OPC UA Inside Out, Part 1 - Introduction and Playing Field

© Utthunga Technologies Pvt. Ltd. 2020
OPC UA Inside Out
Part 1 - Introduction and Playing field

Company Overview
Germany
500+
PROFESSIONALS USA
Japan
12
HQ & Development Centre:
Bangalore India
SERVICES SOLUTIONS
Product FOCUS
Engineering IIoT, Cloud & Big
Data Analytics
Embedded
Software
& Hardware
Digital
Services
Solutions
Quality
Engineering
Application
Software
Engineering
Process
& Factory
Power &
Utilities
Data
Connectivity
& Integration
Solutions
Custom
Solutions

Industry Associations
 Part of various Special Interest Groups
(Technical Specifications, Architecture, Test
& Certification and Marketing)
 Involved in reference Application
Architecture, Design and Development
 Technology Outsourcing Partner
 PROFIBUS and PROFINET Competency
Center
 FDT Test & Certification Center
 Part of Global Expert/Certified Community
https://opcfoundation.org/about/opc-foundation/experts/
https://www.profibus.com/pi-organization/certified-people/

Speakers for today
Chatrapathi
About Speaker
 15+ years of Industry Experience
 Listed as Expert by OPC Foundation
 Participates and contributes in OPC UA Specification working group activities.
 Member of OPC Foundation and ODVA Joint Specification Working Group
 Wrote and presented White papers at ODVA Industrial Conference and IEEE.
 Familiar with different OPC UA stacks, DDS stacks, application development around
OPC UA especially embedded devices, Information models, performance
optimization, etc.,
 Familiar with different Industrial automation protocols like EtherNet/IP, Modbus,
BACnet etc.,

Speakers for today
Thilak SR
About Speaker
 Listed as Expert by OPC Foundation
 Active member and contributor to OPC Foundation Working Group (OPC Pub/Sub
Working Group)
 Contractor for OPC Foundation related activities like development of OPC Pub/Sub
Configuration tool, Publisher and Subscriber
 Have good understanding of OPC UA on Devices Companion specifications, FDI
Information Model, FDI Communication Devices Information Model etc.
 Active member of FDT OPC UA Specification Working group
 Developed the prototype of FDT OPC UA Server for FDT OPC UA Specification
Working Group.

4. OPC UA Security – Transport & Application Layer
3. OPC UA Transports – Client/Server & Pub/Sub
2. OPC UA Base Concepts – Information Model & Base Services
1. Introduction on OPC – Why OPC, RAMI 4.0, NOA, IIRA
6. OPC UA Discovery – LDS, LDSme & GDS
5. OPC UA Scalability – Profiles & Conformance Units
Agenda

Why OPC
Before OPC After OPC
HART
Driver
Modbus
Driver
Profibus
Driver
HART
Driver
Modbus
Driver
Profibus
Driver
HART
Driver
Modbus
Driver
Profibus
Driver
Vendor A Vendor B Vendor D Vendor A Vendor B Vendor D
OPC Client
OPC Server
OPC Client OPC Client
HART
Driver
Modbus
Driver
Profibus
Driver
 Proprietary Protocols
 Custom Drivers
 Complex Integration
 Device and Controller Loading
Automation’s Data Connectivity Problem… OPC Solutions…
 Unnecessary for the OPC Client to know how device organizes its data.
 Eliminates the need for custom drivers between each new application and
Device.
 Simplifies Complex Integration, no concern for additional custom Drivers.
 OPC connector requires only a single connection to the Device.

