labview dsc - sve.pdf

8/10/2019 LabVIEW DSC - SVE.pdf

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LabVIEW

Datalogging and Supervisory Control
http://www.ni.com/


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SCADA ?

Data Server

Supervisory

Control And Data

Acquisition

Graphics and Batch processing Archiving, Logging, Access

Control, Alarms

Distributed database

PLCs

Field Bus

Data Server

Control Programs

ERP Systems

Expert Systems
http://www.ni.com/http://../www.ni.com/http://../ni.com/


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What do SCADA Provide?

Flexible and open architecture

Basic SCADA functionality MMI

Alarm Handling and Trending

Access Control

Automation

Logging, Archiving, Report Generation

Interfaces to H/W and S/W

Interfaces to ERP- and Expert-Systems Development Tools


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Why is OPC Data Access needed?

Software

Driver

Software

Driver

Software

Driver

Software

Driver

Display

Application

Trend

Application

Report

Application


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How does OPC Solve the Problem?

Software

Driver

Software

Driver

Software

Driver

Software

Driver

OPC OPC OPC OPC

DisplayApplication TrendApplication ReportApplication

OPC OPC OPC


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OPC and SCADA TAGs

PLCPrograms

CommunicationProcessor

Analog-InputValue-AI-0Value-AI-1

Analog-OutputValue-AO-0

Value-AO-1 Field Bus

Analog-InputVacuum_VALUEPressure_VALUE

Analog-OutputValve_1_OUT

Heater_1_OUT

Mapping

SCADA At a high level, an OPCserver is comprised of

several objects: the server,

the group, and the item.

The items are not the data

sources, they are just

connections to them. For

example, the tags in a

DCS system exist

regardless of whether anOPC client is currently

accessing them


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What is the DSC module?

The DSC Module extends theLabVIEW graphical development

environment with additional

functionality for the rapid development

of distributed measurement, control,

and high-channel-count monitoringapplications.

The DSC Module provides tools for

graphing historical or real-time trends,

enhancing the security of front panels,

and writing custom I/O servers.


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What is the DSC module?

The DSC Module also enhances the LabVIEW sharedvariable. Use the shared variable to access and pass

data among several VIs in a LabVIEW project or

across a network.A shared variable can represent a value or an I/O

point. With the DSC Module, you can log data

automatically; add alarming, scaling, and security tothe shared variable; and configure the shared variable

programmatically.


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Industrial Automation Graphics


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Engine

Event-driven I/O processing

Alarm & Event management

Trending

Networking

Logging

ScalingDatabase

(Citadel)

Architecture

OPCServers VIs DDE DataSocket

Utilities VIs Wizards

LabVIEW


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Citadel

The DSC Module logs shared variable data tothe Citadel database. The Citadel database

stores historical data, alarms, and events.

You can access and view Citadel data using

the Historical Data Viewer and using the

Historical VIs. Use the Historical Data Viewer to view data

stored in the Citadel database. Select Tools

DSC Module View Historical Data to

launch the Measurement & Automation

Explorer (MAX). Expand the Historical Data

category to select a database that appears

under Citadel 5 Universe.


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Projects


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Using Shared Variables


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Network published SV

Using the network-published sharedvariable, you can write to and read from

shared variables across an (Ethernet

network). The networking implementation

is handled entirely by the network-

published variable. The NI Publish and Subscribe Protocol

(NI-PSP) is a networking protocol

optimized to be the transport for Network

Shared Variables.

LogosXT is the layer of the stack

responsible for optimizing throughput for

the shared variable.


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Hosting and Deploying

You must deploy network-published shared variables to a

shared variable engine (SVE)

that hosts the shared variable

values on the network.

When you write to a sharedvariable node, LabVIEW sends

the new value to the SVE that

deployed and hosts the variable.

The SVE processing loop then

publishes the value so that

subscribers get the updated

value.


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SVE and OPC

The SVE is 3.0 compliant and can act as an OPC server on Windows machines.Any OPC client can write to or read from a shared variable hosted on a Windows

machine.

When you install the LabVIEW DSC Module on a Windows machine, the SVE

also can act as an OPC client.


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I/O servers An I/O server is a SVE plug-in that

enables communication with devicesand applications that do not use

National Instruments proprietary NI

Publish-Subscribe Protocol (NI-PSP).

I/O servers are the bridging elements

between shared variables in a

LabVIEW VI and data tags in OPC

I/O servers plug into the SVE to

provide a list of items available for

subscription and to provide that datato the SVE.


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Using LabVIEW as an OPC Client The LabVIEW Datalogging and Supervisory Control (DSC) Module provides

OPC Client I/O servers for communicating with any server implementing theOPC Foundation OPC-DA protocol (a Microsoft COM-based standard).

An OPC Client I/O server lists all OPC servers installed on the computer and

makes accessible groups and items on the server.


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Using LabVIEW as an OPC Server The SVE can act as an OPC server.

The SVE can take a network-published Shared Variable and create OPC tagsthat an OPC DA client can connect to. This allows LabVIEW VIs to easily

communicate with other OPC client software.

The SVE can bind a network-published Shared Variable to the values being read by the DAQ

device. The SVE then uses OPC DA standards to create OPC tags for the Shared Variable. In

this way, an OPC client can read and write to the DAQ device

labview dsc - sve.pdf

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