CG39FDI-3r2: MODBUS Slave FB Library - Siemens Modbus Slave FB Library contains the Modbus Slave (MODBUS_S) function block, which allows the control module to act as a Modbus slave

CG39FDI-3 CONTENTS

May 1997 i

TABLE OF CONTENTS

SECTION AND TITLE PAGE

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11.1 PRODUCT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21.2 SOFTWARE REGISTRATION AND SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.2.1 Software Registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-31.2.2 Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.3 RELATED LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

2.0 SOFTWARE INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12.1 DISK IDENTIFICATION AND BACKUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12.2 INSTALLATION PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

3.0 CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.1 PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.2 ACCESSING THE FUNCTION BLOCK LIBRARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.3 GENERAL CONCEPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.4 CONFIGURATION GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

4.0 FUNCTION BLOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14.1 MODBUS SLAVE FUNCTION BLOCK (MODBUS_S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4.1.1 Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24.1.2 Modbus Function Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-64.1.3 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-94.1.4 Soft List Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

4.2 SERIAL FUNCTION BLOCK (SERIAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-134.2.1 Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-134.2.2 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-134.2.3 Soft List Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

A.0 APPENDIX A SS APPLICATION EXAMPLE 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1A.1 HANDLING WRITES FROM THE MODBUS MASTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2

B.0 APPENDIX B SS APPLICATION EXAMPLE 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1B.1 HANDLING WRITES FROM THE MODBUS MASTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

C.0 APPENDIX C SS ERROR CODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 D.0 APPENDIX D SS SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

E.0 APPENDIX E SS CABLE CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

F.0 APPENDIX F SS ENTRELEC RS-232/RS-485 CONVERTER CONNECTIONS . . . . . . . . . . . . F-1

CONTENTS CG39FDI-3

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G.0 APPENDIX G SS REDUNDANT SYSTEM WIRING CONFIGURATION . . . . . . . . . . . . . . . . . G-1

TABLE OF CONTENTS(Continued)

SECTION AND TITLE PAGE

H.0 APPENDIX H SS USING MODBUS_S AS A SERIAL ANALYZER . . . . . . . . . . . . . . . . . . . . . . H-1H.1 SERIAL ANALYZER INPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-2H.2 SERIAL ANALYZER OUTPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-2H.3 SERIAL ANALYZER SOFT LIST PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-3

LIST OF FIGURES

FIGURE AND TITLE PAGE

A-1 MODBUS_S Configuration Showing On-line Data for Example 1 . . . . . . . . . . . . . . . . . . . . . . . . . A-1A-2 DATA Array Element Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2A-3 Register Writes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

B-1 MODBUS_S Configuration Showing On-line Data for Example 2 . . . . . . . . . . . . . . . . . . . . . . . . . . B-1B-2 DATA Array Element Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2B-3 Coil Writes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

E-1 Minimum Serial Cable Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

F-1 Entrelec RS-232/RS-485 Converter Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1

G-1 Redundant System Wiring Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

H-1 MODBUS_S Block Used as a Serial Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-1

LIST OF TABLES

TABLE AND TITLE PAGE

C-1 Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

D-1 Library Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

E-1 Control Module Serial Port Pin-Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

CG39FDI-3 CONTENTS

May 1997 iii

SIGNIFICANT CHANGES FOR REV. 2

Significant changes for rev. 2 are indicated by change bars located in the page margins. These changes arelisted here.

1.0 INTRODUCTION - This section has been updated to accommodate the QUADLOG version ofthe library. Section descriptions were updated to include the new appendices outlined below.

1.2.2 PRODUCT SUPPORT - This section has been enhanced with the addition of a telephone listingof international subsidiaries.

2.0 SOFTWARE INSTALLATION - This section has been rewritten to accommodate the differentversions of MS-Windows (i.e. Windows 3.x, Windows 95, and Windows NT).

4.0 FUNCTION BLOCKS - This section has updated graphics for the Modbus Slave(MODBUS_S) and Serial (SERIAL) function blocks. Also, two new soft list parameters(WriteSecurity and ExtendedAddress) have been added to the MODBUS_S block.

A.0 APPENDIX A, APPLICATION EXAMPLE 1 - This section has been revised with updates tographics which show examples of on-line display information.

B.0 APPENDIX B, APPLICATION EXAMPLE 2 - This section has been revised with updates to graphicswhich show examples of on-line display information.

C.0 APPENDIX C, ERROR CODES - This section has been expanded. It now lists the error code messagesthat appear at the error code (E_CODE) output of the MODBUS_S function block, a description of eachcode, and recommended user actions.

D.0 APPENDIX D, SPECIFICATIONS - This section has been updated to include the latest generalspecifications of the Modbus Slave Function Block Library.

F.0 APPENDIX F, ENTRELEC RS232/485 CONVERTER CONNECTIONS - This is a new sectionthat shows the connections needed for wiring an RS-485 foreign device to an ACM/CCM’s RS-232serial port using an Entrelec RS-232 to RS-485 converter.

G.0 APPENDIX G, REDUNDANT SYSTEM WIRING CONFIGURATION - This is a new sectionthat shows the general wiring needed for a dual Modbus network in a redundant system.

H.0 APPENDIX H, USING MODBUS_ S BLOCK AS A SERIAL ANALYZER - This is a new sectionthat describes the configuration of a MODBUS_S block for use as a serial protocol analyzer.

CONTENTS CG39FDI-3

May 1997iv

Moore Products Co. assumes no liability for errors or omissions in this document or for the application and use of information included in thisdocument. The information herein is subject to change without notice.

The Moore logo, APACS, the APACS logo, QUADLOG, the QUADLOG logo, and 4-mation are trademarks of Moore Products Co.All other trademarks are the property of the respective owners.

© Copyright 1997 Moore Products Co. All rights reserved.

CG39FDI-3 INTRODUCTION

May 1997 1-1

1.0 INTRODUCTION

The Modbus Slave Function Block Library is add-on software for use with the 4-mation™ configuration *software, version 3.00 or higher. The library software is available in both APACS and QUADLOG *® ®

versions. The APACS version (P/N 15939-624V4.xx) is for use with the Advanced Control Module (ACM) *software, version 4.01 or higher. The QUADLOG version (P/N 15939-682V3.2x) is for use with either the *Advanced Control Module Plus (ACM+) software or the Critical Control Module (CCM) software. Each *must be version 3.20 or higher. *

The library software provides 4-mation with a set of function blocks for configuring a control module tooperate as a Modbus slave.

This document describes how to identify, register, backup, and install the Modbus Slave FB Library. It alsoprovides reference information for each function block. This information is intended to be used inconjunction with Using the 4-mation Configuration Software, as well as the other documents listed insection 1.3, Related Literature. After the Modbus Slave FB Library software has been installed, most of theinformation presented in this document is also available through 4-mation’s on-line help system.

This Guide is organized into the following sections:

C Section 1, Introduction—Summarizes the information presented in this Guide, describes the softwarepackage, provides the software registration procedure, and lists reference literature to consult foradditional information.

C Section 2, Software Installation—Describes the general disk handling and backup requirements and thesoftware installation procedure.

C Section 3, Configuration—Gives a general configuration objective, refers to the needed configurationsoftware and associated literature, indicates how the function block library is accessed, and providesguidelines to carry out the MODBUS_S function block configuration.

C Section 4, Function Blocks—Details the inputs, outputs, and softlist parameters of the MODBUS_S andthe SERIAL function blocks.

C Appendix A, Application Example 1—Provides a configuration example of using a control module as aModbus slave to provide 60 floating-point (REAL) values to a Modbus master.

C Appendix B, Application Example 2—Describes a control module configured as a Modbus slave toprovide 500 BOOL values to a Modbus master. Handling of reverse data flow (Modbus master writeoperation) is also discussed briefly.

C Appendix C, Error Codes—Lists the error code messages that appear at the error code (E_CODE)output of the MODBUS_S function block whenever an error condition is encountered.

C Appendix D, Specifications—Lists general specifications for the Modbus Slave Function Block (FB)Library.

INTRODUCTION CG39FDI-3

May 19971-2

C Appendix E, Cable Connections—Shows the pin-out of control module serial ports and the minimumcable requirements for connecting to the serial port of a foreign device.

C Appendix F, Entrelec RS-232 to RS-485 Converter Connections—Details the wiring and configurationof the recommended RS-232 to RS-485 converter.

C Appendix G, Redundant System Wiring—Shows the general wiring configuration of a dual Modbusnetwork in a redundant system.

C Appendix H, Using MODBUS_S as a Serial Analyzer—Describes the configuration of a MODBUS_Sblock for use as a serial protocol analyzer.

