Programmable Logic Controllers PLC’s An Overview, Use in HVAC and Web Technologies By Sleepy...

PProgrammable rogrammable LLogic ogic CControllersontrollers

PLC’sPLC’s

An Overview, Use in HVAC and Web An Overview, Use in HVAC and Web TechnologiesTechnologies

By Sleepy WombatBy Sleepy Wombat

OverviewOverview

What is a PLC ?What is a PLC ?

HistoryHistory

Overview of TechnologyOverview of Technology

PLC Configuration and SelectionPLC Configuration and Selection

Programming PLC’sProgramming PLC’s

PLC’s in HVACPLC’s in HVAC

Web TechnologiesWeb Technologies

What is a PLC ?What is a PLC ?PLC (Programmable Logic Controller)PLC (Programmable Logic Controller)

A PLC works by looking at its inputs A PLC works by looking at its inputs and depending on their state, and the and depending on their state, and the user entered program, turns on/off user entered program, turns on/off outputs.outputs.

A PLC can be thought of as: A PLC can be thought of as: Industrial ComputersIndustrial Computers with specially with specially

designed architecture in both their designed architecture in both their central units (the PLC itself) and their central units (the PLC itself) and their interfacing circuitry to field devices interfacing circuitry to field devices (input / output connections to the real (input / output connections to the real world).world).

History 1/4History 1/4

Early control systems consisted of huge control boards Early control systems consisted of huge control boards consisting of hundreds to thousands of electromechanical consisting of hundreds to thousands of electromechanical relays.relays.

An Engineer would design the system logic.An Engineer would design the system logic.

Electricians would receive a schematic outline of logic then Electricians would receive a schematic outline of logic then implement the logic with relays.implement the logic with relays.

The schematic was commonly called “Ladder Schematic”The schematic was commonly called “Ladder Schematic”

The Ladder displayed all switches, sensors, motors, The Ladder displayed all switches, sensors, motors, valves, relays etc in the system.valves, relays etc in the system.

Problems: Long commissioning time, Mechanical Reliance, Problems: Long commissioning time, Mechanical Reliance, Any system logic design change required the power to the Any system logic design change required the power to the control board to be isolated stopping production.control board to be isolated stopping production.


General Motors was among the first to recognise a General Motors was among the first to recognise a need to replace the systems “wired control board”need to replace the systems “wired control board”

Hydramatic Division of GM specified the design Hydramatic Division of GM specified the design criteria for the programmable controller in 1968.criteria for the programmable controller in 1968.

Goal – Goal – Eliminate the high cost associated with Eliminate the high cost associated with inflexible, relay controlled systems.inflexible, relay controlled systems.


New Controller Specifications:New Controller Specifications:– Solid State SystemSolid State System– Computer FlexibilityComputer Flexibility– Operate in Industrial Environment (vibrations, heat, Operate in Industrial Environment (vibrations, heat,

dust etc.) dust etc.) – Capability of being reprogrammedCapability of being reprogrammed– Easily programmed and maintained by electricians Easily programmed and maintained by electricians

and technicians.and technicians.


In 1969 Gould Modicon developed the first PLC. In 1969 Gould Modicon developed the first PLC.

Strength – Programmed with Ladder LogicStrength – Programmed with Ladder Logic

Initially called Programmable Controllers PC’s Initially called Programmable Controllers PC’s – Now - PLC’s, Programmable Logic ControllersNow - PLC’s, Programmable Logic Controllers

PLC’s have evolved from simple on/off control to PLC’s have evolved from simple on/off control to being able to communicate with other control being able to communicate with other control systems, provide production reports, schedule systems, provide production reports, schedule production, diagnose machine and process production, diagnose machine and process faults.faults.

Overview of TechnologyOverview of Technology

Basic PLC SchemaBasic PLC Schema

CPUCPU

Power SupplyPower Supply

MemoryMemory

Input BlocksInput Blocks

Output BlocksOutput Blocks

CommunicationsCommunications

Expansion Expansion ConnectionsConnections

CPU ModuleCPU Module

The Central Processing Unit (CPU) The Central Processing Unit (CPU) Module is the brain of the PLC.Module is the brain of the PLC.

