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Ethernet I/O

Brad S. Carlberg, P.E.

Jim McConahay

Co-Presenter: Brad S. Carlberg

Brad S. Carlberg, P.E. is a Consulting Engineer in Richland, Washington. He is a Registered Professional Control Systems Engineer in the states of Alabama and Washington with over twenty-five years experience in industrial automation and Process Control Engineering. Specifically he has experience with Distributed Control Systems and Programmable Logic Controllers combining extensive experience with both Hardware and Software Design, Programming, Implementation and Startup. Brad received his Bachelor of Science in Mechanical Engineering from Washington State University in Pullman, Washington in 1984. Brad is a Senior Member of ISA who has been a conference program committee member since 1997.

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BSCEngineering

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Co-Presenter: Jim McConahay

Jim McConahay, P.E. is an ISA member and holds a BSEE and MBA from Cal Poly University, Pomona California. Has 30+ years design and installation experience in Production and Automation equipment. Jim is a Sr. Field Application Engineer for Moore Industries-International, Inc. concentrating on process control instruments, SCADA, SIS (Safety Instrumented Systems), fieldbus, data concentrators and communications links.

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AgendaPhysical Layers of Ethernet

Protocol Medley

Migration From Cabinet to the Plant Floor

Enhanced Features of Ethernet I/O

Architecture Considerations

Security

Examples of Ethernet Communications

Agenda

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Application

Presentation

Session

Transport

Network

Data Link

Physical

OSI (Open Systems Interconnect) Model

“Ethernet” IEEE 802.3x only applies here

UTP, STP, Fiber, Coax, etc.10/100/1000/10G speeds

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6

5

4

3

2

1

OSI Model

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MODBUS, OPC, HTTP, Etc.

TCP

IP

Ethernet

Ethernet

Protocols run on top of Ethernet

Addressing and Handshaking Protocols

UTP, STP, Fiber, Coax, etc.

What “language” are you talking??Protocol

Presentation

Session

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6

5

4

3

2

1

OSI Model

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Ensure that your Ethernet I/O supports open standards for connectivity: OPC, MODBUS/TCP, Ethernet/IP, HTTP, HSE etc.

HMI, PC, DCS, PLC

HTTP

MODBUS/TCPEthernet/IP

FF HSECIP

OPC

Open Standards

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Ethernet vs. Twisted Pair

HMI, PC, DCS, PLC

SpeedMultiple Protocols over same cable

Plant wiring infrastructureNon-Proprietary hardware available (lower cost)

Switch advancements have improved determinismPower over Ethernet

Communications Media

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What if the protocols don’t match? Is there a solution?

HMI, PC, DCS,PLC

Gateway(Protocol Converter)

Ethernet to EthernetEthernet to Serial

Wireless to Serial/Ethernet

Protocol Gateway

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Protocol Converters and Gateways

• The term “gateway” has many meanings. One common definition is a protocol converter.

• Sometimes host and legacy systems can only communicate via one particular protocol. Or, instruments may support one protocol but not the one that the host system supports. Gateways can be very effective solutions that connect these two devices. Since Ethernet is “open” gateways are becoming more and more common.

• Sometimes people refer to “drivers” as gateways. A driver is essentially a protocol or language translator.

Protocol Gateway

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Simplified Gateway Example

HARTMaster

MODBUSSlave

mapping

HART Data Map MODBUS Data Map

68.6 68.6

HART Device is polled

Internal Mapping Takes Place

MODBUS Data Map

MODBUS Mastergets new data

Gateway

GatewayInternal Mem.

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Moving from the Cabinet to the Field

• Temperature Considerations 55C vs. 85C operating Temp’s.

• Channel-to-channel, and input-to-output signal isolation eliminates unpredictable ground loops

• RFI/EMI protection protects against plant noise

• Accuracy, long term stability, and Input/output resolution of transmitters

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Common I/O Multiplexer

A/D Converter mP

Signal Inputs/Outputs

Signal Input

Signal Input

Signal Input

Signal Input

A/D A/D A/D A/D

mP mP mP mP

Transmitter Like Design-isolation-flexibility of input type

Typical I/O Card Design-single point of failure-isolation

Enhanced I/O Design

Isolated Channels

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Power and Flexibility of PLC’s

Plant Floor “Industrialized” Ethernet I/O

Resolution, Accuracy, and Spec’s of Field

Transmitters(Cabinet Mounted)

(Field Mounted)

Isolated Channels

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“Hardened” Plant Floor Switches

• High Temp -40 to 85C vs. commercial ~45C• High Vibration Tolerance• RFI/EMI Rejection• Surge Protection• Dual Power Supply Options for UPS Systems

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Switch Features for the Plant Floor

• QoS (Quality of Service) -Packet Prioritization• SNMP (Simple Network Management Protocol)• SMTP Client (Emails about network warnings/breaks)• MAC Layer Filtering• IP Layer Filtering

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Programming should be easy and intuitive; i.e. web based

Set-Ups

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Do you need more than I/O gathering?