1.1 PRODUCT DESCRIPTION

The Modbus Function Block (FB) Libraries permit the control module and the APACS/QUADLOG systemto exchange data with foreign devices that use the Modbus protocol. The Modbus RTU protocol is used byAEG Schneider Automation (formerly Gould/Modicon) RTU programmable logic controllers (PLCs) and bymany types of specialty instruments and interfaces such as analyzers, chromatographs, weigh scales, human-machine interfaces (HMIs), remote termination units (RTUs), and other distributed control systems (DCSs). Modbus RTU is a master/slave protocol in which a single master can address multiple slaves. The slavedevices do not initiate any communication; they wait for a command from the master, which requests theslave to read or write data values. The control module can be configured to be either the master or the slave,but not both from the same port.

The Modbus Slave FB Library contains the Modbus Slave (MODBUS_S) function block, which allows thecontrol module to act as a Modbus slave. The Modbus Master FB Library contains the Modbus Master(MODBUS_M) function block, which allows the control module to act as a Modbus master. To use a controlmodule as a Modbus Master, refer to the Modbus Master Function Block Library (document numberCG39FDI-2). Both libraries also contain a Serial (SERIAL) function block, which is used to initialize theModbus communications port.

The function blocks included in Modbus Slave FB Library are configured on a configuration sheet using the4-mation™ configuration software. The configuration of the MODBUS_S function block establishes, insidethe control module, a data array to hold the foreign device data. The control module configuration, anothercontrol module, or an operator interface can then access and use the foreign device data by referencing thearray element. Configuration of the SERIAL function block enables the control module’s serial port tocommunicate with the Modbus network and its foreign devices.

1.2 SOFTWARE REGISTRATION AND SUPPORT

The following subsections present guidelines for registering your software package and for contacting MooreProducts Co. for software product support.


May 1997 1-3

1.2.1 Software Registration

Before reading further, complete and mail the brief Software Registration Form included in the package. Registration will:

C Enter your software’s part number/version number and serial number in the master database of activesoftware packages

C Initiate product support

C Identify you as the person to whom information about future software enhancements and updates shouldbe sent

Without proper registration, it may be impossible to provide product support and to inform you ofenhancements and updates.

Each software update or enhancement will include a Software Registration Form so that your package’scurrent part number/version number and serial number can be recorded in the database. Additionalregistration forms are provided for subsequent users who become responsible for the software.

1.2.2 Product Support

Product support can be obtained from the Moore Products Co. Technical Information Center (TIC). TIC is acustomer service center that provides direct telephone support on technical issues related to the functionality,application, and integration of all products supplied by Moore Products Co.

To contact TIC for support, either call 215-646-7400, extension 4TIC (4842) or leave a message in thebulletin board service (BBS) by calling 215-283-4968. The following information should be at hand whencontacting TIC for support:

C Caller ID number, or name and company name

(When someone calls for support for the first time, a personal caller number is assigned. This number ismailed in the form of a caller card. Having the number available when calling for support will allow theTIC representative taking the call to use the central customer database to quickly identify the caller’slocation and past support needs.)

C Product part number, software version, and serial number, all of which are identified on the software’sdisk label

C Computer brand name, model number, and hardware configuration (types of disk drives, memory size,video adapter, etc.)

C Version number of operating system (e.g. MS-DOS 6.22, Windows 3.x, Windows 95, Windows NT)


May 19971-4

C If there is a problem with software operation:- The steps performed before the problem occurred- Any error messages displayed- A copy of the computer’s CONFIG.SYS file- A copy of the computer’s AUTOEXEC.BAT file

It would also be helpful to have the following information:- 4-mation version number- Control module ROM version- Documentation about your system’s architecture

- Information about the foreign device (e.g. company name, model number, software version, Modbus protocol implementation, etc.) to which the control module and the Modbus software are trying to communicate.

For product support outside of North America, an alternative support system is available by contacting theappropriate Moore Products Co. subsidiary:

Australia* MexicoMoore Products Co. (Australia) Pty.Ltd.* Moore Products de Mexico S.A. de C.V.Tel: (61) (2) 9319 4877* Tel: 6-11-98-58; 6-15-19-48;

* 6-15-02-62; or 6-15-02-38Canada*Moore Products Co. (Canada) Inc.*Tel: (905) 457 9638* Moore Products Co. B.V.

* Tel: (00) (31) 180 461111France*Factory Systemes, 22*Tel: (33 1) 64 61 68 68* Moore Products Co. (S) Pte.Ltd.

* Tel: (65) 299 6051India*Moore Controls Pvt. Limited*Tel: (91) (212) 770171* Moore Controls S.A. (Pty.)

* Tel: (27) 466 1673/9Italy*Moore Products Co. (Italia) S.r.l.*Tel: (39) (2) 2940 1094* Moore Products Co.(U.K.) Ltd.

* Tel: (44) (1935) 706262Japan*Moore Products Co.(Japan) K.K.*Tel: (81) (3) 5484 4390*

The Netherlands

Singapore

South Africa

United Kingdom


May 1997 1-5

1.3 RELATED LITERATURE

The following Moore Products Co. literature is available for reference:

C 4-mation, Installation and Operation (version 3.x binder number UM39-6, version 4.x binder number *UM39-11) *

C Function Block Language (version 3.x binder number UM39-7, version 4.x binder number UM39-12) *C APACS ACM Installation & Service Instruction (document number SD39ACM-2) *C QUADLOG CCM Installation & Service Instruction (document number SDQLCCM-1) *

The following vendor literature should be available as needed:

• Microsoft MS-DOS Operating System Reference• Microsoft Windows User’s GuideC Foreign Device’s Modbus Protocol Communications ManualC AEG Schneider Automation’s “Modicon Modbus Protocol Reference Guide PI-MBUS-300” *

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May 19971-6

CG39FDI-3 SOFTWARE INSTALLATION

May 1997 2-1

2.0 SOFTWARE INSTALLATION *

This section provides the procedures for making a backup copy of the Modbus Slave FB Library software,installing the software, and performing initial software set-up. The software must be installed from floppydisks to a permanent storage medium, such as the computer’s hard disk.

2.1 DISK IDENTIFICATION AND BACKUP

The Modbus Slave FB Library software is shipped on a high density (HD) 3½" floppy disk. The label on thedisk lists the product’s part number, release number, and date. It is recommended that you make backupcopies of the original disk. Make the copies using the disk copying procedure appropriate for your computer’soperating system. Once copied, safeguard the original by storing it separately from the copies. Be sure tocorrectly label and write-protect the copies.

2.2 INSTALLATION PROCEDURE

The following procedures are used to install the Modbus Slave FB Library software from a floppy drive to apermanent storage medium, such as a hard drive. The installation is performed from Windows ProgramManager or Explorer. This is accomplished with the installation program (SETUP.EXE) resident on thelibrary disk. Essentially, you are to load and run this program and respond to prompts. The prompts will bein the form of pop-up dialog boxes which will query you to enter information regarding your computersystem. The method used to run the setup program varies depending on the specific version of Windows onthe host computer. Use the appropriate procedure as needed.

IMPORTANT

An ACM/CCM configuration created before the Modbus Slave FB Library installationcan either be exported/imported to include the new function blocks, or a newconfiguration can be created and copy/paste used to place the Modbus Slave and Serialfunction blocks into it.

To install the library under Windows 3.x:

1. Insert the library disk into the floppy drive. 2. From Program Manager, select File, Run. 3. At the Run command line, enter drive:\SETUP.EXE to start and initialize the setup program.

Examples: A:\SETUP.EXE or B:\SETUP.EXE

4. When the setup program starts, you are presented with an installation screen. Pop-up dialog boxeswill prompt you to enter information about your computer. Respond as needed.

SOFTWARE INSTALLATION CG39FDI-3

May 19972-2

To install the library under Windows 95:

1. Click on the Start button, point to Settings, and then click Control Panel. 2. Double-click on the Add/Remove Programs icon. This opens the Add/Remove Program Properties

dialog box. 3. Click the Install button. This opens the Install Program From Floppy Disk or CD-ROM dialog box. 4. Insert the library disk into the floppy drive then click the Next button. This opens the Run

Installation Program dialog box. 5. Verify that the command line is displaying the path and name of the setup program, then click the

Finish button to commence installation.

Examples: A:\SETUP.EXE or B:\SETUP.EXE

6. When the setup program starts, you are presented with a series of dialog boxes that prompt you forinformation about your computer. Respond as needed.

To install the library under Windows NT:

The procedure for installing this library under Windows NT (also called Windows NT Workstation) dependson which version of this operating system you are using. For Windows NT up to and including version 3.5.1,use the procedure for Windows 3.x above. For Windows NT version 4.0 and higher, use the procedure forWindows 95 above.

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CG39FDI-3 CONFIGURATION

May 1997 3-1

3.0 CONFIGURATION

The Modbus Slave FB Library is used to configure a control module to act as a Modbus slave. In this role,the control module provides APACS/QUADLOG data in response to requests from a Modbus master. Manydevices found in the control industry act as Modbus masters, such as human-machine interfaces (HMIs),remote terminal units (RTUs), data acquisition systems, and distributed control systems. The slave controlmodule also responds to commands from the Modbus master to change (write) APACS/QUADLOG valuesmapped as Modbus addresses.