Primary role to read inputs, execute Primary role to read inputs, execute the control program, update outputs.the control program, update outputs.

The CPU consists of the arithmetic The CPU consists of the arithmetic logic unit (ALU), timing/control logic unit (ALU), timing/control circuitry, accumulator, scratch pad circuitry, accumulator, scratch pad memory, program counter, address memory, program counter, address stack and instruction register.stack and instruction register.

A PLC works by continually scanning A PLC works by continually scanning a programa program

SelfCheck

ExecuteCode

ScanInputs

UpdateOutputs

PLC ProgramSCAN

MemoryMemory

The memory includes pre-programmed ROM memory The memory includes pre-programmed ROM memory containing the PLC’s operating system, driver containing the PLC’s operating system, driver programs and application programs and the RAM programs and application programs and the RAM memory.memory.

PLC manufacturer offer various types of retentive PLC manufacturer offer various types of retentive memory to save user-programs and data while power memory to save user-programs and data while power is removed, so that the PLC can resume execution of is removed, so that the PLC can resume execution of the user-written control program as soon as power is the user-written control program as soon as power is restored.restored.

Memory cont’dMemory cont’d

Many PLCs also offer removable memory modules, Many PLCs also offer removable memory modules, which are plugged into the CPU module.which are plugged into the CPU module.

Memory can be classified into two basic categories: Memory can be classified into two basic categories: volatile and non-volatile.volatile and non-volatile.

- - Volatile memoryVolatile memory is that which loses state (the is that which loses state (the stored information) when power is removed.stored information) when power is removed.

- - Nonvolatile memoryNonvolatile memory, on the other hand, , on the other hand, maintains maintains the information in memory even if the the information in memory even if the power is power is interrupted. interrupted.

Memory cont’dMemory cont’d

Some types of memory used in a PLC include:Some types of memory used in a PLC include:

ROM (Read-Only Memory)ROM (Read-Only Memory)

RAM (Random Access Memory)RAM (Random Access Memory)

PROM (Programmable Read-Only Memory)PROM (Programmable Read-Only Memory)

EPROM (Erasable Programmable Read-Only Memory)EPROM (Erasable Programmable Read-Only Memory)

EEPROM (Electronically Erasable Programmable Read-EEPROM (Electronically Erasable Programmable Read-Only Memory)Only Memory)

FLASH MemoryFLASH Memory

Compact Flash – Can store complete program Compact Flash – Can store complete program information, read & write text files information, read & write text files

I/O ModulesI/O Modules

Input and output (I/O) modules connect Input and output (I/O) modules connect the PLC to sensors and actuators.the PLC to sensors and actuators.

Provide isolation for the low-voltage, low-Provide isolation for the low-voltage, low-current signals that the PLC uses current signals that the PLC uses internally from the higher-power internally from the higher-power electrical circuits required by most electrical circuits required by most sensors and actuators.sensors and actuators.

Wide range of I/O modules available Wide range of I/O modules available including: digital (logical) I/O modules including: digital (logical) I/O modules and analog (continuous) I/O modules.and analog (continuous) I/O modules.

Inputs ModulesInputs ModulesInputs come from sensors that translate physical or Inputs come from sensors that translate physical or chemical phenomena into electrical signals.chemical phenomena into electrical signals.

The simplest form of inputs are digital/discrete in AC/DC.The simplest form of inputs are digital/discrete in AC/DC.

In smaller PLCs the inputs are normally built in and are In smaller PLCs the inputs are normally built in and are

specified when purchasing the PLC.specified when purchasing the PLC.

For larger PLCs the inputs are purchased as modules, or For larger PLCs the inputs are purchased as modules, or

cards, with 8,16, 32, 64, 96 inputs of the same type on cards, with 8,16, 32, 64, 96 inputs of the same type on

each card.each card.

Inputs ModulesInputs Modules The list below shows typical ranges for input The list below shows typical ranges for input

voltages.voltages.

