OPC UA Servicescontain parameters that are conveyed between the Clientand the Server. The OPC UA Servicespecifications use tables to describe Serviceparameters, as shown in Table 1. Parameters are organized in this table into request parameters and response parameters.

Table 1– Service definition table

Name

Type

Description

Request

Defines the request parameters of the Service

Simple Parameter Name

Description of this parameter

Constructed Parameter Name

Description of the constructed parameter

Component Parameter Name

Description of the component parameter

Response

Defines the response parameters of the Service

The Name, Type and Description columns contain the name, data type and description of each parameter. All parameters are mandatory, although some may be unused under certain circumstances. The Description column specifies the value to be supplied when a parameter is unused.

Two types of parameters are defined in these tables, simple and constructed. Simple parameters have a simple data type, such as Booleanor String.

Constructed parameters are composed of two or more component parameters, which can be simple or constructed. Component parameter names are indented below the constructed parameter name.

The data types used in these tables may be base types, common types to multiple Servicesor Service-specific types. Base data types are defined in OPC 10000-3. The base types used in Servicesare listed in Table 2. Data types that are common to multiple Servicesare defined in Clause 7. Data types that are Service-specific are defined in the parameter table of the Service.

Table 2– Parameter Types defined in OPC 10000-3

Parameter Type

BaseDataType

Boolean

ByteString

Double

Duration

Guid

Int32

LocaleId

NodeId

QualifiedName

String

UInt16

UInt32

UInteger

UtcTime

XmlElement

The parameters of the Request and Indication service primitives are represented in Table 1as Request parameters. Likewise, the parameters of the Response and Confirmation service primitives are represented in Table 1as Response parameters. All request and response parameters are conveyed between the sender and receiver without change. Therefore, separate columns for request, indication, response and confirmation parameter values are not needed and have been intentionally omitted to improve readability.