Modbus Communications

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Modbus Communications
2
Customer Protocol Needs

• Connection to multiple vendor devices
• Support for multiple protocols
• Easy system expansion and migration paths
• Between PLC manufacturers
• Proven off-the-shelf solutions
• Custom solutions no longer acceptable

Our objective is to provide these solutions for
Rockwell Automation hardware platforms
3
Presentation Overview

• Modbus Network Model
• Relate it to Rockwell model
• Three Modbus Implementations
• Technical overview
• Product solutions
• Applications
• Tools
• Applications

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RA Model
Rockwell Automation
Ethernet
ControlNet
DeviceNet
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Modbus Network Model
Rockwell Automation
Modbus
Ethernet Modbus
Ethernet
System
ControlNet
PLC I/O
DeviceNet
Device
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Rockwell Automation
Modbus
7
ProSoft Solutions
Modbus
Ethernet Modbus
Our objective is to give Rockwell Automation
customers connectivity to the Modbus Network Model
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Modbus Overview

• History
• Developed in late 70s
• Open specification from the beginning
• Simple to use and troubleshoot
• Result of open protocol
• Many device manufacturers support Modbus
• Adopted in many SCADA applications

Modbus
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Modbus Technical Overview

• Type of protocol
• Master - Slave
• Transaction
• Simple packet

Modbus
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Modbus Technical Overview

• Physical Connection
• Point to Point
• RS-232
• Multidrop
• RS-422 and RS-485
• Hardware Implementation
• Standard UART technology
• Communications
• Baud rates 1200 to 38400

Modbus
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Modbus Solutions
Modbus
Protocol Modules
SCANPort
FLEX Adapter
5/03 RTU
Modbus
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Protocol Modules - PLC/SLC

• Modbus Master Slave
• Two Comm Ports
• RS-232, 422, 485
• Jumper Selectable
• Backplane Transfer
• Fast Data Update times
• Simple ladder logic
• Sample with product
• Configuration stored in Data Table

3150 for SLC ( 5/02 )
3100 for PLC
Modbus
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Modbus Master Application
MCM Module operating as Master
Modbus
Modbus
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FLEX Modbus Adapter

• Supports FLEX and Integra I/O modules
• Discrete and Analog I/O
• Up to 8 modules
• Dip Switch Config.
• Pre-mapped Modbus Table
• Optimized
• Master Broadcast Command Support

Modbus
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Application Examples

• A-B FLEX I/O Connection to Modbus Master

DCS System
PLC System
Soft Control
Modbus
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RTU-5/03 The SCADA Processor

• SLC processors
• 8K and 16K versions
• Very unique product
• SLC 5/03 w/ Modbus Slave on front port
• Autoswitch between Modbus and DF1
• Regular program tools

Modbus
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RTU-5/03 The SCADA Processor

• No Ladder Logic required for Modbus
• Only simple data table configuration required
• Easy migration from existing SLC programs
• N100 File for Modbus configuration

Modbus
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RTU 5/03 Applications

• Any SCADA project where Modbus specified
• SLC Family Ideal RTU
• Flexible I/O
• Communications
• Local Control
• Industries
• Water
• Oil Gas
• Power Utility
• Mining

Host System SCADA package
Radio Lease Line Satellite w/ Modbus
ProSoft RTU-5/03 processors at remote locations
Modbus
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MCM Configuration Utility
Modbus
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Modbus Plus

• History
• Developed in late 80s
• Modicons PLC Level protocol
• Proprietary specification
• Technology license required
• Purchase chipset from Modicon
• Current status
• High degree to customer loyalty
• Reasonable device manufacturer support
• ModConnect program

Modbus Plus
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Modbus Plus Technical Overview

• Transaction type
• Peer to Peer
• Communications
• Baud Rate 1 Megabaud
• Modbus packet embedded inside HDLC packet
• Easy Implementation
• Application code handed Modbus packet
• Chipset strips off network layer

Modbus Plus
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Modbus Plus Technical Overview

• Physical
• Multidrop up to 64 nodes per line
• Isolated RS-485 (Two wire plus shield)
• Bridge together to 5 levels

Modbus Plus
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Modbus Plus Solutions
Modbus Plus
PLC/SLC Modules
SCANPort
Modbus Plus
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SCANport Modules