3.1 PROCEDURE

The configuration procedure for the Modbus Slave FB Library entails the same skills and knowledge neededfor the configuration of other function blocks used by either APACS or QUADLOG. The configuration isdeveloped by use of the 4-mation configuration software. Instructions for proper installation and use of 4-mation are given in the appropriate literature listed in section 1.3, Related Literature.

3.2 ACCESSING THE FUNCTION BLOCK LIBRARY

With the Modbus Slave FB Library properly installed (see section 2.0, Installation), 4-mation willautomatically include the Modbus Slave (MODBUS_S) and Serial (SERIAL) function blocks when it isstarted. These function blocks can then be selected from 4-mation’s Standard function block list (they willnot appear on the icon bar).

Use the DERIVED key and then select the Standard radio button to display the list of function blocksincluding the MODBUS_S and SERIAL blocks.

IMPORTANT

An ACM/CCM configuration created before the Modbus Slave FB Libraryinstallation can be exported/imported to include the new function blocks, or a newconfiguration can be created and copy/paste used to place the Modbus Slave andSerial function blocks into it.

3.3 GENERAL CONCEPTS

The MODBUS_S function block(s) can be configured to handle the majority of the Modbus communicationrequirements. Additional control module configuration (ladder logic, function blocks, etc.) is also needed tocreate and manipulate data arrays that provide data values to the MODBUS_S function blocks and, thus, theModbus master.

The basic MODBUS_S function block is shown in section 4.1. The Modbus slave node address is specifiedas the ADDR input. A control module can only appear as a single slave node address. The Modbus referencetype (i.e. output coil, input coil, input register or holding register), length of the data array, and scaling valuesare also entered as function block inputs. Scaling can be performed on analog values by using the ENG_LO

CONFIGURATION CG39FDI-3

May 19973-2

and HI data array inputs.

The purpose of the SERIAL function block is to setup one of the control module’s serial ports for serialcommunication with a foreign device. This function block handles the baud rate, parity, stop bits, etc. alongwith flow control, timeout, and buffer size parameters. The SERIAL block provides an ID output to bereferenced by other serial communication function blocks that use the control module serial port. Multipleserial communication function blocks, such as the MODBUS_S, can make use of a single SERIAL block.

3.4 CONFIGURATION GUIDELINES

A common application for the MODBUS_S function block is to provide APACS/QUADLOG values to aModbus master using data references that are understood by the master (for example, coils and registers). Typically, several MODBUS_S function blocks would be configured to retrieve APACS/QUADLOG valuesin the control module, such as process variables, I/O points, and calculated variables, and to map these to theModbus coil and register addresses. The Modbus master would then be able to read and, as needed, write tothose coils and registers over the Modbus protocol link.

The control module is configured to represent a single Modbus slave node address by entering a value in theADDR input of each MODBUS_S function block. The type of Modbus reference (coil, register, etc.) isdetermined by the START input.

In the Modbus system, coils are addresses from 00001 to 09999 (1 to 9999), input coils are 10001 to 19999,input registers are 30001 to 39999, and holding registers are 40001 to 49999. The NUM input thendefines how many sequential references will be provided by this MODBUS_S function block, beginning atthe START address.

The actual data values are placed in the configured DATA array, where each element generally corresponds toa Modbus coil or register. For some values, like REALs and DINTs, two registers may be used to represent asingle value, depending on the function block configuration.

Analog values in the APACS/QUADLOG system, such as REALs, DINTs, and UINTs should be mapped toinput registers (3xxxx) or holding registers (4xxxx). Discrete values, like BOOLs, should be mapped to coils(0xxxx) or input coils (1xxxx). Using a simple assignment method on a control module configuration sheet,each APACS/QUADLOG value can be transferred to a corresponding DATA array element and provided tothe Modbus master when requested. New data values, sent by the Modbus master to change Modbus valuesvia the MODBUS_S function block, also appear in the DATA array.

CG39FDI-3 CONFIGURATION

May 1997 3-3

IMPORTANT

When structuring the database in the control module acting as a Modbusslave device, it is strongly suggested that a sequential block of discretes,registers, etc. be allocated as the data to be read by the master. A sequentialblock of data will be read much more efficiently by the master, resulting inimproved performance. If necessary, use control module instructions tomove the data from scattered origins to a sequential or tightly packed groupof registers, discretes, etc. to be read by the master.

Section 4.0, Function Blocks, defines the inputs, outputs, and soft list parameters of the MODBUS_S andSERIAL function blocks used in configuring the Modbus slave. Detailed descriptions of two applications areprovided in the appendices of this Guide. Appendix A contains Application Example 1, which describes acontrol module configured as a Modbus slave that provides sixty floating point (REAL) values to a Modbusmaster. Appendix B contains Application Example 2, which describes a control module configured as aModbus slave that provides 500 BOOL values to a Modbus master. Both examples also include informationfor handling Modbus master write operations. Additional supplemental information is provided inappendices C through H as described in section 1.0, Introduction.

#

CONFIGURATION CG39FDI-3

May 19973-4

CG39FDI-3 FUNCTION BLOCKS

May 1997 4-1

4.0 FUNCTION BLOCKS *

The Modbus Slave Function Block Library provides the 4-mation configuration software with a set offunction blocks for configuring a control module (ACM/CCM) to operate as a Modbus slave. This permits anAPACS or QUADLOG system to exchange data with foreign devices that use the Modbus protocol. Modbusis a master/slave protocol in which a single master can address multiple slaves. A listing of the library blocksis presented here. Reference information pertaining to individual blocks is detailed in the sections to follow.

C Modbus Slave block (MODBUS_S)C Serial block (SERIAL)

FUNCTION BLOCKS CG39FDI-3

May 19974-2

4.1 MODBUS SLAVE FUNCTION BLOCK (MODBUS_S)

The symbol for the Modbus Slave (MODBUS_S) function block is shown above. This block allows thecontrol module to act as a Modbus slave. This section defines the inputs, outputs, and soft list parameters ofthe block.

4.1.1 Inputs

This section describes the inputs of the MODBUS_S function block.

EN Data Type: BOOL

When this ENable input is TRUE, the block is setup for continuous response to read requests orcommands from the master that are configured properly for this block. If EN is FALSE, the masterdoes not get a response for a command destined for this block.

ID Data Type: INT

A valid ID input must be configured for each MODBUS_S function block to execute. The IDoriginates from a SERIAL connect block, which can be used for multiple MODBUS_S blocks in acontrol module.

ADDR Data Type: INT

This is the Address input. Enter the Modbus slave address that is assigned to the Modbus slaveemulation running in this control module. Commands from a Modbus master must use this slaveaddress for proper communication with the control module. The control module does not respond tocommands that are not destined for the configured slave address.


May 1997 4-3

IMPORTANT

A control module can only appear as a single Modbus slave address. MultipleMODBUS_S blocks can be configured in one control module, but they must havethe same ADDR input value.

START Data Type: DINT

This input defines the starting address for the configured command. It requires a double integer(DINT) data type since valid entries are 1 (for coil 00001) to 49999 (holding register 49999) andallows for future reference types to be added.

NUM Data Type: INT

This input defines the quantity of coils or registers to be read or written by the configured command. When reading floating point or double integer values from the slave device, give careful notice to thisentry and the NumBytesPerReg Softlist entry. If the FP or DINT value is composed of two registeraddresses (NumBytesPerReg=2), the NUMber of registers configured should be twice the number ofvalues desired (see Application Example 1 in Appendix A).

DATA Data Type: Single dimension array of REAL, UDINT, DINT, STRING, UINT, WORD, orBOOL depending upon the Modbus Command number (see the Commanddescriptions above)

When receiving a command that reads data from the slave device, this array contains the actual datavalues returned in the response from the slave. When the command performs a write to change avalue in the slave, the new values are written to this array.

When declaring and handling this array, it is important to be aware of the following important rules:

C It must be a single dimensional array (e.g. DATAONE[1..100]).

C Do not use the Modbus reference type (0,1,3,4) as part of the DATA array size declaration. Forexample, if the MODBUS_S block is sourcing 50 unsigned integer registers to your master(START=40301, NUM=50), the DATA array could be declared as SLVDATA[301..400]; thatis, the 4 is omitted from the array size.

C Values communicated via Modbus are placed or extracted from the DATA array according tohow the array is declared, the value of the START input and/or the ArrayOffset soft listparameter.

If the ArrayOffset parameter is FALSE, the first Modbus value corresponds to the first DATAarray element number. In the example above, the ArrayOffset should be set FALSE so that thevalue for register 40301 is placed in the first DATA array element, in this case SLVDATA[301].