OPC – OLE for Process Control
 Closely tied to Microsoft Windows and its base technology COM/DCOM
 Configuration requires expensive expertise and complicates the use of OPC
Limitations:
 Platform dependency
 Limited Security
 Does not work across the network
 No Support of complex data types like hierarchical data types

History – Use Case Driven
 Definition 2003 – 2006
 Verification and Implementation 2006 – 2008
 Final OPC Foundation Release 2009
 IEC 62541 Release 2010 – 2012
 OPC Pub/Sub specification – 2018
OPC UA = established OPC features
 Platform independence
 Standard internet and IP based protocols
 Built in security features
 Generic object model
 Extensible type system
 Scalability through profiles
 Migration path from Classic OPC
Expose Data
Device
OPCUA
Consume Data
System

OPC UA – Reference Architecture Model Industrie 4.0 (RAMI 4.0)
Standardization of Industrie 4.0 to have uniform structure and
uniform wording.
Defines 3 dimension model
1. Factory- Products, Field Device, Control Device and so on
2. Product Life cycle: Development, Production Maintenance
usage
3. Architecture: Assets, Integration, Communication and so
on.
OPC UA is used in the communication layer as a standard

OPC UA – NAMUR Open Architecture (NOA)
 Used to Establish a direct link from field level to the
Cloud
 proposes the enhancement to the existing legacy
systems for the efﬁcient utilization of Industrie 4.0
 OPC UA specifies as the standard interface to access
the device information over heterogeneous network

OPC UA – Industrial Internet Reference Architecture (IIRA)
 IIoT core concepts and technologies are addressed-
Proposed by IIC
 IIRA explains IIoT system architecture, value proposition
from the business as well as technical perspective.
 Connectivity frameworks covering various industries.
OPC UA is used as the connectivity standard

Information Model
OPC UA = Information Centric Layered Architecture
 Basic rules for exposing information with OPC UA
 Generic Object Model, extendabel Type System
 Built-In Models for:
 Data Access
 Alarms Conditions
 Historic Data & Events
 Programs
 Device Description
OPC UA Meta Model
Built-In Information Models
Companion Information Models
Vendor Specific Extensions

Nodes and References
 Everything in the UA Address Space is a Node
 UA defines a none extensible list of 8 Node Classes
 Each Node Class has a defined set of Attributes
 Nodes are connected by References
BaseNode
+NodeId : NodeId
+NodeClass : NodeClass
+BrowseName : QualifiedName
+DisplayName : LocalizedText
+Description : LocalizedText
Object
+EventNotifier : Byte
ReferenceType
+IsAbstract : Boolean
+Symmetric : Boolean
+InverseName : LocalizedText
View
+ContainsNoLoops : Boolean
+EventNotifier : Byte
ObjectType
Variable
+Value
+DataType : NodeId
+ValueRank : Int32
+ArrayDimensions : Int32
+AccessLevel : Byte
+UserAccessLevel : Byte
+MinimumSampleInterval : Int32
+Historizing : Boolean
VariableType
+Value
+DataType : NodeId
+ArraySize : Int32
Method
+Executable : Boolean
+UserExecutable : Boolean
DataType

Object Type (Class)
 Analog Measurement Type is part of Built-In Data Access Model
Object Type
Analog Measurement
ObjectType
Object
Variable
BaseObjectType
ObjectTypes
Organizes
AnalogMeasurement Measurement InstrumentRange
EURange
EngineeringUnits
H_Level
HH_Level
LL_Level
L_Level
SystemAlarm
LevelAlarm

Object Type & Object Instance
Objects
Preasure
H_Level
HH_Level
LL_Level
L_Level
BaseObjectType
ObjectTypes
Organizes
AnalogMeasurement Measurement InstrumentRange
EURange
EngineeringUnits
Measurement InstrumentRange
EURange
EngineeringUnits
SystemAlarm
LevelAlarm
H_Level
HH_Level
LL_Level
L_Level
SystemAlarm
LevelAlarm
Temperature_1
Temperature_2
Values

Companion Models
OPC Foundation collaborates with organizations and
domain experts
 OPC UA defines HOW
 Domain experts define WHAT
 PLCopen
 FDI, FDT
 BACnet
 MDIS
 ISA95
 AutomationML
 MTConnect
 IEC 61850/61400 and more coming
OPC UA Meta Model

