Automation Direct T1K-MODBUS-M User Manual

Terminator I/O

MODBUS

Base Controller

User Manual

Manual Number T1K–MODBUS–M

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1

i

Table of Contents

Chapter 1: Introduction

Manual Overview 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Purpose of this Manual 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Supplemental Manuals 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Who Should Read this Manual 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Technical Support 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Manual Layout 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Symbols Used 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction to MODBUS 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Terminator I/O System 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T1K–MODBUS Base Controller 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MODBUS Base Controller Features 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 2: T1K–MODBUS Base Controller Specifications

T1K–MODBUS Base Controller Specifications 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Status Indicators 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting the DIP Switches 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIP Switch Settings 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting the Rotary Address Switches 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Converting HEX Addresses to Decimal 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MODBUS Port Pin–out and Wiring 2–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RJ12 Serial Port Pin–out and Wiring 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using D2–DSCBL to Connect PC to RJ–12 Serial Port 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 3: MODBUS RTU Functions and Addressing Modes

MODBUS RTU Function Codes 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MODBUS Function Codes Supported 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DirectLogic Addressing Mode 3–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using the T1K–MODBUS with a DirectLogic PLC Modbus Master 3–3. . . . . . . . . . . . . . . . . . . . . . .

584/984 Addressing Mode 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using the T1K–MODBUS with a 584 / 984 MODBUS Master 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . .

ii

Table of Contents

Chapter 4: Using the T1K–MODBUS Setup Tool

Configuring the T1K–MODBUS Port 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installing the Setup Tool 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Launching the Setup Tool 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Select the PC Comm Port 4–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Configure the MODBUS Port 4–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix A: I/O Module Hot Swap

T1K–MODBUS I/O Module Hot Swap Feature A–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Check External 24VDC Wiring Before Hot Swapping! A–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Hot Swap: I/O Module Replacement A–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Outputs Enable / Disable Switch A–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix B: Analog Output Module Configuration

Analog Output Module Control Byte B–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

Manual Revisions

If you contact us in reference to this manual, be sure to include the revision number.

Title: Terminator I/O MODBUS Base Controller User Manual
Manual Number: T1K–MODBUS–M

Edition Date Description of Changes

1st Edition 08/01 Original Issue

i

Introduction

In This Chapter. . . .

— Manual Overview
— Introduction to MODBUS
— Terminator I/O System
— T1K–MODBUS Base Controller

1

1

1–2

Introduction

Manual Overview

The Purpose of
this Manual

Introduction

Supplemental
Manuals

Who Should Read
this Manual

Technical Support

This manual describes the installation and
operation of the Terminator I/O MODBUS
Base Controller (T1K–MODBUS).

The following manuals are essential to the proper use of your Terminator I/O
MODBUS Base Controller.

• Terminator Installation and I/O Manual part number T1K–INST–M
This manual contains very important information, including a complete

I/O Module Memory Map. The Memory Map is crucial in designing and
implementing a Terminator I/O system.

• The PLC User Manual (if PLC is used as master).

• The MODBUS Master manual (if other than PLC is used as master).

If you have a working knowledge of MODBUS networks, and the PLC or PC which
you are using, this manual will help you configure and install your T1K–MODBUS
Base Controller.

We strive to make our manuals the best in the industry and rely on your feedback in
reaching our goal. If you cannot find the solution to your particular application, or, if
for any reason you need additional technical assistance, please call us at

770–844–4200.

Installation and

Safety Guidelines

Our technical support team is glad to work with you in answering your questions.
They are available weekdays from 9:00 a.m. to 6:00 p.m. Eastern Time. We also
encourage you to visit our website where you can find technical and nontechnical
information about our products and our company.

www.automationdirect.com

Introduction

1–3

Manual Layout

Chapter Title What’s covered

1
2

MODBUS RTU Functions

3

and Addressing Modes

Using T1K–MODBUS

4

Appendices

Appendix Title What’s covered

The contents of this user manual are as follows:

Introduction

T1K–MODBUS
Specifications

Setup Tool

Additional reference information for the T1K–MODBUS is available in the following
appendices.

introduces MODBUS and describes both the Terminator
I/O System and the T1K–MODBUS Base Controller

provides module specifications, dip switch settings, port
pin–outs and wiring information.

provides MODBUS RTU functions supported and use
with DirectLogic PLCs, or MODBUS 584/984 modes.

explains how to configure the MODBUS port using the
Setup Tool.

