Yokogawa VJ User Manual

User’s Manual

VJ Series Communication Functions

IM 77J01J11-01E

3rd Edition

Blank Page

Introduction

This instruction manual describes the communication functions of the VJ Series signal conditioners and contains information on how to create communication programs.

Read the manual carefully to understand the communication functions of the VJ Series.

The VJ Series signal conditioners have the following communication protocols.

● PC link communication protocol

● MODBUS communication protocol

● Ladder communication protocol

Note that the VJ Series signal conditioner cannot communicate with a higher-level device with a communication protocol other than these.

You are required to have background knowledge of the communication specifications of higher-level devices, their communication hardware, language used for creating communication programs, and so on.

■ Intended Readers

This manual is intended for people familiar with the functions of the VJ Series signal conditioners, control engineers and personnel in charge of maintaining instrumentation and control equipment.

■ Related Documents

The following instruction manuals all relate to the communication functions of the VJ series signal conditioners. Read them as necessary.

● A variety of instruction manuals for VJ Series signal conditioners describing mounting, wiring, and how to calibrate the signal conditioners.

IM 77J01J11-01E 3rd Edition : Oct. 15, 2007-00

Documentation Conventions

■ Symbols

This manual uses the following symbols.

● Symbols Used in the Main Text

CAUTION

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.

Notices

■ Regarding This Instruction 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.

iii

■ 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 precautions 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

CAUTION This symbol on the product indicates that the operator must refer to an explanation in

the instruction 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.

Functional Grounding Terminal This symbol indicates that the terminal must be connected to ground prior to operating

the equipment.

IM 77J01J11-01E 3rd Edition : Oct. 15, 2007-00

■ 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.

IM 77J01J11-01E 3rd Edition : Oct. 15, 2007-00

VJ Series Communication Functions

CONTENTS

Introduction........................................................................................................... i

Documentation Conventions ...............................................................................ii

Notices .................................................................................................................iii

1. Setup ....................................................................................................... 1-1

1.1 Setup Procedure ............................................................................................. 1-1

1.2 Notes on Setting Parameters ......................................................................... 1-2

2. Communication Specifications.............................................................. 2-1

2.1 RS-485 Communication Specifications ......................................................... 2-1

Toc-1

IM 77J01J11-01E 3rd Edition

3. PC Link Communication ........................................................................ 3-1

3.1 Overview.......................................................................................................... 3-1

3.1.1 Configuration of Command ............................................................... 3-2

3.1.2 Configuration of Response ............................................................... 3-3

3.1.3 Response Error Codes ..................................................................... 3-4

3.2 Commands ...................................................................................................... 3-5

3.2.1 List of Commands ............................................................................. 3-5

3.2.2 BRD Reading I Relays on a Bit-by-bit Basis ..................................... 3-6

3.2.3 BRR Reading I Relays on a Bit-by-bit Basis in a Random Order....... 3-7

3.2.4 BRS Specifying I Relays to be Monitored on a Bit-by-bit Basis ......... 3-8

3.2.5 BRM Monitoring I Relays on a Bit-by-bit Basis ................................. 3-9

3.2.6 WRD Reading D Registers/I Relays on a Word-by-word Basis....... 3-10

3.2.7 WRR Reading D Registers/I Relays on a Word-by-word Basis in a Random

Order ...............................................................................................3-11

3.2.8 WRS Specifying D Registers/I Relays to be Monitored on a Word-by-word

Basis .............................................................................................. 3-12

3.2.9 WRM Monitoring D Registers/I Relays on a Word-by-word Basis ... 3-13

3.2.10 INF Reading the Model, Presence/Absence of Options, and Revision3-14

3.3 Communication with Higher-level Devices ................................................. 3-15

3.3.1 Example of Communication Program Created Using Visual Basic .. 3-16

3.3.2 Communication with UT Link Module .............................................. 3-20

3.3.3 Communication with Graphic Panel ................................................ 3-21

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

4. Ladder Communication.......................................................................... 4-1

5. MODBUS Communication...................................................................... 5-1

6. Functions and Usage of D Registers ..................................................... 6-1

Toc-2

4.1 Overview.......................................................................................................... 4-1

4.2 Commands/Responses at the PLC ................................................................ 4-2

4.2.1 Command/Response Component Elements ..................................... 4-2

4.2.2 Reading Parameters......................................................................... 4-3

4.2.3 Response Error Codes ..................................................................... 4-4

5.1 Overview.......................................................................................................... 5-1