May 19974-4

Since the SLVDATA array was declared with a range 301..400, element [301] is still the firstelement even though its value is not 1.

Declaring the DATA array with element numbers that correspond to the Modbus reference mayprovide a convenient way to identify an array element number with the Modbus reference,depending upon the data type.

If the ArrayOffset parameter is TRUE, the value of the START input determines thecorresponding DATA array element number. Continuing with the example given above, if asecond MODBUS_S block was configured to soure registers 351 to 400 (START=40351,NUM=50), the same SLVDATA array could be used. However, ArrayOffset should be setTRUE so that register 40351 is placed in SLVDATA[351]. The value of the START input,ignoring the Modbus reference type, is used to determine the offset.

C When 32-bit values are handled and the slave uses two registers for one value, the number ofModbus registers required is twice the number of actual 32-bit values. Therefore, a one-to-onecorrespondence between register number and DATA array element number will not exist.

As an example using 32-bit values where NumBytesPerReg=2, if the START value is 48001and the NUM input is 100, the DATA array could be created as DATAONE[8001..8050]REALs. That is, it takes 100 registers to produce 50 floating point (REAL) values whenNumBytesPerReg=2. The composite value from registers 48001 and 48002 would be placed inDATAONE[8001], the value from registers 48003 and 48004 would be placed inDATAONE[8002], etc. The composite value for the last two registers, 48099 and 48100, wouldbe found in DATAONE[8050].

As an alternative, the register number association to the DATA array element number can beeliminated by declaring your DATA array to be [1..50] in the example above. In this manner, the10th floating point value read would be placed in DATAONE[10].

C The DATA array dimensions must encompass the range of addresses configured by the STARTand NUM inputs. For example, if the START input is 16000 (Input Coil 6000) and the NUM is200, the DATA array could be declared as INPUTS[6000..6199]. Again, note that the referencetype designator (0,1,3 or 4) is not declared as part of the array element number.

C When reading and writing Text Strings, refer to the Special Application section under ENG_LOfor details on proper DATA Array declaration.

ENG_LO Data Type: Single dimension array of REALs**

This Engineering Range Low input is used in conjunction with the ENG_HI input. Most analog values in*an APACS/QUADLOG system are of data type REAL, however, some Modbus masters cannot read and*write REAL (floating point) data values from slaves. These masters often use the standard 16-bit*unsigned integer (UINT) register value and then use local scaling to provide an engineering range. The*MODBUS_S block can be configured to convert REAL values to UINTs so they can be properly handled*by the Modbus master.*


May 1997 4-5

The MODBUS_S function block assumes a raw data range of 0 (0%) to 65535 (100%) for a 16-bit *unsigned integer value. Based upon the configured ENG_LO and ENG_HI array element values, each *DATA array element is scaled by the linear equation y = mx + b, where y is the scaled REAL value and x *is the raw register value. *

*For example, if ENG_LO=0.00 and ENG_HI=100.00, a REAL value of 50.00 is scaled to produce a *register value of 32768. The associated Modbus master must then use its own scaling mechanism to *produce an engineering range value, in this case, converting it back to 50.00. This can be accomplished *as follows: *

*DATA[a] = [(ENG_HI[a] - LO[a] ) / (65535)] (register value) + ENG_LO[a] *

*Where: [a] is the array element number. *

**

IMPORTANT **

ENG LO and ENG_ HI array inputs should not be configured when 32-bit values *can be handled by the Modbus master. These scaling factors are primarily intended *for use when converting an APACS/QUADLOG REAL to a 16-bit value (unsigned *integer) because the Modbus master does not support this data type. *

*

ENG_LO Special Application - Accessing Text Strings

Data Type: INT (with STRING DATA Array)

When a Modbus master reads a text string from a Modbus slave, the DATA array must be declaredwith a STRING data type and ENG_LO with an INT data type. Each text string in the (ACM/CCM)Modbus slave has a certain character length that you define. Typically, each Modbus register holdstwo characters.

Each text string corresponds to a STRING array element in your MODBUS_S DATA array. Thenumber of characters for each text string and, therefore, each STRING array element is specified bythe corresponding array element in the ENG_LO array. The ENG_LO array should be declared asdata type INT with the same number of elements as the DATA array. The value in the ENG_LOarray element specifies the number of characters for the corresponding STRING. For example,assume your Modbus slave device has three text strings, as shown below, to be read into the controlmodule. The START input still specifies the starting Modbus register, in this case, 40325. TheDATA array is declared as SLV1TXT1[1..3], STRING data type. The ENG_LO array is declared asLENGTH1[1..3], INT data type.

SLAVE TEXT DATA FB DATA READ RESULTStarting Register 40325 START = 40325Text String A: 8 characters (4 registers) LENGTH[1] = 8 SLV1TXT[1]Text String B: 16 characters LENGTH[2] = 16 SLV1TXT[2]Text String C: 4 characters LENGTH[3] = 4 SLV1TXT[3]


May 19974-6

When the Modbus master sends a Modbus command to the slave (usually Function Code 03) to read14 registers starting at 40325, the NUM input does not need to be configured because theMODBUS_S block calculates the correct number of registers for you (based on two characters perregister, the ENG_LO array values, and DATA array length).

ENG_HI Data Type: Single dimension array of REALs

This is the Engineering Range High input. It is used in conjunction with the ENG_LOinput. Refer to the description of the ENG_LO input for usage information.

4.1.2 Modbus Function Codes

The MODBUS_S function block does not have a CMD (command) input because, as a slave, it does not*execute any commands; it only responds to commands issued from the Modbus master. The Modbus*function code commands supported by the MODBUS_S function block are described in this section. Consult*the master device’s Modbus implementation regarding implemented function codes, valid reference types and*ranges, maximum number of values read in a single command, etc. to ensure compatibility.*

01 - Read Coil Status

DATA Array: BOOL

Reads Modbus reference type Output Coil (addresses 00001 to 09999 decimal). Note that theSTARTing address for MODBUS_S function block does not have the leading zeroes (e.g. Coil00001 would be entered as 1). Maximum coils read by a function block using Command 01 is 2000.

02 - Read Input Status

DATA Array: BOOL

Reads Modbus reference type Input Coil (addresses 10001 to 19999 decimal). The maximum coilsread by a function block using Command 02 is 2000.

03 - Read Holding Registers

DATA Array: WORD, INT, UINT, REAL, DINT, UDINT, STRING, or BOOL (lowest number coil isfirst BOOL element in array)


May 1997 4-7

Reads Modbus reference type Holding Register (addresses 40001 to 49999 decimal). Maximumregisters read by a function block using Command 03 are:

126 DATA Array: WORD, INT, UINT, BOOL, REAL, DINT, or UDINT (NumBytesPerReg=2)

63 DATA Array: REAL, DINT, or UDINT (NumBytesPerReg=4)

04 - Read Input Registers


Reads Modbus reference type Input Register (addresses 30001 to 39999 decimal). Maximumregisters read by a function block using Command 04 are:

126 DATA Array: WORD, INT, UINT, BOOL, REAL, DINT, or UDINT(NumBytesPerReg=2)

63 DATA Array: REAL, DINT, or UDINT (NumBytesPerReg=4)

05 - Force Single Coil

DATA Array: BOOL

Processes a command from a Modbus master to change the state of a single 0xxxx coil.

06 - Preset Single Register


Processes a command to change the value of a single 4xxxx holding register.

08 - Loopback Test

One of the properly configured MODBUS_S blocks automatically handles this command by re-transmitting the received data from the Modbus master.

NOTE

The MODBUS_S implementation of the Loopback Test requires that the first word ofdata, after the diagnostic code portion, indicate the number of words (registers) being


May 19974-8

transmitted. For example, when the master sends a Loopback Test command with Diag.Code = 00 00, followed by 6 registers of data, the value in the first data register shouldbe 00 06.

15 - Force Multiple Coils

DATA Array: BOOL

Processes a command to change the state of multiple 0xxxx coils.

16 - Preset Multiple Registers


Processes a command to change the value of multiple 4xxxx holding registers. When changing thevalue of a floating point or double integer address that uses two consecutive registers, this commandmust be used (Function Code 06 does not work).

17 - Report Slave I.D.

DATA Array: WORD, INT, UINT

One of the configured MODBUS_S function blocks will automatically handle this command byresponding with nine bytes of data, similar to a Modicon 984 PLC.

BYTE CONTENTS1 09 Slave ID2 FF Run Indicator3 00 not used, refer to PI-MBUS-3004 00 not used, refer to PI-MBUS-3005 00 not used, refer to PI-MBUS-3006 00 not used, refer to PI-MBUS-3007 A0 pwr on, run, mem protect off, battery OK

(may not reflect actual ACM conditions)8 00 not used, refer to PI-MBUS-3009 00 not used, refer to PI-MBUS-300

4.1.3 Outputs

This section describes the outputs of the MODBUS_S function block.