5 Vdc5 Vdc

12 Vdc12 Vdc

24 Vdc24 Vdc

48 Vdc48 Vdc

12 Vac12 Vac

24 Vac24 Vac

120 Vac120 Vac

240 Vac240 Vac

Example of Input CardExample of Input Card

Outputs ModulesOutputs Modules

Output modules rarely supply any power, but instead act Output modules rarely supply any power, but instead act as switches.as switches.

External power supplies are connected to the output card External power supplies are connected to the output card and the card will switch the power on or off for each and the card will switch the power on or off for each output.output.

A common choice when purchasing output cards is A common choice when purchasing output cards is relays, relays, transistors or triacstransistors or triacs..

Relay are the most flexible output devices. They are Relay are the most flexible output devices. They are capable of switching both AC and DC outputs. But, they capable of switching both AC and DC outputs. But, they are slower, cost more, and they will wear out after millions are slower, cost more, and they will wear out after millions of cycles. of cycles.

RelaysRelays

The most important consideration The most important consideration when selecting relays, or relay when selecting relays, or relay outputs on a PLC, is the rated outputs on a PLC, is the rated current and voltage.current and voltage.

For transistor outputs or higher For transistor outputs or higher density output cards relay terminal density output cards relay terminal blocks are available. blocks are available. – Advantage of individual standard Advantage of individual standard

replaceable relaysreplaceable relays

OutputsOutputs Typical output voltages are listed below, Typical output voltages are listed below,

5 Vdc5 Vdc

12 Vdc12 Vdc

24 Vdc24 Vdc

48 Vdc48 Vdc

24 Vac24 Vac

120 Vac120 Vac

240 Vac240 Vac

WARNING: Always check rated voltages and currents for WARNING: Always check rated voltages and currents for

PLCs and never exceed.PLCs and never exceed.

Example of Output CardExample of Output Card

Analogue CardsAnalogue Cards

Typical Analogue Input Typical Analogue Input

signals are:signals are:– Flow sensorsFlow sensors

– Humidity sensorsHumidity sensors

– Load CellsLoad Cells

– PotentiometersPotentiometers

– Pressure sensorsPressure sensors

– Temperature sensorsTemperature sensors

– VibrationVibration

Analogue Output signals Analogue Output signals control:control:– Analogue ValvesAnalogue Valves– ActuatorsActuators– Chart ResordersChart Resorders– Variable Speed DrivesVariable Speed Drives– Analogue MetersAnalogue Meters

Typical Analogue Signal Typical Analogue Signal LevelsLevels– 4-20mA4-20mA– 1-5 Vdc1-5 Vdc– 0-10 Vdc0-10 Vdc– -10 – 10Vdc-10 – 10Vdc

Analogue Inputs/OutputsAnalogue Inputs/OutputsAnalogue input cards convert continuous signals via a Analogue input cards convert continuous signals via a

A/D converter into discrete values for the PLCA/D converter into discrete values for the PLC

Analogue output cards convert digital values in then PLC Analogue output cards convert digital values in then PLC

to continuous signals via a D/A converter.to continuous signals via a D/A converter.

Resolution can be important in choosing an applicable Resolution can be important in choosing an applicable

cardcard

Example, for a temperature input of 0 to 100 degrees CExample, for a temperature input of 0 to 100 degrees C– For 8 bit resolution the value in the PLC is 0 to 255For 8 bit resolution the value in the PLC is 0 to 255

– For 12 bit resolution the value in the PLC is 0 to 4095For 12 bit resolution the value in the PLC is 0 to 4095

– For 12.5 bit resolution the value in the PLC is 0 to 6000For 12.5 bit resolution the value in the PLC is 0 to 6000



Special ModulesSpecial ModulesRF ID RF ID VoiceVoiceGas Flow CalculationGas Flow CalculationWeigh CellWeigh CellHydraulic ServoHydraulic ServoASCIIASCIIFuzzy LogicFuzzy LogicTemperature SensorTemperature SensorTemperature ControlTemperature ControlHeat/Cool ControlHeat/Cool ControlField Bus CardsField Bus Cards– DeviceNet, Profibus etcDeviceNet, Profibus etc– Lonworks, BACNetLonworks, BACNet