5.1.1 Configuration of Message ................................................................. 5-2

5.1.2 Specifying D Registers...................................................................... 5-3

5.2 Function Codes ............................................................................................... 5-4

5.2.1 List of Function Codes ...................................................................... 5-4

5.2.2 Response Error Code[Response] ..................................................... 5-8

5.3 Example of Setting up Commercially Available SCADA Software ............... 5-9

6.1 Overview of D Registers ................................................................................. 6-1

6.2 Interpretation of D Register Map Table .......................................................... 6-1

6.3 D Register Map Table ...................................................................................... 6-2

6.3.1 Contents of D Registers .................................................................... 6-3

7. Functions and Usage of I Relays ........................................................... 7-1

7.1 Status............................................................................................................... 7-2

Appendix Table of ASCII Codes (Alphanumeric Codes) ............................App.-1

Revision Information ............................................................................................ i

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

1. Setup

This chapter describes the setup procedure required to use the communication functions (PC link, Ladder, and MODBUS) and the communication parameters of the VJ Series.

1.1 Setup Procedure

Set up the communication functions on the VJ Series as follows:

Set up the communication function parameters of the VJ Series. (See section 1.2.)

Connect a higher-level device and a VJ Series. (See the connection diagram below.)

Create communication programs for the higher-level device to perform communication.

010101E.EPS

Note: Refer to the documentation of each higher-level device when creating communication programs.

1-1

• Connection

Terminating resistor

220 Ω 1/4 W

Shielded

Grounding resistance of less than 100 Ω

PC or PLC

B (+)

A (-)

RS-232C

(straight cable)

PLC

(RS-232C/RS-485 converter)

ML2

B (+)

A (-)

VJ Series VJ Series

B (+)

A (-)

Grounding resistance of less than 100 Ω

VJ Series VJ Series

B (+)

A (-)

3rd Edition : Oct. 15, 2007-00

B (+)

A (-)

COMCOM

B (+)

A (-)

COMCOM

Terminating resistor

220 Ω 1/4 W

Grounding resistance of less than 100 Ω

IM 77J01J11-01E

010102E.EPS

3rd Edition : Oct. 15, 2007-00

1.2 Notes on Setting Parameters

This section describes the setting parameters for using the communication functions and their setting ranges.

CAUTION

The details of VJ Series communication functions need to be the same as those of the communication functions of the higher-level device to be connected. Check the communication parameters of the higher-level device first, then set up those of the VJ Series using the Handy Terminal or setting tool (VJ77).

Table 1-1 Parameters to be Set for Communication Functions

1-2

Parameter Name

Protocol selection Without sum check

Address Communication rate Parity Stop bit Data length

*1: When "Ladder" is selected in protocol selection, it is fixed to "8."

When "ASCII mode" is selected for MODBUS communication, it is fixed to "7." When "RTU mode" is selected, it is fixed to "8."

Symbol

PROTOCOL

ADDRESS

BAUD RATE

PARITY

STOP BIT

DATA LEN

Setting Range

PC link communication

With sum check

MODBUS communication ASCII mode

RTU mode

LadderLadder communication

1 to 99

1200, 2400, 4800, and 9600

NONE, EVEN, ODD

1, 2

7, 8 (*1)

PC link communication

without sum check

● Protocol selection (PROTOCOL)

Set the communication protocol identical to that of the higher-level device to be connected.

Default

9600

EVEN

010201E.EPS

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

● Address number (ADDRESS)

Set the address number of the VJ Series itself. An address number of 1 to 99 may be assigned in any order. However, there is a limitation - the number of VJ Series to be connected to a single communication port is limited to 31.

Example of connecting four VJ Series signal conditioners to a higher-level device by setting address numbers of 1, 50, 10, and 20

1-3

ADDRESS=1 ADDRESS=20ADDRESS=10ADDRESS=50

Maximum overall cable length of 1200 m for a maximum of 31 substations

010202E.EPS

● Communication rate (BAUD RATE)

Set the communication rate identical to that of the higher-level device to be connected. (Otherwise, proper communication cannot be achieved.) The unit of the communication rate is bps (bits per second).

● Parity (PARITY)

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.

● Stop bit (STOP BIT)

Set the stop bit identical to that of the higher-level device to be connected.

● Data length (DATA LEN)

Set the data length identical to that of the higher-level device to be connected. (When Ladder or MODBUS communication is chosen in protocol selection, the data length is fixed.)

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

Blank Page

2. Communication Specifications

The RS-485 communication interface has the PC link communication, Ladder communication, and MODBUS communication protocols.