Service - Protocol Independent
OPC UA Client/Server Communication Model
 Client-friendly API to access information in the server
 Service Sets
 SecureChannel Service Set
 Session Service Set
 NodeManagement Service Set
 Attribute Service Set (read/write)
 Method Service Set (invoke)
 MonitoredItem Service Set
 Subscription Service Set
OPC UA Meta Model
Client-Server
Services

Protocol Binding – Client/Server
Service Oriented Architecture – Request-Response
 UA TCP (mandatory)
 Binary Encoding
 UA TCP Transport
 Webservice (deprecated)
 XML Encoding
 HTTP/HTTPS Transport
 Hybrid (optional)
 Binary Encoding
 TLS Transport
OPC UA Meta Model
Client-Server
Services
Protocols

Client/Server Communications
Server
Client
Client
Client
Server
TCP based Request/Response
 Connection/session context required (peer-to-peer)
 Save transport, acknowledgement of every message
 Polling for “DataChange”
 Keep alive subscription for each client
 Higher resource consumption

Client/Server vs. Publish/Subscribe
OPC UA Server
Address Space
Subscriber NSubscriber 1OPC UA
Client and
Subscriber A
Client A Session
Publish
Message Oriented Middleware
Subscription
DataSetWriter
DataSet
Publisher
OPC UA
Application
Pub-Sub = optimized Subscription
 Best effort high speed data streaming (UDP)
 Cloud connectivity with AMQP and MQTT
 Offloading of message distribution to broker
 Real-time with TSN support
Constraints
 Only preconfigured data and event streaming
 Configuration requires Client-Server
Image Source:- OPC Foundation

Publish/Subscribe Communications
UDP based Pub/Sub
 Connection-less, broadcast-style communication
 Fire and forget transportation (data loss)
 “Public” subscription, same data for all clients
 Low resource consumption
 Cyclic publish of “all” data (deterministic via TSN support)
 Use Case: small amount of fixed data
Publisher
Subscriber
Broker
Publisher
Subscriber

Pub/Sub - Released
Utility Type Specification Parts
Part 13 - Aggregates
Part 12 - Discovery
Part 14 – Pub/Sub
Released February 2018
v1.04

Extension – Publish/Subscribe
OPC UA Meta Model
Built-In Information ls
Client-Server
Services
Protocols
Pub-Sub
Model
OPC UA Pub/Sub Communication Model
(Part 14, v1.04)
 Generic Pub/Sub Information Model
 Pub/Sub Configuration
 Connections
 Meta Data (description)
 Data Sets (content)
 Security Configuration
 Groups
 Keys
 Extension, but no change to existing OPC UA

Protocols – Publish/Subscribe
Message Oriented - Publish/Subscribe pattern
 Different Use Cases: one-to-many, Cloud, determinism
 Different Protocols
 AMQP, MQTT
 UADP over TSN
OPC UA Meta Model
Built-In Information m..
Client-Server
Services
Protocols
Pub-Sub
Model
Protocols

Protocols – Publish/Subscribe
 OPC UA specific selection of events or life data to be included in
messages
 Messaging protocol specific encoding and transport
 Different protocols can be supported e.g. AMQP, MQTT
Network
Message
Writer
OPC UA
Server’s
Information Space
Filtered
List of
Values
Data Set
Collector
Different
Encoding
Options
UADP
AMQP
MQTT
JSON
UA Binary
Data Set
Writer
F
Values
Events
DataSet
MetaData ----
----
----
Network
Message

OPC UA – Communication Framework
deterministic
Information Model
configuration Client/Server
Publish/Subscribe
Device / Data
acyclic
controller-controller
OPC UA
Device
on demand
read/write/browse/invoke/notify
UA Client Cloud
Broker
cyclic
controller-controller
meta data
security
redundancy
file transfer
events
historical
TSN
Request/Response
Publish/Subscribe

