OPC UA Protocol

Overview
Quick Link
Key Features
Communication Models
Service Sets
Node Classes
Built-in Data Types
Security Features
Message Security Modes
User Token Types
Error Codes

Overview

OPC UA (OPC Unified Architecture) is a machine-to-machine communication protocol for industrial automation. It is designed to provide a secure and reliable way to exchange data between industrial systems and devices.

Quick link

Related Protocols: SECS/GEM | Modbus | EtherNet/IP | RTSP

Key Features

Platform Independence: Works across different operating systems and hardware
Security: Built-in security features including encryption and authentication
Scalability: Supports both small and large-scale deployments
Extensibility: Flexible information model that can be extended
Reliability: Robust error handling and recovery mechanisms
Interoperability: Standard-based protocol ensuring vendor independence

Communication Models

Model	Description	Use Case
Client-Server	Traditional request-response model	Configuration, monitoring, data access
Pub-Sub	Publish-subscribe model	Real-time data distribution
Discovery	Service discovery and registration	Network topology discovery

Service Sets

Service Set	Description	Functions
Discovery	Find and connect to servers	GetEndpoints, FindServers
Session	Manage client-server sessions	CreateSession, ActivateSession
Node Management	Manage address space nodes	AddNodes, DeleteNodes
View	Browse address space	Browse, BrowseNext
Query	Query data from address space	QueryFirst, QueryNext
Attribute	Read/write node attributes	Read, Write
Method	Call methods on nodes	Call
Subscription	Manage subscriptions	CreateSubscription, DeleteSubscriptions
MonitoredItem	Monitor data changes	CreateMonitoredItems, DeleteMonitoredItems
Publish	Publish data changes	Publish

Node Classes

Node Class	Description	Purpose
Object	Represents real-world objects	Physical devices, systems
Variable	Contains data values	Process values, parameters
Method	Defines callable functions	Commands, operations
ObjectType	Defines object structure	Type definitions
VariableType	Defines variable structure	Data type definitions
ReferenceType	Defines relationships	Node relationships
DataType	Defines data structures	Custom data types
View	Organizes address space	Logical grouping

Built-in Data Types

Type	Description	Size
Boolean	True/false value	1 bit
SByte	8-bit signed integer	1 byte
Byte	8-bit unsigned integer	1 byte
Int16	16-bit signed integer	2 bytes
UInt16	16-bit unsigned integer	2 bytes
Int32	32-bit signed integer	4 bytes
UInt32	32-bit unsigned integer	4 bytes
Int64	64-bit signed integer	8 bytes
UInt64	64-bit unsigned integer	8 bytes
Float	32-bit floating point	4 bytes
Double	64-bit floating point	8 bytes
String	Unicode string	Variable
DateTime	Date and time	8 bytes
Guid	Globally unique identifier	16 bytes
ByteString	Byte array	Variable

Security Features

Feature	Description	Purpose
Transport Security	TLS/SSL encryption	Secure communication
Application Authentication	Certificate-based authentication	Server/client verification
User Authentication	Username/password, certificates	User identity verification
Authorization	Access control policies	Resource access control
Audit Logging	Security event logging	Compliance and monitoring

Message Security Modes

Mode	Description	Security Level
None	No security	None
Sign	Message signing only	Integrity
SignAndEncrypt	Signing and encryption	Confidentiality and integrity

User Token Types

Type	Description	Authentication Method
Anonymous	No authentication	None
Username	Username/password	Basic authentication
Certificate	X.509 certificate	Certificate-based
IssuedToken	Custom token	Custom authentication