May 1997 4-9

NDR Data Type: BOOL

When a command is received through the serial port for the configured function block, the booleanoutput will toggle from FALSE to TRUE and then back to FALSE the next scan. This can be usedto inform other logic that new data has been received or a command has completed.

ERROR Data Type: BOOL

An error condition received by this block causes the output to go TRUE for one control module scan. If desired, this output can be used to indicate to outside logic that an error has occurred and to assistin troubleshooting communication problems.

E_CODE Data Type: INT

This output provides a string description of an error condition. A value of 0 at the output indicatesno errors. Other error values are described in Appendix C.

STATE Data Type: INT

This output provides an integer that represents the current communication status of the functionblock as follows:

1 = Idle2 = Building a command3 = Sending a command4 = Waiting for a response

4.1.4 Soft List Parameters

This subsection provides specifications and important supplementary information for the MODBUS_Sfunction block soft list parameters.

NumBytesPerReg Data Type: INT (valid values are 2 and 4)

This parameter configures the function block to handle each register as either a 2-byte entity or a 4-byte entity (a byte is 8 bits). When the MODBUS_S block is providing a 32-bit value to the master,the DATA array should be configured as REAL, DINT, or UDINT as appropriate. Some slaves, likeModicon PLCs, use two consecutive registers to represent a single 32-bit value, while others use oneregister. For proper reading (and writing) of data values, this parameter must be set correctly. Inaddition, the byte ordering is very important in determining a 32-bit value. This characteristic ishandled by the ModiconByteOrder parameter discussed below.


May 19974-10

2 Registers for one 32-bit value: NumBytesPerReg=21 Register for one 32-bit value: NumBytesPerReg=4

NOTE

The NumBytesPerReg parameter is ignored unless the DATA array is configuredas either REAL, DINT, or UDINT.

ModiconByteOrder Data Type: BOOL

When this parameter is TRUE, the MODBUS_S function block assumes that the byte ordering for32-bit floating point values is similar to Modicon PLCs. That is, a Modicon 32-bit value is sent astwo registers (NumBytesPerReg=2) and the transmitted byte order is:

Register x = bytes 1 and 0, Register x+1 = bytes 3 and 2

For example, a floating point value in a Modicon PLC-compatible slave device is stored in Registers40001 and 40002. The current value is 100.00. This value would be transmitted via Modbusprotocol as:

40001 4000200 00 42 C8

Using the standard IEEE single-precision floating point format, this would be interpreted as the value100.00 REAL in the APACS or QUADLOG system.

When this parameter is FALSE, the MODBUS_S function block expects the byte order to be “word-swapped” from the Modicon byte order. That is, the value above would be transmitted as:

40001 4000242 C8 00 00

NOTE

The ModiconByteOrder parameter is ignored unless the DATA array is configuredas either REAL, DINT, or UDINT. The Byte Order will also operate on values thatuse four bytes per register.

ArrayOffset Data Type: BOOL

When this parameter is FALSE, the data values correspond to the first element location of thedeclared DATA array, regardless of the START input value. When ArrayOffset is set to TRUE, anoffset is used when placing values in the DATA array. This offset process actually causes values tobe placed in the array according to the configured START input value. For example, if the STARTvalue is 41626, ArrayOffset=TRUE, and the DATA array is declared as UINT data type


May 1997 4-11

(DATA_ONE[501..750]), the values from a register read command are placed in the DATA_ONEarray, starting at element [626] not the first element [501].

This feature is often useful in applications where several full-capacity MODBUS_S blocks are goingto bring data into the control module and build a single DATA array. For example, MODBUS_S_1reads registers 41501 to 625 and places data in DATA_ONE[501] to [625]. MODBUS_S_2 readsregisters 41626 to 750 and places data in DATA_ONE [626] to [750]. The complete range ofvalues can then be accessed by an APACS or QUADLOG client by reading array DATA_ONE. TheArrayOffset=TRUE must be set for MODBUS_S_2).

Default: FALSE

WriteSecurity Data Type: BOOL

When this parameter is TRUE and the security is enabled to prevent data writes, Register and Coilwrites are rejected.

Default: TRUE

ExtendedAddress Data Type: BOOL

When this parameter is FALSE, the valid address ranges are defined as follows:

00001-09999 Read/Write Coils10001-19999 Read Input Status30001-39999 Read Input Registers40001-49999 Read/Write Holding Registers

When this parameter is TRUE, the valid address ranges for extended addressing are defined asfollows:

000001-065535 Read/Write Coils100001-165535 Read Input Status300001-365535 Read Input Registers400001-465535 Read/Write Holding Registers

Default: FALSE

Version Data Type: STRING

This parameter is intended to specify the minimum APACS or QUADLOG version compatibilitylevel for using this function block. Its use is flexible. For example, you can use it to enter the controlmodule firmware revision number, 4-mation’s software version number, or both. Once entered, youcan determine compatibility by checking a software number against the number(s) in this parameter.


May 19974-12

BOOL BOOL

SERIAL

NDRERROR

E_CODE

EN

IDINTBOOL

INT


May 1997 4-13

4.2 SERIAL FUNCTION BLOCK (SERIAL)

The symbol for the Serial (SERIAL) function block is shown above. This block is used to initialize theModbus communications port. Specifically, it enables the control module’s serial port to communicate withthe Modbus network and its foreign devices. This section defines the input/output nubs and the soft listparameters of the SERIAL function block.

The following subsections provides specifications and important supplementary information for all theSERIAL function block input/output nubs.

4.2.1 Input

This section describes the input of the SERIAL function block.

EN Data Type: BOOL

When this input is set to FALSE, the SERIAL block is not active. When TRUE, the function blockwill generate an ID output, which is to be used by the other serial communication function blocks. When active, the function block handles requests from the communication function blocks andexternal devices connected to the serial port.

4.2.2 Outputs

This section describes the outputs of the SERIAL function block.

NDR Data Type: BOOL

Reserved for future use.


This output is TRUE when the last transmitted or received message contained an error. Moreinformation about the error is provided by the E_CODE output.


May 19974-14

E_CODE Data Type: INT

A zero output indicates that no general serial port errors exist. Error conditions particular to a serialport command will be passed to the appropriate communication function block (e.g. MODBUS_S),which has its own E_CODE output.

ID Data Type: INT

If the SERIAL block is functioning, it provides an ID output which must be used by other serialcommunication function blocks as their ID input. An output of 0 indicates the SERIAL block is notfunctioning.

4.2.3 Soft List Parameters

This subsection provides specifications and important supplementary information for the SERIAL functionblock’s soft list parameters.

BaudRate Data Type: UDINT

This parameter sets the communication baud rate between the control module and the foreign serialdevice. The baud rates must be the same for all the serial communication devices.

Valid Entries: 110, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200,125000, 143000, 170000, 200000, 250000

Default: 9600

DataBits Data Type: UINT

The number of data bits used to represent a character must be specified. For Modbus, the data bitsshould be set to 8.

Valid Entries: 7, 8

Default: 8


May 1997 4-15

Parity Data Type: UINT

The parity mode must be the same for all serial communication devices. Traditional Modbus devicesuse even parity but be sure to check the foreign device’s documentation.

Valid Entries: 0 = None, 1 = Odd, 2 = Even

Default: 0 = None

StopBits Data Type: UINT

The number of stop bits used for a serial transmission must be specified.

Valid Entries: 1, 2

Default: 1

FlowControl Data Type: UINT

Flow control specifies what type of hardware handshaking will be used between the serialcommunication devices. If the options below do not satisfy your application, you may have tohardwire the necessary handshaking lines. Refer to Appendix E for typical cable pin-outs.

Valid Entries: 0 = RTS (Pin 8) held asserted1 = RTS asserted when control module transmits2 = Full RTS/CTS operation3 = RTS held asserted with CTS observed before transmitting

Default: 0

IMPORTANT

When using a FlowControl setting other than 0, the control module serial port DataCarrier Detect (DCD) input, pin 4, must be connected to a logic TRUE pin from theModbus device serial port, such as a DCD output or a Data Terminal Ready (DTR)signal. If the Modbus device does not have this signal, pin 4 of the control moduleserial port can be tied back to pin 8, the Request to Send (RTS) output.


May 19974-16

Timeout Data Type: UINT

When a control module initiates a serial transmission, it waits for the specified period of time for aresponse from the foreign device before indicating a timeout.

Valid Entries: 0 to 65535 (time base is milliseconds)

Default: 3000 (3.0 seconds)

ReceiveBufSize Data Type: UINT


TransmitBufSize Data Type: UINT


SIM_RackNum Data Type: UINT


SIM_SlotNum Data Type: UINT


PortNum Data Type: UINT

This parameter should be set to the control module serial port number connected to the Modbusmaster device.

