Supervisory Control & Data Acquisition

Communication Technology

Which Network Do I Use?

Interbus S

Device Net

Echelon

Profibus

Ethernet

Seriplex

CAN

SDS

ASI

Modbus Plus

•Seriplex FAQ •CAN FAQ •Interbus S FAQ•IBS club•WorldFIP•LON works•Modbus

•Fieldbus compare•Honeywell •Control competition

Modbus

What is a Network ?

A group of devices physically connected together for the purpose of sharing information, resources and a common transmission medium.

Why do you need a network?

Control the flow of information• security, accessibility, data control

Centralize resources• save cost on local work stations and peripherals

Simplify data / software management• Backups, IS maintenance

• Share information with multiple users

Distribute tasks• reduce local need CPU power

What makes a network work ?

Computers, printers …... Network interface cards Network adapter Software drivers Network Cabling Network protocols

Master / Slave

(Similar to the teacher- student relationship)

Peer to Peer

(Similar to the workgroup concept)

Client / Server

(Similar to an automated teller transaction)

The Basic Types of Networks

Slave SlaveSlave

Master

Master / Slave Network

Central Control and Administration Central Processing of Information Polling of Stations

Peer To Peer Network

Distributed Administration Independent Processing of Information Shared Transmission Medium

Client / Server Network

Central Network Administrator Controlled Flow of Information Independent Processing of Information Shared Transmission Medium

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Layers Designedfor Data Processing

Layers Designedfor Communications

How is a network put together ?

The OSI model uses 7 layers to categorized the main elements of a basic network

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

OSI Model Layers

A Model is used to ensure Compatibility Each station utilizes the same Protocol Stack

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

OSI Model: Flow of Data

Logical Structure Data Multiplexing

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Software Layers

Hardware Layers

Hardware / Software integration

The upper five layers are implemented with software The lower two layers are implemented with hardware

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Twisted Pair/ Fiber Optics

Internet Protocol

Transmission Control

Application

CSMA - CD

OSI Model vs. Ethernet -TCP/IP

Ethernet does not incorporate all 7 layers because it’s development predated the OSI model

CDMA/CD – Carrier Sense Multiple Access with Collision Detection

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Multiple Mediums

Application

ASIC Dependent

OSI Model vs. Field Bus Model

The typical field bus only utilizes 3 layers. The functions of the other layers are either built into the ASIC chip or the application layer

ASIC - Application-Specific Integrated Circuit

What is common to all networks ?

Application message - dependent on software package• The message is created by the application package

Media Access Control• The procedure for sharing the physical medium

Logical Topology• The associations between the devices

Physical Topology• The layout of all the device connections

Transmission Mediums• The physical path used between the devices

Jacket of PVC or Teflon

Jacket made of PVC or Teflon

Various Transmission Mediums

Coaxial Cable

Twisted Pair

Optical Fiber

Wireless

Basic Physical Topologies

Bus Topology Star Topology Ring Topology Free Topology Hybrid Topology

Bus Architecture Topology

Single Channel - Broadcast oriented• More delicate to maintain signal integrity based on cable

selection, distance and drops/taps

Star Architecture Topology

Central Hub• multi-port repeater

– Loose star = lost network

• channel selecting switch

Token Ring

Ring Architecture Topology

Each device is a repeater• Loose node= broken ring

Free Topology

Devices are wired in any combination of topologies Usually requires one terminator

term

.Bus

LoopStar

X25Phone System

Hybrid Architecture Topology

Non-rooted Tree Architecture (ex.- Internet)

Network Extenders

Repeater and Hub Bridge Router Gateway

Repeater and Hub

Bridge

RouterGateway

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Physical Layer Network Extenders

Repeater or Hub• Active repeaters regenerate the signal (store and forward)

• Passive repeater amplifies the signal; adds no latency

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Data Link Layer

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Data Link Layer

Data Link Layer Network Extenders

Bridge or Level 2 Switch

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Network

Data Link LayerPhysical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Physical Medium

Network

Data Link Layer

Network Layer Network Extenders

Router or Level 3 Switch

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Application

Physical Medium

Network

Transport

Session

Presentation

Application

Datalink Layer

Application

Application Layer Network Extenders

Gateway

Logical Terminology & Topologies

Node Segment / Channel Subnet Network Domain System

Node

Bridge

Gateway

Domain A Domain B

Router

Network A

Network B

RouterSubnet

Segment

Subnet

Segment

A Node

A collection of SW objects that communicate over a network based upon a single hardware ID.

A physical device may contain one or more nodes• Example - a router

Node

Node IDParameters

Data

Segment

Node

NodeNodeNodeNodeNode

Segment / Channel

One or more nodes electrically connected to a continuous section of a transmission media

May include the trunk line, drop line, multi-port taps and other cable components.