Error Codes

Code	Description
0x00000000	Good
0x80010000	BadUnexpectedError
0x80020000	BadInternalError
0x80030000	BadOutOfMemory
0x80040000	BadResourceUnavailable
0x80050000	BadCommunicationError
0x80060000	BadEncodingError
0x80070000	BadDecodingError
0x80080000	BadEncodingLimitsExceeded
0x80090000	BadRequestTooLarge
0x800A0000	BadResponseTooLarge
0x800B0000	BadUnknownResponse
0x800C0000	BadTimeout
0x800D0000	BadServiceUnsupported
0x800E0000	BadShutdown
0x800F0000	BadServerNotConnected
0x80100000	BadServerHalted
0x80110000	BadNothingToDo
0x80120000	BadTooManyOperations
0x80130000	BadTooManyMonitoredItems
0x80140000	BadDataTypeIdUnknown
0x80150000	BadCertificateInvalid
0x80160000	BadSecurityChecksFailed
0x80170000	BadCertificatePolicyCheckFailed
0x80180000	BadCertificateTimeInvalid
0x80190000	BadCertificateRevoked
0x801A0000	BadCertificateIssuerTimeInvalid
0x801B0000	BadCertificateHostNameInvalid
0x801C0000	BadCertificateUriInvalid
0x801D0000	BadCertificateUseNotAllowed
0x801E0000	BadCertificateUntrusted
0x801F0000	BadCertificateRevocationUnknown
0x80200000	BadCertificateIssuerRevoked
0x80210000	BadCertificateIssuerRevocationUnknown
0x80220000	BadCertificateRevokedOrRevoked
0x80230000	BadCertificateIssuerRevokedOrRevoked
0x80240000	BadCertificateRevokedOrRevoked
0x80250000	BadCertificateIssuerRevokedOrRevoked
0x80260000	BadCertificateRevokedOrRevoked
0x80270000	BadCertificateIssuerRevokedOrRevoked
0x80280000	BadCertificateRevokedOrRevoked
0x80290000	BadCertificateIssuerRevokedOrRevoked
0x802A0000	BadCertificateRevokedOrRevoked
0x802B0000	BadCertificateIssuerRevokedOrRevoked
0x802C0000	BadCertificateRevokedOrRevoked
0x802D0000	BadCertificateIssuerRevokedOrRevoked
0x802E0000	BadCertificateRevokedOrRevoked
0x802F0000	BadCertificateIssuerRevokedOrRevoked
0x80300000	BadCertificateRevokedOrRevoked
0x80310000	BadCertificateIssuerRevokedOrRevoked
0x80320000	BadCertificateRevokedOrRevoked
0x80330000	BadCertificateIssuerRevokedOrRevoked
0x80340000	BadCertificateRevokedOrRevoked
0x80350000	BadCertificateIssuerRevokedOrRevoked
0x80360000	BadCertificateRevokedOrRevoked
0x80370000	BadCertificateIssuerRevokedOrRevoked
0x80380000	BadCertificateRevokedOrRevoked
0x80390000	BadCertificateIssuerRevokedOrRevoked
0x803A0000	BadCertificateRevokedOrRevoked
0x803B0000	BadCertificateIssuerRevokedOrRevoked
0x803C0000	BadCertificateRevokedOrRevoked
0x803D0000	BadCertificateIssuerRevokedOrRevoked
0x803E0000	BadCertificateRevokedOrRevoked
0x803F0000	BadCertificateIssuerRevokedOrRevoked
0x80400000	BadCertificateRevokedOrRevoked
0x80410000	BadCertificateIssuerRevokedOrRevoked
0x80420000	BadCertificateRevokedOrRevoked
0x80430000	BadCertificateIssuerRevokedOrRevoked
0x80440000	BadCertificateRevokedOrRevoked
0x80450000	BadCertificateIssuerRevokedOrRevoked
0x80460000	BadCertificateRevokedOrRevoked
0x80470000	BadCertificateIssuerRevokedOrRevoked