Valid Entries: 1 to 8

Default: 2

Version Data Type: STRING

This parameter is intended to specify the minimum APACS or QUADLOG version compatibilitylevel for using this function block. Its use is flexible. For example, you can use it to enter the controlmodule firmware revision number, 4-mation’s software version number, or both. Once entered, youcan determine compatibility by checking a software number against the number(s) in this parameter.


May 1997 4-17

#


May 19974-18

SLV_EX1MODBUS_S

EN

ID

ADDR

START

NUM

DATA

ENG_LO

ENG_HI

-

-

-

TRUESLV_EX1_EN -

2ID1 -

10SLV_ADDR10 - 45001R45001 -

120NUM_120 -

SLVDATA1 -

-

-

NDR

ERROR

E_CODE

CG39FDI-3 APPENDIX A — APPLICATION EXAMPLE 1

May 1997 A-1

A.0 APPENDIX A — APPLICATION EXAMPLE 1 *

In this example, the control module operating as Modbus slave device address 10, provides 60 REAL valuesto a Modbus master. The Modbus master handles a single floating point value (REAL) as two Modbusregisters, with a byte order similar to a Modicon PLC. Therefore, the MODBUS_S block is configured witha NUMber of registers that is twice the number of DATA array elements (120 registers for 60 floating pointvalues).

Because the block is using 4xxxx type registers, the master must use Modbus function code 03 to readregisters and Code 16 to write registers (and write two registers for one FP value). Figures A-1, A-2, and A-3 show the various configuration parameters associated with this example.

The ENable input is set TRUE by the SLV_EX1_EN input to the MODBUS_S function block, which allowsthe block to respond to properly configured commands from the Modbus master. The ID1 input value comesfrom the SERIAL block that handles communication on the control modules’s serial port 2. The controlmodule is configured to appear as slave address 10, and the starting register address for this block is 45001as set by the R45001 variable. This block will respond to read (or write) commands for Modbus registers inthe range from 45001 to 45120, as determined by the START and NUM inputs.

FIGURE A-1 MODBUS_S Configuration Showing On-line Data for Example 1

65.9

PV1100.0

PV2200.0

PV3250.0

PV4275.0

PV5350.0

PV6777.56

PV7

65.9

SLVDATA1[5001]100.0

SLVDATA1[5002]200.0

SLVDATA1[5003]250.0

SLVDATA1[5004]275.0

SLVDATA1[5005]350.0

SLVDATA1[5006]777.56

SLVDATA1[5007]

APPENDIX A — APPLICATION EXAMPLE 1 CG39FDI-3

May 1997A-2

The data values that are provided to the Modbus master correspond to actual variables in the control moduleor elsewhere in the APACS/QUADLOG system. The values might originate from I/O modules or othervariables on an ACM/CCM configuration sheet. These values can be provided to the Modbus master as“registers” by assigning them to elements in the SLVDATA1 array. An example of this assignment is shownin Figure A-2.

The value for APACS /QUADLOG variable PV1 will be assigned to the variable in the cell to the right, inthis case, the variable SLVDATA1[5001]. This element of the SLVDATA1 array corresponds to Modbusregisters 45001 and 45002. As a result, when the Modbus master asks for two registers starting at 45001, itwill receive the PV1 value in floating point format. Similar assignments are made for the other arrayelements.

FIGURE A-2 DATA Array Element Assignment

A.1 HANDLING WRITES FROM THE MODBUS MASTER

If it is desired to have the Modbus master change an ACM/CCM value, two options are available. A portionof the SLVDATA1 array can be used for write-only registers that will contain the new value sent by theModbus master. For example, Registers 45101 to 45120 (which correspond to SLVDATA1[5051] to[5060]) could be set aside as write-only elements; that is, no assignment is made from APACS/QUADLOGvariables to these elements. In fact, the opposite would normally occur, the array element containing the newvalue would be assigned to an APACS/QUADLOG variable in the cell to the right (see Figure A-3.) Anotheroption would be to configure another MODBUS_S function block and another DATA array for handlingwrites from the master.

65.9

SETPOINT_A100.0

SETPOINT_B200.0

SETPOINT_C250.0

SETPOINT_D275.0

SETPOINT_E350.0

SETPOINT_F777.56

SETPOINT_G

65.9

SLVDATA1[5051]100.0

SLVDATA1[5052]200.0

SLVDATA1[5053]250.0

SLVDATA1[5054]275.0

SLVDATA1[5055]350.0

SLVDATA1[5056]777.56

SLVDATA1[5057]

CG39FDI-3 APPENDIX A — APPLICATION EXAMPLE 1

May 1997 A-3

FIGURE A-3 Register Writes

#

APPENDIX A — APPLICATION EXAMPLE 1 CG39FDI-3

May 1997A-4

SLV_EX2MODBUS_S

EN

ID

ADDR

START

NUM

DATA

ENG_LO

ENG_HI

-

-

-

TRUESLV_EX2_EN -

2ID1 -

10SLV_ADDR10 -

1O00001 -

500NUM_500 -

COIL_RW1 -

-

-

NDR

ERROR

E_CODE

CG39FDI-3 APPENDIX B — APPLICATION EXAMPLE 2

May 1997 B-1

B.0 APPENDIX B — APPLICATION EXAMPLE 2 *

In this example, the same control module appearing as Modbus slave 10 will be configured to provide 500BOOL values to the Modbus master. BOOL variables in the APACS or QUADLOG system would typicallybe handled as Modbus “coils,” that is, references of the 0xxxx type. The “coils” may actually be theStandard Discrete Module Plus (SDM+) or Critical Discrete Module (CDM) discrete inputs/outputs orBOOL elements in a ladder logic diagram.

The Modbus master will use function code 01 to read the coils and Codes 5 or 15 to write coils. Figures B-1,B-2, and B-3 show the various configuration parameters associated with this example.

The ENable input is set TRUE by the SLV_EX2_EN input to the MODBUS_S block, which allows the blockto respond to properly configured commands from the Modbus master. The ID1 input value comes from theSERIAL block that handles communication on the ACM/CCM’s serial port 2. The ACM/CCM is configuredto appear as slave address10 and the starting coil address for this block is 1 as set by the O00001 variable. This block will respond to read (or write) commands for Modbus coils in the range from 00001 to 00500, asdetermined by the START and NUM inputs.

FIGURE B-1 MODBUS_S Configuration Showing On-line Data for Example 2

TRUE

MTR1_RUNTRUE

MTR2_RUNFALSE

MTR3_RUNFALSE

TANK1_HIFALSE

TANK1_HIHITRUE

TANK1_FEED

TRUE

COIL_RW1[1]TRUE

COIL_RW1[2]FALSE

COIL_RW1[3]FALSE

COIL_RW1[4]FALSE

COIL_RW1[5]TRUE

COIL_RW1[6]

APPENDIX B — APPLICATION EXAMPLE 2 CG39FDI-3

May 1997B-2

The 500 BOOL values (coils 1 to 500) are placed in the DATA array COIL_RW1. This array must bedefined as a one-dimensional BOOL array from 1 to at least 500. The MODBUS_S function block uses thearray element number as a reference for handling each data value. In this case, there will be a one-to-onecorrespondence between the Modbus coil number and the COIL_RW1 array element. For example, the valuefor coil 465 will be found in COIL_RW1[465].

The data values that are provided to the Modbus master correspond to actual variables in the ACM/CCM orelsewhere in the APACS/QUADLOG system. The values might originate from I/O modules or othervariables on a configuration sheet. These values can be provided to the Modbus master as “coils” byassigning them to elements in the COIL_RW1 array. An example of this assignment is shown in Figure B-2.

The value for APACS/QUADLOG variable MTR1_RUN will be assigned to the variable in the cell to theright, in this case, the variable COIL_RW1[1]. This element of the COIL_RW1 array corresponds toModbus coil 00001. As a result , when the Modbus master asks for coil 00001, it will receive the run statusfor MOTOR1. Similar assignments are made for the other array elements.

FIGURE B-2 DATA Array Element Assignment

B.1 HANDLING WRITES FROM THE MODBUS MASTER

In this example, coils 401 to 500 have been pre-determined to handle write commands from the Modbusmaster. Therefore, when the master wants to change the state of a BOOLean value in the ACM/CCM, suchas an SDM+/CDM output, it would write to the coil that corresponds to that DATA array element.

In Figure B-3, an assignment is made between COIL_RW1[401] and the channel 5 output of theSDM+/CDM in Rack 2, Slot 6. When the Modbus master writes to coil 00401, the ACM/CCMconfiguration will transfer this value to the SDM+/CDM output. A similar assignment is made for other coilsto which the Modbus master will write.