Table 2-1 VJ Series Communication Specifications

2-1

Communication Hardware Terminal

Communication Protocol Specifications

Maximum Communication Rate

2-wire RS-485 communication system Terminal numbers: 2, 5, 6

PC link communication without sum check PC link communication with sum check MODBUS communication (ASCII mode) MODBUS communication (RTU mode) Ladder communication

9600 bps

020001E.EPS

Table 2-2 Types of Devices to be Connected

Devices to be Connected

PC PC, graphic panels, and PLCs

(FA-M3’s UT link modules)

PLCs (sequencers) and FA-M3 ladder communication module

Communication Protocol

MODBUS communication PC link communication

Ladder communication

Example of Connected Devices

General-purpose PC General-purpose PC, FA-M3,

and GP Series

General-purpose PLCs (sequencers)

2.1 RS-485 Communication Specifications

020002E.EPS

Table 2-3 RS-485 Communication Interface

Item

Standard EIA, RS-485, Compatible Maximum number of devices to be connected 31 Communication system Synchronization Asynchronous (start-stop)

Maximum communication distance 1200 m Communication rate 1200, 2400, 4800, 9600

2-wire, half duplex

No protocolCommunication protocol

Specifications

020101E.EPS

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

Blank Page

3. PC Link Communication

3.1 Overview

The use of PC link communication enables the VJ Series to communicate with a device such as a PC, graphic panel, or FA-M3's UT link module. Such a device can be used in communication to read data from D registers or I relays, both of which are internal registers of the VJ Series signal conditioners.

Maximum overall cable length of 1200 m for a maximum of 31 substations

3-1

030101E.EPS

Figure 3-1 Connection of Substations in PC Link Communication

Hereafter, PCs are generally called "higher-level devices."

3.1.1 Configuration of Command

Commands sent from a higher-level device to VJ Series signal conditioners, consist of the following elements.

3-2

Number of Bytes 12 2 1 3 211

Element STX Address

number

(ADDRESS)

(1) (2) (3) (4) (5) (7) (8) (9)(6)

CPU

number

Time to wait

for response

Command Data

Variable length

Checksum ETX CR

corresponding

to command

030102E.EPS

(1) STX (Start of Text)

This control code indicates the start of a command. The ASCII code is 02 in hexadecimal.

(2) Address Number (01 to 99)

Address numbers are used by the higher-level device to identify VJ Series signal conditioners at the communication destination. (They are identification numbers specific to the VJ Series signal conditioners.)

(3) CPU number

This number is fixed to “01”.

(4) Time to Wait for Response

This is fixed to “0”.

(5) Command (See subsection 3.2.1, “List of Commands”)

Specify a command to be issued from the higher-level device.

(6) Data Corresponding to Command

Specify an internal register (D register or I relay), number of data pieces, and others.

(7) Checksum

This converts the ASCII codes of texts between the character next to STX and the character immediately before the checksum into hexadecimal values and adds them byte by byte. It then fetches the single lowermost byte of the added results as the checksum.

This column is required only for PC link communication with checksum. PC link communication without checksum does not require this 2-byte space of ASCII code.

(8) ETX (End of Text)

This control code indicates the end of a command string. The ASCII code is “03” in hexadecimal.

(9) CR (Carriage Return)

This control code indicates the end of a command. The ASCII code is “0D” in hexadecimal.

CAUTION

The control codes “STX”, “ETX”, and “CR” are essential for commands when you create a communication program for PC link communication. Omission of any of them or incorrect order of them results in communication failure.

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00

3.1.2 Configuration of Response

Responses from the VJ Series with respect to a command sent from the higher-level device consist of the elements shown below, which differ depending on the condition of communication; normal or failure.

1) Normal Communication

When communication completes normally, the VJ Series returns a character string "OK" and data corresponding to a command.

Number of Bytes Variable length12 22 211

Element STX Address

number

(ADDRESS)

CPU

number

2) In the Event of Failure

If communication does not complete normally, the VJ Series returns a character string "ER" and error code (EC1 and EC2). (See subsection 3.1.3, “Response Error Code”.)

• No response is made in case of an error in address number specification or CPU number specification.

• If a VJ Series cannot receive EXT in a command, response may not be made.

* As a countermeasure, provide a timeout process in the communication functions of the higher-level device or in

communication programs.

Number of Bytes 12 22223 211

Element STX ER EC1 EC2 Command Checksum ETX CRAddress

number

(ADDRESS)

CPU

number

OK Parameter data Checksum ETX CR

3-3

030105E.EPS

030106E.EPS

IM 77J01J11-01E

3rd Edition : Oct. 15, 2007-00