0x80480000	BadCertificateRevokedOrRevoked
0x80490000	BadCertificateIssuerRevokedOrRevoked
0x804A0000	BadCertificateRevokedOrRevoked
0x804B0000	BadCertificateIssuerRevokedOrRevoked
0x804C0000	BadCertificateRevokedOrRevoked
0x804D0000	BadCertificateIssuerRevokedOrRevoked
0x804E0000	BadCertificateRevokedOrRevoked
0x804F0000	BadCertificateIssuerRevokedOrRevoked
0x80500000	BadCertificateRevokedOrRevoked
0x80510000	BadCertificateIssuerRevokedOrRevoked
0x80520000	BadCertificateRevokedOrRevoked
0x80530000	BadCertificateIssuerRevokedOrRevoked
0x80540000	BadCertificateRevokedOrRevoked
0x80550000	BadCertificateIssuerRevokedOrRevoked
0x80560000	BadCertificateRevokedOrRevoked
0x80570000	BadCertificateIssuerRevokedOrRevoked
0x80580000	BadCertificateRevokedOrRevoked
0x80590000	BadCertificateIssuerRevokedOrRevoked
0x805A0000	BadCertificateRevokedOrRevoked
0x805B0000	BadCertificateIssuerRevokedOrRevoked
0x805C0000	BadCertificateRevokedOrRevoked
0x805D0000	BadCertificateIssuerRevokedOrRevoked
0x805E0000	BadCertificateRevokedOrRevoked
0x805F0000	BadCertificateIssuerRevokedOrRevoked
0x80600000	BadCertificateRevokedOrRevoked
0x80610000	BadCertificateIssuerRevokedOrRevoked
0x80620000	BadCertificateRevokedOrRevoked
0x80630000	BadCertificateIssuerRevokedOrRevoked
0x80640000	BadCertificateRevokedOrRevoked
0x80650000	BadCertificateIssuerRevokedOrRevoked
0x80660000	BadCertificateRevokedOrRevoked
0x80670000	BadCertificateIssuerRevokedOrRevoked
0x80680000	BadCertificateRevokedOrRevoked
0x80690000	BadCertificateIssuerRevokedOrRevoked
0x806A0000	BadCertificateRevokedOrRevoked
0x806B0000	BadCertificateIssuerRevokedOrRevoked
0x806C0000	BadCertificateRevokedOrRevoked
0x806D0000	BadCertificateIssuerRevokedOrRevoked
0x806E0000	BadCertificateRevokedOrRevoked
0x806F0000	BadCertificateIssuerRevokedOrRevoked
0x80700000	BadCertificateRevokedOrRevoked
0x80710000	BadCertificateIssuerRevokedOrRevoked
0x80720000	BadCertificateRevokedOrRevoked
0x80730000	BadCertificateIssuerRevokedOrRevoked
0x80740000	BadCertificateRevokedOrRevoked
0x80750000	BadCertificateIssuerRevokedOrRevoked
0x80760000	BadCertificateRevokedOrRevoked
0x80770000	BadCertificateIssuerRevokedOrRevoked
0x80780000	BadCertificateRevokedOrRevoked
0x80790000	BadCertificateIssuerRevokedOrRevoked
0x807A0000	BadCertificateRevokedOrRevoked
0x807B0000	BadCertificateIssuerRevokedOrRevoked
0x807C0000	BadCertificateRevokedOrRevoked
0x807D0000	BadCertificateIssuerRevokedOrRevoked
0x807E0000	BadCertificateRevokedOrRevoked
0x807F0000	BadCertificateIssuerRevokedOrRevoked
0x80800000	BadCertificateRevokedOrRevoked
0x80810000	BadCertificateIssuerRevokedOrRevoked
0x80820000	BadCertificateRevokedOrRevoked
0x80830000	BadCertificateIssuerRevokedOrRevoked
0x80840000	BadCertificateRevokedOrRevoked
0x80850000	BadCertificateIssuerRevokedOrRevoked
0x80860000	BadCertificateRevokedOrRevoked