TRUE

SDMR2S6C5TRUE

SDMR2S6C6FALSE

SDMR2S6C7FALSE

SDMR2S6C8FALSE

SDMR2S6C9

TRUE

COIL_RW1[401]TRUE

COIL_RW1[402]FALSE

COIL_RW1[403]FALSE

COIL_RW1[404]FALSE

COIL_RW1[405]

CG39FDI-3 APPENDIX B — APPLICATION EXAMPLE 2

May 1997 B-3

In typical applications, the Modbus master only writes at the request of an operator or as the result of anautomatic trigger (alarm, limitswitch, etc). In other words, writes from the master to the slave (controlmodule) usually occur much less frequently than read operations.

FIGURE B-3 Coil Writes

#

APPENDIX B — APPLICATION EXAMPLE 2 CG39FDI-3

May 1997B-4

CG39FDI-3 APPENDIX CS MODBUS ERROR CODES

May 1997 C-1

C.0 APPENDIX C — ERROR CODES *

The error code (E_CODE) output from the Modbus Slave (MODBUS_S) function block provides a stringthat lists one or more of the following error code messages listed in Table C-1.

The E_CODE output clears with each execution of the block. To view the string in 4-mation’s on-line mode,use its Variable Control function to set the block’s Request (REQ) and Continuous (CONT) inputs toFALSE. Then, toggle the REQ input TRUE (do not pulse the input). The block executes once and the errorstring can be read until the REQ input is changed.

TABLE C-1 Error Codes

ERROR CODE DESCRIPTION OR RECOMMENDED(E_CODE) POSSIBLE CAUSE ACTION

03 Backup_Confirmation_Failed C A message was received Check all cables, signalby only one side of a converters (RS-422/RS-232),redundant pair. or modems used.

C A message was discarded.

C There is a cable or signalconverter problem.

04 Checksum_Problem C A partial message was Check source of message forreceived. proper setup. Check hardware

C There was a CRC error inthe message.

C An unknown message wasreceived.

connections.

06 Message_Problem C This is a loopback message Check all cables, signalfailure. converters (RS-422/RS-232),

C There is a possiblecommunication hardwareproblem.

or modems used.

APPENDIX C S MODBUS ERROR CODES CG39FDI-3

May 1997C-2

TABLE C-1 Error Codes (Continued)


07 Transmit_Busy The serial port is busy servicing No action required if multipleanother function block. function blocks are configured

for one serial port.

08 Old_Message_Removed C A message was discarded C Check the source offrom the serial port that was message for proper setup.not serviced within threecontroller scans. C Use a protocol analyzer to

C Possibly, a MODBUS_S additional information.block was not configured tohandle this message. C Verify the MODBUS_S

decipher the message for

block configuration.

09 General_Uart_Problem C There is a problem with the C Check for multipleACM/CCM’s serial port. SERIAL blocks using one

C There is a conflictingconfiguration using the same C Check for conflictingserial port. function blocks using the

C An attempt was made to usea serial port other than 1 or2.

serial port.

same serial port.

10 Re_Initializing_Port A MODBUS function block is If this code persists, check forreinitializing because of a changing inputs or soft listconfiguration change. parameters on MODBUS

function blocks.

11 No_ID_Present The ID input of a MODBUS Configure the ID input of thefunction block is not configured MODBUS block as the outputor zero. This would be a normal of the SERIAL block andcode if you choose to disable a enable the SERIAL block.set of function blocks so they donot use a particular serial port.




May 1997 C-3

12 Invalid_Range_Inputs C The ENG_LO or ENG_HI Check for properinputs are not configured configuration of the ENG_LOproperly. These inputs and ENG_HI inputs. Seeshould only be configured section 4.1.1, Inputs.with a REAL array and twobytes per register.

C The span is equal to zero.

C The string size is greaterthan 255 characters.

C The ENG_HI input wasconfigured using signedinteger conversion.

13 Default_Message_Problem An unknown Modbus command Check the sending device.was received.

14 Array_Problem On the MODBUS block, either Check the configuration of thethe DATA, ENG_LO, or MODBUS block’s ENG_LO,ENG_HI input array is not ENG_HI, and DATA inputs. configured properly. Arrays See section 4.1.1, Inputs.must be one dimensional. If theinput array is a string array, theENG_LO input requires an INTarray. The ENG_LO andENG_HI arrays must have thesame number of elements as theDATA array.

15 Array_DataType_Problem The DATA input array variable Verify the MODBUS block’stype is invalid. DATA input with respect to

its CMD, START, and NUMinputs. See section 4.1.1,Inputs.

18 Max_Size_Exceeded The NUM input exceeds the Verify theMODBUS’s NUMmaximum allowed for the input based on the DATADATA and CMD inputs. input variable type and CMD

input. See section 4.1.1,Inputs.




May 1997C-4

21 Invalid_Inputs The function code specified on Verify the MODBUS block’stheMODBUS block’s CMD CMD and START inputs. Seeinput is not compatible with the section 4.1.1, Inputs.START input’s address range.

22 Invalid_Command The MODBUS block’s CMD Verify the CMD input isinput is invalid. supported by the MODBUS

function block.

23 Timeout_Error The Modbus device did not Use a protocol analyzer torespond within the configured verify communicationstime-out period. between the

APACS/QUADLOG systemand the Modbus device.

24 Unknown_Exception_Received The MODBUS_M block has C Check the source ofreceived an exception response message for proper setup.with an unsupported exceptioncode. C Use a protocol analyzer to

decipher the message foradditional information.

25 Invalid_Address The MODBUS block’s START Verify the START, NUM andinput address may be invalid. DATA inputs for validThe START and NUM input address ranges. See sectionvalues may not match the 4.1.1, Inputs.DATA, ENG_LO or ENG_HIarray sizes.

28 CTS_Lost_During_Transmission When using FlowControl Monitor serial options 2 or 3, the CTS line communications parameterswent low before transmission and check modem if problemwas completed. persists.

29 Unknown_TX_Error This is an unknown serial port Check for misconfiguration ofdriver transmission problem. serial port, bad wiring or

incompatible communicationparameters (e.g. baud rate,parity, etc).




May 1997 C-5

30 Unknown_RX_Error This is an unknown serial port Check for misconfiguration ofdriver reception problem. serial port, bad wiring or

incompatible communicationparameters (e.g. baud rate,parity, etc).

31 Illegal_Function_Exception The Modbus slave device does Verify that the function codenot understand the function used is supported by thecode. Modbus slave device.

32 Illegal_Data_address_Exception The starting or ending Modbus Verify that the value used isaddress, data register, or coils is within the defined range.out of range.

33 Illegal_Data_value_Exception C An illegal data value was C Correct the data value.written.

C A coil or register write failed block’s security settings.for security reasons.

C Check the MODBUS_S

34 Connection_Lost The MODBUS_M block has C Check all cables, signallost contact with its Modbus converters (RS-422/RS-slave device. 232), or modems used to

connect to the slavedevice.

C Check the Modbus slavedevice for properoperation.

#


May 1997C-6

CG39FDI-3 APPENDIX DS MODBUS LIBRARY SPECIFICATIONS

May 1997 D-1

D.0 APPENDIX D — SPECIFICATIONS *

General specifications for the Modbus_S Function Block Library are listed in Table D-1. Where applicable,default values are shown in bold type.

TABLE D-1 Library Specifications

ITEM SPECIFICATION

Library Software Part Numbers APACS 15939-624V4.00 Modbus SlaveQUADLOG 15939-682V3.20 Modbus Slave

Note that the Vx.xx suffix refers to the software version number. Itwill differ for later versions.

Required 4-mation Version 3.00 or later

Electrical I/O Port RS232 (Other physical layers can be accommodated with externalconverters, such as RS422 for multi-drop applications). ForRS422/RS485, use 4-wire only.

Transmission Mode Modbus RTU (binary)

Baud Rate 110, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600,115200, 125000, 143000, 170000, 200000, 250000

Start Bits 1

Data Bits 7 or 8

Parity Odd, Even, Space, Mark, or None

Stop Bits 1 or 2

Error Checking CRC-16

Slave Address 1 to 247

Supported Function Codes 01 - Read Coil Status 02 - Read Input Status03 - Read Holding Registers 04 - Read Input Registers05 - Force Single Coil 06 - Preset Single Register08 - Loopback Test 15 - Force Multiple Coils16 - Preset Multiple Registers 17 - Report Slave I.D.65 - Coil Status Read/Write * 66 - Holding Register Read/Write*

* MODBUS_M only

APPENDIX DS MODBUS LIBRARY SPECIFICATIONS CG39FDI-3

May 1997D-2

TABLE D-1 Library Specifications (Continued)

ITEM SPECIFICATION

Supported Address Types 00001-09999 Read/Write Coils10001-19999 Read Input Status30001-39999 Read Input Registers40001-49999 Read/Write Holding Registers

Extended Addressing:000001-065535 Read/Write Coils100001-165535 Read Input Status300001-365535 Read Input Registers400001-465535 Read/Write Holding Registers

Device Data Types Boolean Word Signed IntegerUnsigned IntegerDouble Signed IntegerDouble Unsigned IntegerFloating Point (2-register and 1-register formats; two different byteorders)String

#

ACM /CCM Serial Port (1 or 2)

Received Data RDTransmitted Data TDSignal Ground SGClear to Send CTSRequest to Send RTSData Set Ready DSRData Terminal Ready DTRData Carrier Detect DCD

TD Pin 2 Pin 3

DCD Pin 4Signal Common Pin 5

CTS Pin 7RTS Pin 8

Foreign Device Serial Port

RD

CG39FDI-3 APPENDIX ES CABLE CONNECTIONS

May 1997 E-1

E.0 APPENDIX E — CABLE CONNECTIONS

The pin-out for a control module serial port (DB9 female) is shown in Table E-1. As a minimum, the cablebetween the control module serial port and the foreign device will require TD, RD, and SG as shown inFigure E-1. The foreign device may require additional handshaking signals for proper operation (consult theforeign device documentation.) The FlowControl soft list parameter of the SERIAL block may also be usefulin selecting the proper handshaking mode, or these signals may have to be tied back to the foreign device(RTS to CTS, and DTR to DSR and DCD) as shown in Figure E-1.