Fast Response (Interrupt)Fast Response (Interrupt)PIDPIDLoop ControllerLoop ControllerBASIC CardsBASIC CardsRS232 Comm’s RS232 Comm’s Modbus ASCII/RTUModbus ASCII/RTUEthernet Comm’sEthernet Comm’sHigh Speed CountersHigh Speed CountersPosition Control CardsPosition Control CardsPer to Per Comm’sPer to Per Comm’s– Controller LinkController Link– DH+DH+– Modbus PlusModbus Plus

Available InstructionsAvailable InstructionsSequenceSequence– InputInput– OutputOutput– ControlControl

LogicLogicTimer and CountersTimer and CountersComparisonComparisonRange ComparisonRange ComparisonData MovementData MovementData ShiftData ShiftStep / Step NextStep / Step NextSerial CommunicationsSerial CommunicationsText String ProcessingText String ProcessingFile ManipulationFile Manipulation

Increment/DecrementIncrement/DecrementConversionConversion– ASCIIASCII– Number SystemsNumber Systems

MathMathFloating Point MathFloating Point MathStatisticsStatisticsScalingScalingPIDPIDPID with Auto tunePID with Auto tuneClock / DateClock / DateBlock ProcessingBlock Processing– IF,THEN,ELSE,LOOPIF,THEN,ELSE,LOOP

Table ProcessingTable Processing– LIFO, FIFOLIFO, FIFO

NetworksNetworks

ASIASI

DevicenetDevicenet

Interbus-SInterbus-S

ProfibusProfibus

InterbusInterbus

FieldbusFieldbus

Ethernet I/PEthernet I/P

Smart Distributed System Smart Distributed System (SDS)(SDS)

SeriplexSeriplex

CANopenCANopen

LonworksLonworks

BACNetBACNet

Gateways enable communications between Gateways enable communications between different network topologiesdifferent network topologies

PLC ConfigurationPLC Configuration

RACK

SHOE BOX

MINI

MICRO

The Configuration of PLCThe Configuration of PLCThe configuration of PLC refers to the packaging of the The configuration of PLC refers to the packaging of the components.components.

Typical configurations are listed below from largest to Typical configurations are listed below from largest to smallest.smallest.– Rack TypeRack Type : A rack can often be as large as 18” by 30” by 10” : A rack can often be as large as 18” by 30” by 10”

– MiniMini: These are similar in function to PLC racks, but about the : These are similar in function to PLC racks, but about the half size. Dedicated Backplanes can be used to support the half size. Dedicated Backplanes can be used to support the cards OR DIN rail mountable with incorporated I/O bus in cards OR DIN rail mountable with incorporated I/O bus in module.module.

– ShoeboxShoebox: A compact, all-in-one unit that has limited expansion : A compact, all-in-one unit that has limited expansion capabilities. Lower cost and compactness make these ideal for capabilities. Lower cost and compactness make these ideal for small applications. DIN rail mountable.small applications. DIN rail mountable.

– MicroMicro: These units can be as small as a deck of cards. They : These units can be as small as a deck of cards. They tend to have fixed quantities of I/O and limited abilities, but costs tend to have fixed quantities of I/O and limited abilities, but costs will be lowest. DIN rail mountable.will be lowest. DIN rail mountable.