• A-B Drives to Foreign Protocols
• Modbus
• Modbus Plus
• Access all parameters
• Includes Data Link support
• Dip Switch Configuration
• Pre-Mapped Modbus Table
• Familiar to Modicon Users

Modbus
Modbus Plus
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SCANport Applications
Ethernet Modbus
Bridge
Connect Rockwell SCANport devices (Drives, SMP3,
SMC Dialog Plus) to Modbus Plus
Modbus Plus
Bridge
Modbus
Modbus Plus
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Modbus Plus Modules

• Puts Modbus Plus directly onto backplane
• Fast Data Update Times
• Global Data Support
• Prioritized high speed data
• Simple ladder logic
• Shipped with product

3350 for SLC (5/02 or better)
3300 for PLC
Modbus Plus
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Modbus Plus Modules

• Configuration via Data Table
• Use standard programming tools
• Optional Windows Configuration Utility
• Easy setup and monitoring

3350 for SLC (5/02 or better)
3300 for PLC
Modbus Plus
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PLC/SLC Applications
Ethernet Modbus
Connect Rockwell PLCs and SLCs directly to Modbus
Plus network
Bridge
Modbus Plus
Bridge
Modbus
Modbus Plus
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PLC/SLC Applications
ControlNet
Connect Modbus Plus devices directly to Rockwell
PLCs and SLCs
Modbus Plus
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Modbus Plus Config Utility
Modbus Plus
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Ethernet Modbus Overview

• History
• Introduced in recent years
• Open specification published by Modicon
• Current status
• Acceptance ramping up
• Primary support by HMI and DCS manufacturers
• Available with Modicons Quantum PLC

Ethernet Modbus
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Ethernet Modbus Technical

• Based on Modbus packet
• Data portion of message is Modbus packet

Ethernet Modbus
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Ethernet Modbus Transaction
Client
Data
Transport Layer (TCP)
IP Layer
Network Access Layer
Network Access Layer
IP Layer
Transport Layer (TCP)
Port 502 Server
Data
1
2
Ethernet Modbus
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Ethernet Modbus

• Modbus Ethernet support in PLC rack
• Capabilities
• Router
• Protocol Converter
• Modbus Master
• Modbus Slave
• Side Connect to PLC as an option
• DMA Data update times

Data Transfer to PLC
3800-MNET (PLC Platform)
Ethernet Modbus
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Ethernet Modbus

• Three Modbus ports
• Master or Slave
• All Modbus modes
• Connect up to 96 devices to module
• Data concentration
• 7000 word PLC data interface
• Built in Web Server

Data Transfer to PLC
3800-MNET (PLC Platform)
Ethernet Modbus
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Application
Ethernet Modbus
Modbus
. . . . . . .
1
2
30
31
32
MNET Module
Modbus
. . . . . . .
1
2
30
31
32
Ethernet Modbus
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Applications Types

• Applications
• Device connectivity
• Inter-PLC Connectivity
• SCADA
• Industries
• Oil Gas
• Petrochemical
• Water/Waste Water
• Pulp Paper
• Power Utility
• Etc.

Modbus
Modbus Plus
Ethernet Modbus
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Pulp Paper Application
Modbus Ethernet
Modicon Processor
Operator Workstation
PanelViewOperator Terminal
Control Logix (2nd Quarter 1999)
ControlNet
Variable Speed AC Drive
I/O
Remote I/O
PLC-5 Controller
Flex I/O
Industrial Computer with SIGMA Software
Control Logix Controller
AutoMax Controller
Variable Speed Drives
Variable Speed AC Drive
SMP-3 Solid-state Overload Relay
Valve Actuators
Single Loop Controllers
Reliance Motors
Power Monitors
Paper Machine Drive System
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Substation Automation
Host connection via Radio
Modbus
Modbus
Modbus Plus
Schweitzer Labs SEL-2020
Power Meters
Power Relays
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In the Future . . . .?
Modicon Processor
Operator Workstation
PanelViewOperator Terminal
Control Logix (2nd Quarter 1999)
Ethernet
Variable Speed AC Drive
I/O
PLC-5 Controller
Flex I/O
Industrial Computer with SIGMA Software
Control Logix Controller
AutoMax Controller
Bridge
Remote I/O
Modbus
Variable Speed Drives
Variable Speed AC Drive
SMP-3 Solid-state Overload Relay
Valve Actuators
Single Loop Controllers
Reliance Motors
Power Monitors