TABLE E-1 Control Module Serial Port Pin-Out

PIN # DESCRIPTION DIRECTION

1 No Connection

2 Transmitted Data (TD) Output

3 Received Data (RD) Input

4 Data Carrier Detect (DCD) Input

5 Signal Ground (SG) N/A

6 No Connection

7 Clear to Send (CTS) Input

8 Request to Send (RTS) Output

9 Ring Indicator (RI) Input

FIGURE E-1 Minimum Serial Cable Requirements

APPENDIX ES CABLE CONNECTIONS CG39FDI-3

May 1997E-2

NOTE

The control module’s serial port pin-out is not the same as that typically found on apersonal computer. The control module’s serial port is a DB9 female connection,using different pins than a PC for transmitting (TD) and receiving (RD) data.

When using a FlowControl setting other than 0, the control module’s serial portData Carrier Detect (DCD) input, pin 4, must be connected to a logic TRUE pinfrom the Modbus device serial port, such as a Data Carrier Detect (DCD) output ora Data Terminal Ready (DTR) signal. If the Modbus device does not have thissignal, pin 4 of the control module can be tied back to pin 8, the Request to Send(RTS) output.

#

RS-232 to RS-485ConverterDIN rail mount500v Isolation

V+

V-

0V

P+

5V

P-

L

G

J

M

K

B

E

C

A

D

Tx+Rxd

Tx-Txd

Rx+CTRL

Rx-0V

SignalCommon

(0V)

APACS/QUADLOGsupports

4-wire interface only

EntrelecP/N 84233-11

Moore Products Co.P/N 16055-395

COM

+24VDC < 100ma

DS9

Txd

Rxd

RTS

SignalCommon

ACM/

SERIALPORT

2

3

8

5

Notes: 1, 2, 3, 4, 5, 6

NOTES:1. Internal Jumper Rt set to 220 Ohms2. Internal Jumper R set to ON3. Internal Jumper E set to ON/OFF4. All RS-485 Slave devices must be wired in parallel.5. Arrows on lines denote signal direction.6. When RTS is not available, (i.e. Foreign Device side) Jumper M to L on converter.7. Shield must be connected to the metal connector shell.8. J to F connection has been provided inside the Entrelec converter.

Note: 7Note: 4

FOREIGNRS-485DEVICE

Rx+

Rx-

Tx+

SignalCommon

Tx-

FNote: 8

CCM

CG39FDI-3 APPENDIX F—ENTRELEC RS232/485 CONVERTER CONNECTIONS

May 1997 F-1

F.0 APPENDIX F — ENTRELEC RS232/485 CONVERTER CONNECTIONS *

Cable connections needed to interface an RS-485 foreign device to the ACM/CCM RS-232 serial port bymeans of the Entrelec RS232/485 Converter are shown in Figure F-1. This converter is recommended by andavailable from Moore Products Co.

FIGURE F-1 Entrelec RS-232/RS-485 Converter Cable Connections

APPENDIX F—ENTRELEC RS232/485 CONVERTER CONNECTIONS CG39FDI-3

May 1997F-2

CG39FDI-3 APPENDIX G—REDUNDANT SYSTEM WIRING CONFIGURATION

May 1997 G-1

G.0 APPENDIX G — REDUNDANT SYSTEM WIRING CONFIGURATION *

Figure G-1 shows the general wiring needed for a dual Modbus network in a redundant system. For typicalRS-232 and RS-485 cable connections, refer to Appendix F.

FIGURE G-1 Redundant System Wiring Configuration

#

APPENDIX G—REDUNDANT SYTEM WIRING CONFIGURATION CG39FDI-3

May 1997G-2

MODBUS_SSERIAL_ANALYZER

EN

ID

ADDR

START

NUM

DATA

ENG_LO

ENG_HI

- FALSE

- FALSE

- ' '

Example viewing the array:

'01 03 00 03 00 01 AC 45'

RCVD_MESSAGES[1]'01 01 00 10 00 01 34 65'

RCVD_MESSAGES[2]'02 01 00 20 00 01 EF 28'

RCVD_MESSAGES[3]

TRUE

EN_SERIAL_ANAL - 2

ID1 -

-

-

6 -

RCVD_MESSAGES -

-

-

NDR

ERROR

E_CODE

CG39FDI-3 APPENDIX H-USING MODBUS_S AS A SERIAL ANALYZER

May 1997 H-1

H.0 APPENDIX H — USING MODBUS_S AS A SERIAL ANALYZER *

The following describes how to configure a Modbus Slave (MODBUS_S) block to be used as a serialprotocol analyzer. Using the block in this way permits you to view messages coming into the control module(i.e. ACM/CCM) in both Modbus master and slave applications. Refer to Figure H-1 as an example ofsetting up a serial analyzer. Position the Serial Analyzer block on the configuration sheet so that it is the firstModbus function block to execute. The incoming Modbus messages are placed into a string array one byte ata time in hex ASCII format.

FIGURE H-1 MODBUS_S Block Used as a Serial Analyzer

H.1 SERIAL ANALYZER INPUTS

EN Data Type: BOOL

When the ENable input is TRUE, the function block looks for incoming messages. If a message isfound and the MODBUS ADDR matches, the data is converted to hex ASCII format. As much of themessage as possible is placed into one DATA array element. When EN is FALSE, the array is notoverwritten. When the EN input transitions from FALSE to TRUE, the array connected to DATAinput is cleared.

APPENDIX H-USING MODBUS_S AS A SERIAL ANALYZER CG39FDI-3

May 1997H-2

ID Data Type: INT

A valid ID input must be configured for each MODBUS_S function block to execute. The IDoriginates from a SERIAL connect block, which can be used for multiple MODBUS_S blocks in acontrol module (ACM/CCM).

ADDR Data Type: INT

If not configured, all messages are received and placed into the DATA array. If a specific Modbusslave address is configured, only messages to that slave address are placed into the DATA array.

START Leaving this input unconfigured selects the Serial Analyzer Mode.

NUM Data Type: INT

This input defines the number of array elements to use for placing received messages.

DATA Data Type: Single dimension STRING array is used for Serial Analyzer Mode

Received messages that match the slave address definition are placed into the DATA array. Each newmessage is placed as the next element of the array and the following array element is emptied (set to ‘’). When the end of the array is reached, new messages overwrite old ones starting at the first arrayelement. Each byte in a Modbus message takes 3 characters in the string array element. This meansthe largest message would be 84 bytes captured without a Max_Size_Exceeded error, assuming a254 byte string size for the array. If the message cannot fit into the array element, as many bytes aspossible are placed into the array element and the following array element will have the error string‘Max_Size_Exceeded’ placed into it.

ENG_LO Not used in this application; leave it unconnected.

ENG_HI Not used in this application; leave it unconnected.

H.2 SERIAL ANALYZER OUTPUTS

NDR Data Type: BOOL

When a message is received through the serial port for the configured function block, the BOOLoutput toggles from FALSE to TRUE and then back to FALSE the next scan. This input staysTRUE if messages are being received every scan.

CG39FDI-3 APPENDIX H-USING MODBUS_S AS A SERIAL ANALYZER

May 1997 H-3


An error condition received by this block will cause the output to go TRUE for one control modulescan.

E_CODE Data Type: STRING

This output provides a STRING description of an error condition. A value of 0 at the outputindicates no errors. A Max_Size_Exceeded error will be displayed if the received message cannot fitinto the array element. Other error strings are described in Appendix C.

H.3 SERIAL ANALYZER SOFT LIST PARAMETERS

Soft list parameters are ignored when in the Serial Analyzer mode.

#

Documents

CG39FDI-3r2: MODBUS Slave FB Library - Siemens Modbus Slave FB Library contains the Modbus Slave (MODBUS_S) function block, which allows the control module to act as a Modbus slave