Sizing of PLCSizing of PLC

Micro PLCs: I/O up to 32 pointsMicro PLCs: I/O up to 32 points Small PLC: I/O up to 128 pointsSmall PLC: I/O up to 128 points Medium PLC: I/O up to 1024 pointsMedium PLC: I/O up to 1024 points Large PLC: I/O up to 4096 pointsLarge PLC: I/O up to 4096 points Very Large: I/O up to 8192 pointsVery Large: I/O up to 8192 points

Selecting a PLCSelecting a PLCCriteriaCriteria

Number of logical inputs and outputsNumber of logical inputs and outputs

MemoryMemory

Number of special I/O modulesNumber of special I/O modules

Expansion CapabilitiesExpansion Capabilities

Scan TimeScan Time

CommunicationCommunication

SoftwareSoftware

SupportSupport

Dollars Dollars

Selecting Selecting a PLCa PLC

Example of PLC SpecificationsExample of PLC Specifications

ManufacturesManufactures

OMRONOMRON

Allen BradleyAllen Bradley

Schneider (Modicon, Telemecanique, Square D)Schneider (Modicon, Telemecanique, Square D)

GE FanucGE Fanuc

SiemensSiemens

Automation Direct (Koyo)Automation Direct (Koyo)

ToshibaToshiba

MitsubishiMitsubishi

HitachiHitachi

KeyenceKeyence

FestoFesto

EberleEberle

Texas InstrumentsTexas Instruments

AprilApril

Major BrandsMajor Brands


Ladder Logic remains the most common Ladder Logic remains the most common technique for programming PLC’stechnique for programming PLC’s

PLC StandardizationPLC StandardizationOpen ControllerOpen Controller

IEC 61131IEC 61131– Based on IEC 1131 (1992) standard, developed to be Based on IEC 1131 (1992) standard, developed to be

a common and open framework for PLC architecture. a common and open framework for PLC architecture.

IEC 61131-1 OverviewIEC 61131-1 OverviewIEC 61131-2 Requirements & Test ProceduresIEC 61131-2 Requirements & Test ProceduresIEC 61131-3 Data Types & ProgrammingIEC 61131-3 Data Types & ProgrammingIEC 61131-4 User GuidelinesIEC 61131-4 User GuidelinesIEC 61131-5 Communications IEC 61131-5 Communications IEC 61131-7 Fuzzy ControlIEC 61131-7 Fuzzy ControlIEC 61131-7 Guidelines for the application and IEC 61131-7 Guidelines for the application and implementation of programming languagesimplementation of programming languages

IEC 61131-3IEC 61131-3

IL (Instruction List) – mnemonic programmingIL (Instruction List) – mnemonic programming

LD (Ladder Diagram) – Relay logicLD (Ladder Diagram) – Relay logic

ST (Structured Text) – A BASIC like programming ST (Structured Text) – A BASIC like programming languagelanguage

FDB (Functional Block Diagram) – Graphical dataflow FDB (Functional Block Diagram) – Graphical dataflow programming languageprogramming language

SFC (Sequential Flow Chart) – Graphical method for SFC (Sequential Flow Chart) – Graphical method for structured programsstructured programs

IEC 61131-3 ExamplesIEC 61131-3 ExamplesInstruction List Ladder

Sequential Flow Chart

Structured Text

Function Block

PLC’s in HVAC controlPLC’s in HVAC control

PLC’s in HVAC controlPLC’s in HVAC control

Despite the versatility of today’s PLC’s, Despite the versatility of today’s PLC’s, many controls professionals are skeptical of many controls professionals are skeptical of applying PLC’s to new applications such as applying PLC’s to new applications such as HVAC control.HVAC control.

Reasons included : Reasons included : – Lack of knowledge of these systemsLack of knowledge of these systems– Requirement for programmingRequirement for programming– Lack of initial capability of technologyLack of initial capability of technology– Premium first up costPremium first up cost

AdvantagesAdvantages

PLC’s remain a predominate piece of equipment PLC’s remain a predominate piece of equipment on the factory floor and will probably remain so for on the factory floor and will probably remain so for some time to come.some time to come.The advantages they offer are:The advantages they offer are:– Cost effective for controlling complex systemsCost effective for controlling complex systems– Flexible and can be reapplied to control other systems Flexible and can be reapplied to control other systems

quickly and easilyquickly and easily– Computational abilities allow more sophisticated controlComputational abilities allow more sophisticated control– Trouble shooting aids make programming easier and Trouble shooting aids make programming easier and