Subnetwork (Subnet)

One or more nodes sharing a common protocol and a media access arbitration method

May contain multiple segments

Subnet

Segment

Segment

Segment

Network

Network

One or more subnets using a common network level protocol where each hardware ID is unique on the network

May contain multiple subnets

Domain

One or more networks where each network has a unique ID within the domain

May contain a variety of network types connected together with gateways and routers

Domain

GatewayNetworkRouter

Network

Network

Network

System

System

One or more Domains

Domain

Domain

Domain

Basic Media Access Control Methods

Time Division AccessPolled AccessToken AccessCarrier Sense Multiple Access

NODE #2 NODE #5NODE #12 NODE #10Token

How will they share the common media ?

Time Division Access

Utilizes a master clock Each device is assigned a slice of time

Polled Access

Utilizes one device as a master Other devices a considered slave devices The master requests information from each slave The slave responds to the request

DP

-Sla

ve

imm

edia

tere

spo

nse

Sla

ve

Mas

ter

Header Input Data Trailer

Trailer Output Data Header

Request Frame

Response Frame

Token Access

Every device is considered equal A token is used to administer access rights The token is passed logically among the devices Requests are initialized when a device possess the token

NODE #2 NODE #5NODE #12 NODE #10Token

Message

MessageMessageMessage Message

MessageToken

Token Token Token Token Token

Token

Token

Carrier Sense Multiple Access

No priority is assigned to the devices All the devices contend for access Messages are only sent if the shared media is not in use

NODE #2 NODE #5NODE #12 NODE #10

Message

MessageMessageMessage Message

Message Message

MessageMessageMessage

Message

Multiple Mediums & Physical Topologies

Application: message specifications

Various Media Access Methods: ASIC Dependent

Typical Automation Field Bus Model

The typical field bus only utilizes 3 layers. The functions of the other layers are either built into the ASIC chip or the application layer

The application layer will characterize the overall function of the field bus or the network.

Basic Types of Automation Networks

Data Network Control Network Device Bus / Field Bus Sensor / Actuator Bus

Operations Level

Management Level

System Level (Cell)

Process Level

Sensor / Actuator Level

Control Network

Data Network

Device Bus / Field Bus

Sensor/Actuator Bus

Network Levels - Typical Applications

Level 2

Level 1

Level 0.5

Level 0

Host

HMIController

Peer

IntelligentDevices

Pusbutton Sensor

Level 2: Hosts• Recipe data downloads

• Production data uploads

• Application programming and management

Level 1: Control• Peer to peer data

• HMI displays

Level 0.5: I/O• I/O racks and blocks

• Intelligent devices

– Variable frequency drives

– Process valves

– Power meters

– Complex Sensors

Level 0: Devices• Pushbuttons / Simple sensors

Network Levels - Transmission Characteristics

Level 2: Hosts• Data: blocks or files

• Frequency: seconds to minutes

• Distance: LAN / WAN / Internet

Level 1: Control• Data: words or blocks

• Frequency: 50 to 500 Milliseconds

• Distance: 300m

Level 0.5: I/O• Data: bytes or words

• Frequency: 20 to 100 Milliseconds

• Distance: 300m

Level 0: Devices• Data: bits

• Frequency: 5 to 50 Milliseconds

• Distance: 30m

Level 2

Level 1

Level 0.5

Level 0

Host

HMIController

Peer

IntelligentDevices

Pusbutton Sensor

Communication Network Levels

Data NetworkInformation Level( Level 2 )

Control NetworkWord Level( Level 1 )

Device / Field BusByte & Word Level( Level 0.5 )

Sensor/ Actuator BusBit Level( Level 0 )

Ethernet TCP/IPToken ring

Modbus PlusFIPWayDevice NetEthernet TCP/IP

Remote I/OInterbus ™Profibus DP ™DeviceNet ™ Lonworks ™Fip IO ™

Lonworks ™Seriplex ™

ASi ™

File Transfers

Data TransferProgram

DiscreteAnalogSet PointsWords

DiscreteLimited Analog

Level Network Name Information Type

* ™ is a trade mark

Automation & Control System Hierarchy

Automation and control systems can incorporate them all

Sensor / Actuator Bus

Sensor Actuator Buses are bit level oriented

Sensor / Actuator Bus

LONworks

16-100 ms64 nodes

32385500m

228 bytesHighHighLarge

SpeedNodes

DistanceMessage SizeNode CostInstalled CostPhysical Size

ASi

5ms31 nodes

31100m4 bitsLowLowSmall

Seriplex

0.7ms64 nodes

5101500m1 bitLowLowSmall

Controller Network Interface Module

PushButtons

PilotLights

ActuatorsValves

ASi power supply 24 V DC

Distribution Module

I/O Module

ASI Communication Network Master - Slave Network – polled media access method Utilizes a special 2 conductor cable for data and power Data size - 4 bits 31 maximum slave devices on the bus