Security for both Communications
Client/Server Security (layered architecture)
 PKI and asymmetric algorithms to exchange session
keys
 Session keys are used for communication with
symmetric algorithms
 Session keys are frequently rotated
 Authentication of Applications
 Authentication of Users
 User/Role based Authorization
 Auditing relevant operations
 Availability
Client Server
Srv
----
----
Cli
----
----
storestore
X509
X509
Graphic: copyright ascolab GmbH

Security for both Communications
Pub/Sub Security (end-to-end)
 Session keys must be shared between Publishers and
Subscribers
 Keys are managed for a security group
 Messages are sent in the context of a security group
 Key distribution is done with OPC UA Client-Server security
 Authentication and Authorization during access to security
group at key server
Message
Oriented
Midleware
Directory
Query
Publisher Subscriber
Subscriber
SubscriberKey
Server
Key
Server
Register
GetKey
GetKey

OPC Profiles – Scale for Embedded
 Conformance Unit
 Represents specific feature
 Defines a list of test cases for the feature
 Profile
 Profiles : Nano, micro, embedded and standard
 Facets : Data Access, Security Policy etc.,
 Flexible : combination of Profiles and Facets.
 Certification Test
 Vendor defines list of supported Facets
 Certification Test executes test cases
 End users can rely on tested Products
Profile
Conformance
Unit
Conformance
Unit
Test
Cases
Test
Cases
Certification Test

OPC Foundation Website
https://apps.opcfoundation.org/profilereporting/

Local Discovery Server (LDS)
PLC PC
OPC UA
Client
OPC UA
Client
OPC UA
Client
OPC UA
Server
OPC UA
Server
LDSOPC
UA Server
LDS Register
Discovery with LDS:
 Network nodes with OPC UA server must be known
 Servers register with local LDS or have LDS included
 LDS is running on defined port (4840)
 LDS provides Server and Endpoint Discovery for local
network node
 Manual security configuration

LDS ME – Multicast Extension
Features provided:
 Host name resolution without central DNS server
 Find network nodes with OPC UA in local network
Advantage:
 No central infrastructure required
Limitation:
 Works only in local subnet
PLC PC
OPC UA
Client
OPC UA
Client
OPC UA
Client
OPC UA
Server
OPC UA
Server
LDSOPC
UA Server
LDS
LDS-MELDS-MELDS-ME
Zeroconf
mDNS

Global Discovery Server (GDS)
PLC PC
OPC UA
Client
OPC UA
Client
OPC UA
Client
OPC UA
Server
OPC UA
Server
LDSOPC
UA Server
LDS Register
GDS Features:
 Certificate creation / management
 Certificate Authority (CA)
 Management of Certificate Revocation Lists (CRL)
 Push / Pull of Certificates / CRL
 Network wide server registry
Central Server
GDS (Port:4840)
Pull / Push
Certificates
Certificate
Authority (CA)
List of registered UA Servers
• Security Config
• Register Server
• Security Config
• Find Servers
• Certificate Rollout
• Plant wide central
security management

Webinars : Up-Coming
4. OPC UA Inside Out Part 5 -Cloud Connectivity – 25th June 2020
3. OPC UA Inside Out Part 4 –Tunneller – 11th June 2020
2. OPC UA Inside Out Part 3 -Edge Gateway – 28th May 2020
1. OPC UA Inside Out Part 2 - Embedded & constrained devices – 14th May 2020
5. OPC UA Inside Out Part 6 - Green Field and Brown Filed – 09th July 2020

Utthunga Technologies Pvt. Ltd.
No. 8, 27th Cross, 2nd Stage,
Banashankari, Bangalore – 560 070
Phone: +91-80-68151900
Mail: contact@utthunga.com

OPC UA Inside Out, Part 1 - Introduction and Playing Field

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