reduce downtimereduce downtime– Reliable components (high MTBF) ensure operation for Reliable components (high MTBF) ensure operation for

yearsyears

Advantages continued….Advantages continued….– Variety of I/O interfacesVariety of I/O interfaces– Small sizeSmall size– Growing with technology, faster scan times, capability Growing with technology, faster scan times, capability

etcetc– Quick I/O disconnects that aids in field servicingQuick I/O disconnects that aids in field servicing– Modularity in hardware architectureModularity in hardware architecture– Modularity in software design (programmer Modularity in software design (programmer

dependant)dependant)– Software Timers/Counter, RelaysSoftware Timers/Counter, Relays– Clean failure modeClean failure mode– On-line programmingOn-line programming– Self inspecting for operation code during executionSelf inspecting for operation code during execution– Availability of programmers/trouble Availability of programmers/trouble

shooters/integratorsshooters/integrators– Availability of replacement partsAvailability of replacement parts

BenefitsBenefits

The benefits achieved with programmable The benefits achieved with programmable controllers will grow with the individual using controllers will grow with the individual using them: them:

““The more you learn about PLC’s, the more you The more you learn about PLC’s, the more you will be able to solve other control problems.”will be able to solve other control problems.”

ExamplesExamplesSouthgate – MelbourneSouthgate – Melbourne

Millennium Dome – LondonMillennium Dome – London

Woolworths – BritainWoolworths – Britain

ST Microelectronics – FranceST Microelectronics – France

Einstein III Building - MunichEinstein III Building - Munich

Web TechnologiesWeb Technologies

Web Enabled Automation...?Web Enabled Automation...?

Is it just more Internet hype or is there Is it just more Internet hype or is there some benefit behind the idea.some benefit behind the idea.

Is it possible to connect all of these Is it possible to connect all of these systems by their PLC’s to the Internet ?systems by their PLC’s to the Internet ?

Is it practical ?Is it practical ?

Is it profitable ?Is it profitable ?

Short Answers……Short Answers……Internet access can provide compelling Internet access can provide compelling competitive advantages linking customers, competitive advantages linking customers, suppliers, subcontractors, front line management.suppliers, subcontractors, front line management.– Improve fault reporting and response timeImprove fault reporting and response time– Enhance flexibilityEnhance flexibility– Optimise process control Optimise process control

Proven affordable technologies are readily Proven affordable technologies are readily available to connect any PLC, Process Controller available to connect any PLC, Process Controller or I/O to the Internet and Intranet.or I/O to the Internet and Intranet.

Process to Internet access has the potential to Process to Internet access has the potential to become a standard utility.become a standard utility.

What is Web EnablingWhat is Web Enabling

Web enabling gives real time access to data and Web enabling gives real time access to data and control, virtually anytime, anywhere.control, virtually anytime, anywhere.

It uses communication with any manufactures It uses communication with any manufactures PLC or I/O to send information via the Internet to PLC or I/O to send information via the Internet to anywhere in the world.anywhere in the world.

Web enabled automation drives real-time Web enabled automation drives real-time accessibility “accessibility “Vertically Down” Vertically Down” to the control to the control device level.device level.

What can we do with it ?What can we do with it ?

Check real time process data without waiting for Check real time process data without waiting for end of shift reportsend of shift reportsTrack equipment run time and initiate Track equipment run time and initiate maintenance requestsmaintenance requestsAutomatically notify a technician via email or Automatically notify a technician via email or GSM phone etc of faults and allow rectificationGSM phone etc of faults and allow rectificationCollect process data on a server PC and Collect process data on a server PC and analyse with statistics and control (SPC)analyse with statistics and control (SPC)Use HTML help files including graphicsUse HTML help files including graphicsMonitor and control remote operations reducing Monitor and control remote operations reducing field staffing and unnecessary travelfield staffing and unnecessary travel

What pieces and parts are required ?What pieces and parts are required ?

