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Practical Troubleshooting & Problem Solving of Modbus Protocols

Date post: 06-Dec-2014
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This manual focuses on the main issues of troubleshooting the industrial data communications network of today, enabling you to walk onto your plant or facility to troubleshoot and fix problems as quickly as possible. The focus is on the Modbus suite of protocols and their associated standards. MORE INFORMATION: http://www.idc-online.com/content/practical-troubleshooting-and-problem-solving-modbus-protocols-196?id=84
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Technology Training that works Practical Troubleshooting & Problem Solving of Modbus Protocols
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Page 1: Practical Troubleshooting & Problem Solving of Modbus Protocols

Technology Training that works

Practical Troubleshooting & Problem Solving of Modbus Protocols

Page 2: Practical Troubleshooting & Problem Solving of Modbus Protocols

Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare

Objectives

• Describe the modern instrumentation and control system

• List the main industrial communications systems

• Describe the essential components of industrial communications systems

Page 3: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Introduction

• Data communications - transfer of information from one point to another

• Modern instrumentation - Transfer of digital data

• Communications system A transmitter to send information, a receiver to accept it, and a link (the medium) between the two

• Protocols - Rules governing the communication

Page 4: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Modern instrumentation and control systems

• Purpose of an instrumentation and control system :

Control of the processes and alarms

Control of sequencing, interlocking and alarms

An operator interface for display and control

Management information • Devices having significant impact

on control of plants :

Distributed Control Systems (DCSs)

Programmable Logic Controllers (PLCs)

SCADA (Supervisory Control And Data Acquisition)

Smart Instruments

Page 5: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Smart Instrumentation systems

Graphical representation of data communication

Page 6: Practical Troubleshooting & Problem Solving of Modbus Protocols

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OSI Model

• Developed by the International Organization for Standardization

• Universal framework for building communications systems

• 7-layer model

• Missing the 8th (‘user’) layer

Page 7: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Open Systems Interconnection

Page 8: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Protocols

• Rules for transmission of data • Asynchronous (byte oriented) or synchronous (packet

oriented) • Information can include:

– Sync byte(s)– Function code– Destination address– Source address– Data– Checksum (BCC, CRC, etc)

Page 9: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Basic structure of an information frame

SYNCHRONIZING BYTE(s) used to synchronize the receiver

DESTINATION ADDRESS where the packet is going

SOURCE ADDRESS where the packet is coming from

DATA the information contained in the packet

ERROR DETECTION (CHRECKSUM) BYTE(s) the result of the error detection calculation

Page 10: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Standards within a communications system

• Codes (Hex, ASCII, etc)

• Physical layer implementations (RS-232, RS-485 etc)

• Protocols (Modbus, DF-1, etc)

• Networks (Profibus, Hart, AS-i, Data Highway Plus, Ethernet, etc)

A typical serial data communications link

Page 11: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Typical two-wire multi-drop RS-485 network

Page 12: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Standards

• Modbus :

Format of Modbus Serial message frame

• TCP/IP :

The Process/Application layer

The Services or Host-to-host layer

Internet layer

• Ethernet : Non-deterministic method, simple and low cost

Page 13: Practical Troubleshooting & Problem Solving of Modbus Protocols

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Radio modem configuration

Page 14: Practical Troubleshooting & Problem Solving of Modbus Protocols

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DO YOU WANT TO KNOW MORE?

If you are interested in further training or information, please visit:

http://idc-online.com/slideshare


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