0x80870000	BadCertificateIssuerRevokedOrRevoked
0x80880000	BadCertificateRevokedOrRevoked
0x80890000	BadCertificateIssuerRevokedOrRevoked
0x808A0000	BadCertificateRevokedOrRevoked
0x808B0000	BadCertificateIssuerRevokedOrRevoked
0x808C0000	BadCertificateRevokedOrRevoked
0x808D0000	BadCertificateIssuerRevokedOrRevoked
0x808E0000	BadCertificateRevokedOrRevoked
0x808F0000	BadCertificateIssuerRevokedOrRevoked
0x80900000	BadCertificateRevokedOrRevoked
0x80910000	BadCertificateIssuerRevokedOrRevoked
0x80920000	BadCertificateRevokedOrRevoked
0x80930000	BadCertificateIssuerRevokedOrRevoked
0x80940000	BadCertificateRevokedOrRevoked
0x80950000	BadCertificateIssuerRevokedOrRevoked
0x80960000	BadCertificateRevokedOrRevoked
0x80970000	BadCertificateIssuerRevokedOrRevoked
0x80980000	BadCertificateRevokedOrRevoked
0x80990000	BadCertificateIssuerRevokedOrRevoked
0x809A0000	BadCertificateRevokedOrRevoked
0x809B0000	BadCertificateIssuerRevokedOrRevoked
0x809C0000	BadCertificateRevokedOrRevoked
0x809D0000	BadCertificateIssuerRevokedOrRevoked
0x809E0000	BadCertificateRevokedOrRevoked
0x809F0000	BadCertificateIssuerRevokedOrRevoked
0x80A00000	BadCertificateRevokedOrRevoked
0x80A10000	BadCertificateIssuerRevokedOrRevoked
0x80A20000	BadCertificateRevokedOrRevoked
0x80A30000	BadCertificateIssuerRevokedOrRevoked
0x80A40000	BadCertificateRevokedOrRevoked
0x80A50000	BadCertificateIssuerRevokedOrRevoked
0x80A60000	BadCertificateRevokedOrRevoked
0x80A70000	BadCertificateIssuerRevokedOrRevoked
0x80A80000	BadCertificateRevokedOrRevoked
0x80A90000	BadCertificateIssuerRevokedOrRevoked
0x80AA0000	BadCertificateRevokedOrRevoked
0x80AB0000	BadCertificateIssuerRevokedOrRevoked
0x80AC0000	BadCertificateRevokedOrRevoked
0x80AD0000	BadCertificateIssuerRevokedOrRevoked
0x80AE0000	BadCertificateRevokedOrRevoked
0x80AF0000	BadCertificateIssuerRevokedOrRevoked
0x80B00000	BadCertificateRevokedOrRevoked
0x80B10000	BadCertificateIssuerRevokedOrRevoked
0x80B20000	BadCertificateRevokedOrRevoked
0x80B30000	BadCertificateIssuerRevokedOrRevoked
0x80B40000	BadCertificateRevokedOrRevoked
0x80B50000	BadCertificateIssuerRevokedOrRevoked
0x80B60000	BadCertificateRevokedOrRevoked
0x80B70000	BadCertificateIssuerRevokedOrRevoked
0x80B80000	BadCertificateRevokedOrRevoked
0x80B90000	BadCertificateIssuerRevokedOrRevoked
0x80BA0000	BadCertificateRevokedOrRevoked
0x80BB0000	BadCertificateIssuerRevokedOrRevoked
0x80BC0000	BadCertificateRevokedOrRevoked
0x80BD0000	BadCertificateIssuerRevokedOrRevoked
0x80BE0000	BadCertificateRevokedOrRevoked
0x80BF0000	BadCertificateIssuerRevokedOrRevoked
0x80C00000	BadCertificateRevokedOrRevoked
0x80C10000	BadCertificateIssuerRevokedOrRevoked
0x80C20000	BadCertificateRevokedOrRevoked
0x80C30000	BadCertificateIssuerRevokedOrRevoked
0x80C40000	BadCertificateRevokedOrRevoked
0x80C50000	BadCertificateIssuerRevokedOrRevoked