Introduction

A

Analog Output Module

B

Symbols Used

I/O Module

Hot Swap

Configuration

The “note pad” icon in the left–hand margin indicates a special note.

The “exclamation mark” icon in the left-hand margin indicates a warning or caution.
These are very important because the information may help you prevent serious
personal injury or equipment damage.

The “light bulb” icon in the left-hand margin indicates a tip or shortcut.

explains the T1K–MODBUS I/O module Hot Swap feature
and the Enable/Disable Outputs switch.

uses a memory map to explain how to configure an analog
output module.

Safety Guidelines

Installation and

1–4

Introduction to MODBUS

Introduction

Introduction

MODBUS RTU (Remote Terminal Unit) Protocol is a messaging structure used to
establish master–slave communications between intelligent devices. When a
MODBUS master sends a message to a MODBUS slave, the message contains the
address of the slave, the function, the data and a check sum. The slave’s response
message contains fields confirming the master’s request, any data requested and
an error–checking field.

A typical MODBUS RTU frame consists of the following fields:

ADDRESS FUNCTION DATA CHECKSUM

The address field of a message contains 8 bits. Valid slave addresses are in the
range of 0– 247 decimal. The individual slave devices are set in the range of 1 – 247
decimal (address 0 is the broadcast to all slaves address). The master specifies a
slave by placing the slave address in the address field of the message. When the
slave responds, it places its own address in the address field to identify to the master
which slave is responding.

Installation and

Safety Guidelines

The function code field of a message contains 8 bits. V alid function codes are in the
range of 1 – 255 decimal. The function code instructs the slave what kind of action to
take. Some examples are to read the status of a group of discrete inputs; to read the
data in a group of registers; to write to an output coil or a group of registers; or to read
the diagnostic status of a slave.
When a slave responds to the master , it uses the function code field to indicate either
a normal response or that some type of error has occurred. For a normal response,
the slave echoes the original function code. In an error condition, the slave echoes
the original function code with its MSB set to a logic 1.

The data field is constructed using sets of two hexadecimal digits in the range of 00
to FF. According to the network’s serial transmission mode, these digits can be made
of a pair of ASCII characters or from one RTU character.
The data field also contains additional information that the slave uses to execute the
action defined by the function code. This can include internal addresses, quantity of
items to be handled, etc.
The data field of a response from a slave to a master contains the data requested if
no error occurs. If an error occurs, the field contains an exception code that the
master uses to determine the next action to be taken. The data field can be
nonexistent in certain types of messages.

The checksum field is used for error checking. Standard MODBUS serial networks
use two types of error checking.
Parity checking (even or odd) totals the number of logical 1 bits in the data field and
sets the parity bit to a 0 or 1 representing an odd or even total of logical 1 bits. Cyclical
Redundancy Check (CRC) checks the entire message and is applied regardless of
any parity check method used. The CRC field consists of two bytes, creating a 16 bit
binary value. The CRC is calculated in the transmitting device and is recalculated
and compared by the receiving device.
Both the character check and the message frame check are generated in the master
device and applied to the message before transmission. The slave device checks
each character and the entire message frame during receipt.

Terminator I/O System

MODBUS

Terminator I/O is a modular system which combines the functions of terminal blocks
and I/O modules for distributed I/O. Each Terminator I/O system has the following
components: a Power Supply, a Base Controller, and one or more I/O Modules and
I/O bases.

1–5

Introduction

Introduction

Power Supply

Base
Controller

I/O Module

I/O Modules

Safety Guidelines

Installation and

I/O Base