LabVIEW Datalogging and Supervisory Control

SCADA ?

Data Server

SupervisoryControl

And DataAcquisition

Graphics and Batch processing Archiving, Logging, Access Control, Alarms

Distributed database

PLC’s

Field Bus

Data Server

Control Programs

ERP SystemsExpert Systems

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

Why is OPC Data Access needed?

SoftwareDriver

SoftwareDriver

SoftwareDriver

SoftwareDriver

DisplayApplication

TrendApplication

ReportApplication

How does OPC Solve the Problem?

SoftwareDriver

SoftwareDriver

SoftwareDriver

SoftwareDriver

OPC OPC OPC OPC

DisplayApplication

TrendApplication

ReportApplication

OPC OPC OPC

OPC and SCADA TAGs PLC

ProgramsCommunication

Processor

•Analog-Input•Value-AI-0•Value-AI-1

•Analog-Output•Value-AO-0•Value-AO-1

Field Bus

•Analog-Input•Vacuum_VALUE•Pressure_VALUE

•Analog-Output•Valve_1_OUT•Heater_1_OUT

Mapping

SCADA At a high level, an OPC server 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 an OPC client is currently accessing them

What is the DSC module? • The DSC Module extends the

LabVIEW graphical development environment with additional functionality for the rapid development of distributed measurement, control, and high-channel-count monitoring applications.

• The DSC Module provides tools for graphing historical or real-time trends, enhancing the security of front panels, and writing custom I/O servers.

What is the DSC module?

• The DSC Module also enhances the LabVIEW shared variable. 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 to the shared variable; and configure the shared variable programmatically.

Industrial Automation Graphics

Engine

• Event-driven I/O processing

• Alarm & Event management

• Trending

• Networking

• Logging

• Scaling Database (Citadel)

Architecture

OPC Servers VIs DDE DataSocket

Utilities VIs Wizards

LabVIEW

Citadel • The DSC Module logs shared variable data to

the 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”.

Projects

Using Shared Variables

Network published SV • Using the network-published shared

variable, 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.

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 shared variable 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.

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.

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

enables communication with devices and 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 data to the SVE.

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 the OPC 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.

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 tags

that 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