”
See
Connect a lower-level device with PR300
Subsection 2.3.3
“Wiring for RS-485 Communication for
Ethernet-Serial Gateway Function”
See
Create communication programs for the
higher-level device to perform
communication
Chapter 3
“Procedures for Setting PR300 Functions”
For communication protocol, see
Chapter 6
“Modbus/TCP Communication Protocol”
For data storage location, see
Chapter 7
“Functions and Usage of D Registers”
See
Note: It is recommended to use the Ethernet network as a dedicated one for the PR300.

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IM 77C01E01-10E
● VJET Ethernet/RS-485 converter as an Ethernet-serial gateway function
IP address [192.168.1.2] (arbitrary)
Higher-level device
IP address [192.168.1.1] (arbitrary)
Ethernet
VJET*
Ethernet/RS-485 converter
RS-485
Station number 01(arbitrary) Station number 02(arbitrary)
Station number 20 (arbitrary)
(Example)
* The VJET is Yokogawa’s converter. For details of use of the VJET, refer to its user’s manual.
Note: It is recommended to use the Ethernet network as a dedicated one for the PR300.
The communication conditions of any slave PR300 must conform to those of the VJET at
a higher level.

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2.2 Setting Communication Conditions
This section describes the setting parameters for using the communication func-
tions, and the setting ranges. For details of setting method, refer to the PR300
Power and Energy Meter User’s Manual (electronic manual).
2.2.1 Conditions for RS-485 Communication
This subsection describes the setting parameters for using the RS-485 communication
function, and the setting ranges.
Table 2.1 Parameters to be Set for Communication Functions
Parameter Name
Protocol
(COMM)
(ST-NO)
(RS-485
communication)
(B-RT)
(PRI)
(STP)
(DLN)
PC link without checksum
2400 bps
9600 bps
19200 bps
1
2
7
8
(NONE)
(EVEN)
(ODD)
(PCLK1)
(PCLK2)
(M ASC)
(M RTU)
(M TCP)
(PR201)
Parameter Symbol Menu Setting Range
Initial
Value
Baud rate
Parity*3
Stop bit*3
Data length*2 *3
Station number
9600
NONE
1
8
01
PCLK2
PC link with checksum
Modbus/ASCII
Modbus/RTU
Modbus/TCP*1
PR201 original
01 to 99 (01 to 31 recommended)
None
Even
Odd
*1: Modbus/TCP can be selected for the PR300 with Ethernet communication function only.
*2: When Modbus /RTU is selected for the protocol, select 8 for the data length. If 7 is selected for the data length,
communication is not possible.
*3: When PR201 original is selected for the protocol, select NONE for the parity, 1 for the stop bit and 8 for the data length.

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IM 77C01E01-10E
●Protocol (COMM)
Set the communication protocol identical to that of the higher-level device to be connected.
●Station number (ST-NO)
Set the station number of the PR300 itself. A station number of 01 to 99 may be assigned
in any order. However, the maximum number of PR300 to be connected to a single com-
munication port is 31.
When connecting two or more PR300 to a single communication port, set a different station
number to each.
Example of connecting a higher-level device with four PR300 having station numbers 01,
05, 10, and 20
Higher-level device
Station number 01
(arbitrary) Station number 05 (arbitrary) Station number 10 (arbitrary) Station number 20 (arbitrary)
Maximum communication distance: 1200 m
Maximum number of slave sations to be connected: 31
(Example)
●Baud rate (B-RT)
Set the baud rate identical to that of the higher-level device to be connected. (Otherwise,
proper communication cannot be achieved.)
●Parity (PRI)
Set the handling of parity to be carried out when data is sent or received. Set the parity bit
state identical to that of the higher-level device to be connected.
* When PR201 original is selected for the protocol, select NONE for the parity.
●Stop bit (STP)
Set the stop bit identical to that of the higher-level device to be connected.
* When PR201 original is selected for the protocol, select 1 for the stop bit.
●Data length (DLN)
Set the same data length as for the upper device that is to be connected.
* When Modbus/RTU is selected for the protocol, select 8 for the data length.
* When PR201 original is selected for the protocol, select 8 for the data length.

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2.2.2 Conditions for Ethernet Communication
This subsection describes the setting parameters for using the Ethernet communication
function, and the setting ranges.
Table 2.2 Parameters to be Set for Communication Functions
(RS-485
Communication)
(Ethernet
Communication)
*
2
(IP-1)
IP address-1
IP address-2
IP address-3
IP address-4
192
0 to 255
(IP-2)
168
0 to 255
(IP-3)
1
0 to 255
(IP-4)
1
0 to 255
(PORT)
Port number 502
502, 1024 to 65535
(SM-1)
Subnet mask-1
Subnet mask-2
Subnet mask-3
Subnet mask-4
255
0 to 255
(SM-2)
255
0 to 255
(SM-3)
255
0 to 255
(SM-4)
0
0 to 255
(DG-1)
Default gateway-1
Default gateway-2
Default gateway-3
Default gateway-4
0
0 to 255
(DG-2)
0
0 to 255
(DG-3)
0
0 to 255
(DG-4)
0
0 to 255
(E-SW)
Ethernet setting switch
OFF, ON
(PCLK1)
(PCLK2)
(M ASC)
(M RTU)
(M TCP)
(PR201)
PCLK2
(COMM)
Parameter Name Parameter Symbol Menu Setting Range
Initial
Value
Protocol
PC link without checksum
PC link with checksum
Modbus/ASCII
Modbus/RTU
Modbus/TCP*
1
PR201 original
*1: Modbus/TCP can be selected for the PR300 with Ethernet communication function only.
*2: Ethernet communication menu is displayed when Modbus/TCP is selected for the protocol.