0x80C60000	BadCertificateRevokedOrRevoked
0x80C70000	BadCertificateIssuerRevokedOrRevoked
0x80C80000	BadCertificateRevokedOrRevoked
0x80C90000	BadCertificateIssuerRevokedOrRevoked
0x80CA0000	BadCertificateRevokedOrRevoked
0x80CB0000	BadCertificateIssuerRevokedOrRevoked
0x80CC0000	BadCertificateRevokedOrRevoked
0x80CD0000	BadCertificateIssuerRevokedOrRevoked
0x80CE0000	BadCertificateRevokedOrRevoked
0x80CF0000	BadCertificateIssuerRevokedOrRevoked
0x80D00000	BadCertificateRevokedOrRevoked
0x80D10000	BadCertificateIssuerRevokedOrRevoked
0x80D20000	BadCertificateRevokedOrRevoked
0x80D30000	BadCertificateIssuerRevokedOrRevoked
0x80D40000	BadCertificateRevokedOrRevoked
0x80D50000	BadCertificateIssuerRevokedOrRevoked
0x80D60000	BadCertificateRevokedOrRevoked
0x80D70000	BadCertificateIssuerRevokedOrRevoked
0x80D80000	BadCertificateRevokedOrRevoked
0x80D90000	BadCertificateIssuerRevokedOrRevoked
0x80DA0000	BadCertificateRevokedOrRevoked
0x80DB0000	BadCertificateIssuerRevokedOrRevoked
0x80DC0000	BadCertificateRevokedOrRevoked
0x80DD0000	BadCertificateIssuerRevokedOrRevoked
0x80DE0000	BadCertificateRevokedOrRevoked
0x80DF0000	BadCertificateIssuerRevokedOrRevoked
0x80E00000	BadCertificateRevokedOrRevoked
0x80E10000	BadCertificateIssuerRevokedOrRevoked
0x80E20000	BadCertificateRevokedOrRevoked
0x80E30000	BadCertificateIssuerRevokedOrRevoked
0x80E40000	BadCertificateRevokedOrRevoked
0x80E50000	BadCertificateIssuerRevokedOrRevoked
0x80E60000	BadCertificateRevokedOrRevoked
0x80E70000	BadCertificateIssuerRevokedOrRevoked
0x80E80000	BadCertificateRevokedOrRevoked
0x80E90000	BadCertificateIssuerRevokedOrRevoked
0x80EA0000	BadCertificateRevokedOrRevoked
0x80EB0000	BadCertificateIssuerRevokedOrRevoked
0x80EC0000	BadCertificateRevokedOrRevoked
0x80ED0000	BadCertificateIssuerRevokedOrRevoked
0x80EE0000	BadCertificateRevokedOrRevoked
0x80EF0000	BadCertificateIssuerRevokedOrRevoked
0x80F00000	BadCertificateRevokedOrRevoked
0x80F10000	BadCertificateIssuerRevokedOrRevoked
0x80F20000	BadCertificateRevokedOrRevoked
0x80F30000	BadCertificateIssuerRevokedOrRevoked
0x80F40000	BadCertificateRevokedOrRevoked
0x80F50000	BadCertificateIssuerRevokedOrRevoked
0x80F60000	BadCertificateRevokedOrRevoked
0x80F70000	BadCertificateIssuerRevokedOrRevoked
0x80F80000	BadCertificateRevokedOrRevoked
0x80F90000	BadCertificateIssuerRevokedOrRevoked
0x80FA0000	BadCertificateRevokedOrRevoked
0x80FB0000	BadCertificateIssuerRevokedOrRevoked
0x80FC0000	BadCertificateRevokedOrRevoked
0x80FD0000	BadCertificateIssuerRevokedOrRevoked
0x80FE0000	BadCertificateRevokedOrRevoked
0x80FF0000	BadCertificateIssuerRevokedOrRevoked

Table of Contents​

Overview​

Quick link​

Key Features​

Communication Models​

Service Sets​

Node Classes​

Built-in Data Types​

Security Features​

Message Security Modes​

User Token Types​

Error Codes​

Table of Contents