PushButtons

PilotLights

ActuatorsValves

Controller / Network Interface Module24 VDC power supply

Seriplex Communication Network

Master - slave or peer to peer network type Time division media access control - 100kHz clock Special 4 conductor cable - clock, power, data, common Clock pulse number equals address

Device / Field Bus

Device Buses incorporate intelligent devices

Device / Field Bus

Profibus-DP

10 ms32 nodes

321200m

246 bytesMedium

HighLarge

SpeedNodesMax nodesDistanceMessage SizeNode CostInstalled CostPhysical Size

Interbus S

4 ms256 nodes

N/A13km

MediumLow

Medium

Device Net(CAN)

10-52 ms64 nodes

64250m

8 bytesMedium

HighMedium

T/C, RTD, Servo, Barcode, RF Tag

Quantum Controller Compact 984 I/O Modules

PC based Operator Control Station

NOA 611 Interface

Third Party Products

Terminal I/O Modules

BDEA 202Interface

Interbus Network

Many third party suppliers Large physical topology 12km Price competitive

Loss of device or connection disables complete system

InterBus-S Strong points

• High performance I/O exchanges, deterministic protocol

– Approx. 7 ms for 128 devices with 32 I/O (2048 input bits, 2048 output bits)

– Built-in reflex functions

• Standardized profiles , interoperability, unique installation tool : CMD tool, product catalogue

• Different physical layers (loop sensor )

• Activation / deactivation segment

• Fault localization

Weak points• Low performance message

handling– Adapted to parameter

setting only. 1 to 8 words per device and per bus cycle

– No slave to slave communication

• No diffusion (variable or message handling)

• One level of priority for cyclic variables

• No downgrade mode– The bus stops in the event

of a fault on the device– When the bus restarts,

the following devices cannot be accessed

• DIN standard– Similar to Phoenix Contact

strategy (components, policies, etc)

ActuatorsValves

Controller / Network Interface

24 VDC power supply

PushButtons

I/O Module Drives

MOD IC ON

I/O Module

DeviceNet Communication Network

Limited physical topology 500m

Terminal I/O Modules

up to 1200m distance

Direct connection to third party products

Controller / NetworkInterface Module

Computer / NetworkInterface Module

Controller / NetworkInterface Module

ProfiBus DP Network

Large physical topology 24km (fiber)

Difficult to configure and maintain; needs multiple software pieces

MODIC ON MODIC ON

Lighting Assemblies Switch

I/O Modules

Photo Sensor

ProgrammableController

Computer

LONWorks Communication Network

Free topology and highly flexible

Large number of nodes 32000/domain

Slower cycle times

Control Networks

Control Networks require critical performance

Control Networks

SpeedNodesDistanceMessage SizeNode CostInstalled CostPhysical Size

Modbus Plus20k reg/sec

6413km

100 registersMedium

LowMedium

FIPWAY10-80 ms

321000m

128 bytesMedium

HighLarge

Modbus Plus FIPWAY

ModConnect

984 ControllerQuantum ControllerCompact 984 Controller

Operator Control Station

Terminal I/O Modules

Third PartyProducts

Modbus Plus Network

Modbus Plus excellent performance Predictable performance As fast as hardwired I/O

• Typical token rotation time of 2 milliseconds per node

• Maximum network throughput of 20,000 registers/Sec

0

2000

4000

6000

8000

10000

2 4 10 20 30

Network Throughput

Nodes

Reg/Sec per Node

Data Networks

Data Networks extend the information capabilities

Data Networks

NodesMax NodesDistanceMessage SizeNode CostInstalled CostPhysical Size

Ethernet

8 - 24 nodes/hubUnlimited

100 m (node to hub)Unlimited

LowDepends on Extent of Network

World Wide

Ethernet Backbone

Hub

Laptop Hub

QuantumEthernet

Offices

PlantFloor

QuantumEthernet

10Base-T

10Base-T

Ethernet Data Network

Important Application Information

Number of nodes (I/O points) required. Distance between I/O points. Overall network distance. Data throughput required. Preferred PLC Controllers being utilized Bit level traffic quantity Word level traffic quantity Preferred Media (coax, fiber, twisted pair,…..) Maintenance preferences Greenfield installation Installed base Preferred vender list