Ethernet I/O systems are smarter and more powerful than ever.

Many times PLC’s are used to perform simple control, math and logic functions.

Questions to ask your Ethernet I/O vendor

1. Does your Ethernet I/O have the ability to perform control and math?

2. Is the control programming language proprietary?

3. …

More…

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Is the programming language 61131-3 compliant?

Function Block Diagram (FBD) Example

Compliant Language

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Know your design needs before choosing your Ethernet I/O system

1. Peer-to-Host—Star Topology; Bus Topology

2. Peer-to-Peer

3. Hybrid—Peer-to-peer and Peer-to-Host

4. Wireless/Fiber/Copper

Topology

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Dispersed Monitoring & Control Devices

Ethernet I/O System

Ethernet I/O System

Ethernet I/O System

Ethernet I/O System

Additional NET Concentrator System Stations or Uplink to

Other Hubs or SwitchesEthernet Switch or Hub

TemperaturePressure

Level

DirectTransmitter Temperature

Sensors

RTDThermocouple

Analog Valve

On/OffProportional

Positioners

Contact ClosureRelay

On/OffDevices

DCS, PLC or PC with HMI/SCADA

(with NET Concentrator System OPC

Server)

Peer-to-Host System

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(cost savings with traditional I/O cards)

Ethernet/Fiber Network

Ethernet I/O System Ethernet I/O SystemPAIR 1

Ethernet I/O System

Ethernet I/O SystemPAIR 2

Ethernet I/O System Ethernet I/O SystemPAIR 3

Peer-to-Peer System

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Wireless Peer-to-Peer/Host Systems900Mhz or 2.4Ghz – License Free or Licensed

Ethernet I/O System

Ethernet I/O SystemPAIR 1

Ethernet I/OSystem

Ethernet I/O SystemPAIR 2

Add Wireless…

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Security Concerns

Firewalls

NAT Routers

Virus Protection

Physical Security (personnel and Internet Connection)

“Line speed” packet encryption systems

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Network Architecture Considerations- “Connected”

Front Office Network

Process Control Network

Router/FirewallMost Convenientbut PotentiallyVulnerable

Outside InternetConnectionsTypical

VPN

Networking

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Network Architecture Considerations- “Disconnected”

Front Office Network

Process Control Network

No Physical ConnectionSafer butInconvenient

Outside InternetConnectionsTypical

VPN

Networking

Case Study #1One communication loop, multiple bus

Problem:• PAC – Programmable Automation Controller

• Ethernet card in PAC backplane – Ethernet TCP/IP

• HMI• Ethernet IP and Ethernet TCP/IP

• Flow, valves, level sensors / FF• FF FIM; H1 to HSE link – Ethernet IP (not TCP/IP)

• Ethernet protocol conflict between FIM and PAC

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Solution:• Add MODBUS TCP to Ethernet IP Protocol Converter

– Two way FF protocol conversion with PAC

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Case Study #1One communication loop, two bus

ProtocolConverter

ManagedEthernetSwitch

ProgrammableAutomationController

(PAC)

FoundationFieldbusInterfaceModule

FIMLocalHMI

Display

FT

PT

LT

FT

PT

LT

FOUNDATION FieldbusTransmitters

FOUNDATION Fieldbus H1 Modbus TCP

Ethernet IP

Ethernet IP

ConvertsModbus TCPto Ethernet IP

• Optimized equipment for each part of the system

• Used protocol converter to make compatible– Lowest cost item in the system– Far less cost than compromise performance of a single vendor

solution

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Case Study #1One communication loop, two bus

Case Study #2Remote ESD for Oil Platform in Gulf

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Problem:• Maintenance Boat and Oil Rig Platform pipeline repairs

• Repairs involve heavy equipment above seafloor pipelines

• If accident event, need system to shut down Production• ESD (Emergency Shutdown Device)• Automatic• Reliable• Two-way verification of link

• Off shore• Portable, distance >100 km• Beyond radio links

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Case Study #2Remote ESD for Oil Platform in Gulf

Considerations:• No hard line communication links• No ESD = No Drilling ($$$)• Is existing Emails, Internet and VoIP to shore facilities