InterfaceInterface

Web Server Web Server

Data ServiceData Service

BrowserBrowser

InterfaceInterface

An interface to the equipment to be monitored An interface to the equipment to be monitored and controlled via the web (network) connectionand controlled via the web (network) connection– Ethernet LineEthernet Line– Modem / Phone lineModem / Phone line– ISDNISDN– Wireless Modem (eg 802.11b Ethernet)Wireless Modem (eg 802.11b Ethernet)

Type of connection is typically determined by the Type of connection is typically determined by the thin server and the existing network thin server and the existing network infrastructure – or lack thereofinfrastructure – or lack thereof

Web Server (or “thin server” data service) to Web Server (or “thin server” data service) to enable the remote browser to view the desired enable the remote browser to view the desired displays and web pages.displays and web pages.

– Typical installation requires a connection to an Typical installation requires a connection to an existing PLC or proprietary controller.existing PLC or proprietary controller.

– Most PLC’s support at least a serial connection using Most PLC’s support at least a serial connection using the vendor supplied protocol to communicate.the vendor supplied protocol to communicate.

– Use an Open network controller (interface)Use an Open network controller (interface)– Some PLC’s have Web Servers built into their Some PLC’s have Web Servers built into their

Ethernet Units.Ethernet Units.

Web ServerWeb Server

Data ServiceData Service

A data service or interface to handle exchanging A data service or interface to handle exchanging data between the local equipment/ process data between the local equipment/ process (server) and the remote system (client)(server) and the remote system (client)

– A common “language”, protocol is required..A common “language”, protocol is required..– XML (Extended Markup Language)XML (Extended Markup Language)– Benefit of XML is its independence from senders and Benefit of XML is its independence from senders and

receivers hardware, OS, and application.receivers hardware, OS, and application.

Browser InterfaceBrowser Interface

Use the thin servers assigned IP address to Use the thin servers assigned IP address to access the remote system.access the remote system.Simple browsing requires standard browser Simple browsing requires standard browser interface found on a desktop computer, PDA, interface found on a desktop computer, PDA, WAP, or “Thin Client”WAP, or “Thin Client”For application information sharing (SPC, For application information sharing (SPC, Enterprise Software), if the thin server and Enterprise Software), if the thin server and remote application software support a common remote application software support a common interface such as OPC, setting up the data interface such as OPC, setting up the data exchange can be accomplished in a couple of exchange can be accomplished in a couple of minutesminutes

New term … OPCNew term … OPC

OOLE for LE for PProcess rocess CControlontrol

OObject bject LLinking and inking and EEmbeddingmbedding

One of industries most popular standardsOne of industries most popular standards

Maintained by OPC foundationMaintained by OPC foundation

OPC standard is non proprietary technical OPC standard is non proprietary technical specification based on Microsoft's specification based on Microsoft's OLE/DCOM technology.OLE/DCOM technology.

www.opc.orgwww.opc.org

Web ServersWeb ServersComputer Based DisplaysComputer Based DisplaysSCADA – Supervisory Control and Data AcquisitionSCADA – Supervisory Control and Data AcquisitionCitect, Wonderware, Fix, Iconics, GeniusCitect, Wonderware, Fix, Iconics, Genius– Ethernet, Serial, OPC (OLE for Process Control), Dedicated Ethernet, Serial, OPC (OLE for Process Control), Dedicated

Computer Boards for Propriety BusesComputer Boards for Propriety Buses

Dedicated Packages for BMS Dedicated Packages for BMS – Citect SCADA FacilitiesCitect SCADA Facilities

Embedded Web ServersEmbedded Web ServersOpen Network Controller Interface – GatewayOpen Network Controller Interface – GatewayEmbedded Web Servers in PLC’s Ethernet cardsEmbedded Web Servers in PLC’s Ethernet cardsNew Dedicated HMI Screens – some have embedded Web New Dedicated HMI Screens – some have embedded Web ServersServersExample of Web Technology visit www.WebHMI.comExample of Web Technology visit www.WebHMI.com

Thank you….Thank you….

Questions ?Questions ?

Programmable Logic Controllers PLC’s An Overview, Use in HVAC and Web Technologies By Sleepy...

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