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IM 77C01E01-10E
●Protocol (COMM)
Set the protocol to Modbus/TCP.
●IP address-1 to 4 (IP-n) [n: integers from 1 to 4]
Set the IP address for the PR300 by the following format.
IP address IP-1
0 to 255
IP-2
0 to 255
IP-3
0 to 255
IP-4
0 to 255
●Subnet mask-1 to 4 (SM-n) [n: integers from 1 to 4]
Set the subnet mask for the PR300 by the following format.
Subnet Mask SM-1
0 to 255
SM-2
0 to 255
SM-3
0 to 255
SM-4
0 to 255
●Default gateway-1 to 4 (DG-n) [n: integers from 1 to 4]
Set the default gateway for the PR300 by the following format.
Default Gateway DG-1
0 to 255
DG-2
0 to 255
DG-3
0 to 255
DG-4
0 to 255
NOTE
Before performing setup of IP address, subnet mask, and default gateway, consult the
administrator for the network to which the PR300 is to be connected.
●Port number (PORT)
Set the port number for the PR300.
NOTE
To activate the settings of IP address, subnet mask, default gateway, and port number, set
the Ethernet setting switch to ‘ON’after setting them.
●Ethernet setting swtich (E-SW)
This switch activates the Ethernet communication parameters settings. Setting this param-
eter to ON activates the settings of IP address, subnet mask, default gateway, and port
number.
This parameter automatically reverts to OFF in about 20 seconds after being set to ON.

2-10
<Toc> <Ind> <2. Setup>
IM 77C01E01-10E
2.2.3 Conditions for Ethernet-Serial Gateway Function
The Ethernet-serial gateway function is a function that reads/writes data from/to other
devices equipped with RS-485 serial communication function using the Modbus/TCP
protocol via the PR300.
With this function, the higher-level device can access the devices connected to the RS-485
serial communication line in the same way as to access the devices connected to Ethernet.
Ethernet
10BASE-T, 100BASE-TX
Station number 01 (fixed)
Higher-level device
PR300
(with Ethernet
communication function)
RS-485
Station number 02
(arbitrary) Station number 03 (arbitrary) Station number 04 (arbitrary)
(Example)
Device with RS-485 serial
communication function
Power Monitor of POWERCERT series
Digital indicating controller of
GREEN series
Signal conditioner of JUXTA series
The PR300 operates as a gateway that changes the Modbus/TCP protocol received via
network to the Modbus/RTU protocol for the serial devices connected to the RS-485
communication interface. Therefore, the devices supporting the Modbus/RTU protocol are
required for the devices to be connected.
NOTE
•If the Ethernet-serial gateway function is used, set a station number other than 01 for
the RS-485 communication devices which are slaves of the PR300 connected to
Ethernet.
•If the Ethernet communication function is used, the RS-485 communication interface
is used specifically for the Ethernet-serial gateway function. Therefore, it is not pos-
sible for a higher-level device such as a PC to access the PR300 via the RS-485
communication interface.

<Toc> <Ind> <2. Setup> 2-11
IM 77C01E01-10E
●Setting for PR300 to perform the Ethernet-serial gateway function
To use the Ethernet-serial gateway function, set the parameters of subsection 2.2.2, “Con-
ditions for Ethernet Communication”and set a parity (PRI) in Table 2.3.
When the protocol is set to Modbus/TCP, the parameters of RS-485 other than the parity
are fixed and unchangeable.
Table 2.3 Parameters of PR300 to Perform the Ethernet-Serial Gateway Function
(ST-NO)
(RS-485
communication)
(B-RT)
(PRI)
(STP)
(DLN)
01 (fixed)
9600
NONE
1
8
1 (fixed)
8 (fixed)
01
9600 bps (fixed)
NONE
EVEN
ODD
Parameter Name Parameter Symbol Menu Setting Range
Initial
Value
Baud rate
Data length
Station number
None
Even
Odd
Parity
Stop bit
●Slave PR300
The station number of any slave PR300 (device for RS-485 communication) must be a
different number other than 01.
The communication conditions for any slave PR300 (device for RS-485 communication)
other than the station number must conform to those in Table 2.3.
Table 2.4 Parameters of Slave PR300
(ST-NO)
(RS-485
communication)
(B-RT)
(PRI)
(STP)
(DLN)
2400 bps
9600 bps
19200 bps
1
2
7
8
NONE
EVEN
ODD
02 to 99
9600
NONE
1
8
01
Parameter Name
Parameter Symbol Menu Setting Range
Initial
Value
Baud rate
Data length
Station number
None
Even
Odd
Parity
Stop bit
When using the VJET Ethernet/RS-485 converter as an Ethernet-serial gateway function,
the communication conditions of any slave PR300 must conform to those of the VJET at a
higher level. The initial value of the VJET parity is EVEN.