– Satellite link is reliable on platform– Satellite link is reliable on Maintenance ship

• Maintenance ship is very mobile– Easy installation– Transferrable to new ship– Simple, intuitive to operate

Solution:• Data concentrator on Maintenance boat

– Ethernet Communications module– Discrete input/output module– Packaging with switch plus display lamp tree

• Data concentrator of Oil Platform– Ethernet Communications module– Discrete input/output module– Packaging with switch, klaxon, plus display lamp tree – Connection to control panel

• Expansion– Add SCADA to ESD at negligible cost

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Case Study #2Remote ESD for Oil Platform in Gulf

Things at the surface can drop onto sea floor pipelines

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Case Study #2Remote ESD for Oil Platform in Gulf

• Success– Operational upon initial installation, continuous operation– Simple to operate, intuitive.– Reliable. Now hard-wired to control panel circuits.– Satellite signal limited by extreme weather.

• Expansion– Can add I/O modules for telemetry on both ends of links;

negligible cost.

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Case Study #2Remote ESD for Oil Platform in Gulf

• Problem:

Expansion, low budget, needs more 4-20mA channels– Requires more 4-20mA channels now– No budget to replace existing 4-20mA lengthy cable run– Will require still more channels later– Discrete contact requirement arising

• Ethernet cable upgrade– Available in the future, not now– Does not want to waste investment in temporary data

concentrator when Ethernet cable becomes available in the future

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Case Study #3Expansion of 4-20mA loops

• Solution• Data Concentrator

– MODBUS RTU communications at module each site– AIM each output; AOM each output– DIM each discrete input; ROM each discrete output– Increase number of I/O modules, as desired– Increase pairs of data concentrators

• Use existing twisted pair cable– Use one twisted pair to carry ‘all’ channels between data

concentrators

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Case Study #3Expansion of 4-20 loops

• Data Concentrator on a Peer-to-Peer network– Originally MODBUS Communications Link– Currently Ethernet Communications Link

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Case Study #3Expansion of 4-20mA loops

Success• Use data concentrators to collect all 4-20mA loops and

convert to digital communications.– Increased number of analog channels, and also easily adds

discrete channels– Only one twisted pair required– Recreate signal at distant site with no degrading of analog signal

(since communication is digital)

• Low cost Ethernet upgrade– Swap only the MIM for an EIM communications module– All other modules are same

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Case Study #3Expansion of 4-20mA loops

Problem:• Multiple tasks, need to optimize

– Tank farm, Wireless HART; multiple sensors, cable expenses– Closed loop room; add sensors, valves plus data concentrator– Host control room—long distance communication link

• Different communications media and protocol– Wireless Hart; radio– Data concentrator; analog/discrete I/O; programming– MODBUS

• Need protocol converters– Wireless Hart to MODBUS RTU slave– MODBUS RTU master; control loop; MODBUS TCP slave

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Case Study #4Wireless HART, MODBUS RTU & TCP/IP

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Case Study #4Wireless HART, MODBUS RTU & TCP/IP

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“Our View” - Market Trend with Ethernet

1. MODBUS/TCP- MODBUS packets encapsulated in TCP/IP framesReason: Everyone knows MODBUS, open protocol,and already supported worldwide

2. Ethernet/IP- “Industrial Protocol”, Rockwell released to ODVA(Open DeviceNet Vendor Association)Reason: Open, supports common publisher/subscribermethod of comm., section of protocol already supportedin open DeviceNet. Uses CIP (Common Industrial Protocol)for real time control.

3. OPC-OLE for Process Control. Uses Microsoft’s COM/DCOM/.NET standards for open comm. Reason: OPC can run over any physical medium and is anopen, free of charge protocol that both hardware vendorsand software vendors have access to. Many supporteddevelopment tools. Strong backing by OPC Foundation.

Summary

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Market Trend with Ethernet Cont’d

4. HSE- High Speed Ethernet Foundation Fieldbus protocolover Ethernet. Reason: Open protocol, and large organized supportbase by Foundation Fieldbus vendors and FF org.

5. Profinet- Profibus Trade Organization’s answer to open communications. It is NOT Profibus over Ethernet!!!Reason: Strong backing by PTO. Can use 802.3 layerbut not restricted to this layer. Can run over modems, WAN’s, VPN’s, as long as it uses TCP/IP addressing.

6. CIP- Common Industrial Protocol is being promoted byODVA (Open Device Vendors Association). Uses a Producerconsumer network philosophy for real time control applications.

Summary

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Thank You!

BSCEngineering

Questions?