OPC UA Services Supported by Fernhill SCADA

Help Contents

Introduction

The OPC UA Server in Fernhill SCADA supports these service sets:

Discovery Service Set

The Discovery Service Set allows an OPC UA Client to discover information about an OPC UA implementation. Fernhill SCADA supports these discovery services:

ServiceDescription
FindServers Returns the servers known to the Fernhill SCADA Server.
GetEndpoints Returns the end points supported by the Fernhill SCADA Server.

Secure Channel Service Set

The Secure Channel Service Set allows an OPC UA Client to set up a secure communication channel to an OPC UA Server. Fernhill SCADA supports these secure channel services:

ServiceDescription
OpenSecureChannel Opens or renews a secure channel to an OPC UA Server.

Fernhill SCADA supports these security policies:

  • None
  • Basic128Rsa15 (see note)
  • Basic256 (see note)
  • Basic256Sha256
  • Aes128_Sha256_RsaOaep
  • Aes256_Sha256_RsaPss
CloseSecureChannel Terminates a secure channel.

Note: Security policies Basic128Rsa15 and Basic256 are deprecated and not enabled by default. To enable these policies use the OpcUAServerWeakSecurity option in the SCADA Server Parameters.

Session Service Set

The Session Service Set allows an OPC UA Client to set up an application layer communication channel to an OPC UA Server. The application layer includes user credentials to identity the user to the OPC UA Server. Fernhill SCADA supports these Session services:

ServiceDescription
CreateSession Creates a session on an OPC UA Server.
ActivateSession Makes the session active with a User Identity Token.
CloseSession Closes the current session.

The ActivateSession service supports these User Identity Tokens:

Identity TokenRemarks
Anonymous Anonymous login is supported if the Guest account is enabled in the SCADA Server. The Guest account is enabled in one of two ways:
Username The username and password are checked using the operating system running the SCADA Server.
X509 The client provides an X509 Certificate. To be accepted:
  • The X509 Certificate must be in the Trusted Certificate List of the SCADA Server.
  • The Subject Common Name of the X509 Certificate must be a valid Username in the operating system running the SCADA Server.

Note: Anonymous login is only supported if the Guest account is enabled in the SCADA Server. The Guest account is enabled in one of two ways:

View Service Set

The View Service Set allows an OPC UA Client to discover the nodes in an OPC UA Server. Fernhill SCADA supports these View services:

ServiceDescription
Browse Discover the nodes in a server.
BrowseNext Continues a browse request.
TranslateBrowsePathsToNodeIds Translates a browse path into a node id.
RegisterNodes Defines which nodes a client will access often.
UnregisterNodes Removes nodes from the list of nodes the client will access often.

Attribute Service Set

The Attribute Service Set allows an OPC UA Client to access the attributes of nodes in an OPC UA Server. Fernhill SCADA supports these Attribute services:

ServiceDescription
Read Reads the attributes of a node.
HistoryRead Reads historical data of a node.
Fernhill SCADA supports these HistoryReadDetails parameters:
  • ReadRawModifiedDetails
  • ReadProcessedDetails
  • ReadAtTimeDetails
Write Writes the attributes of a node.

Method Service Set

The Method Service Set allows an OPC UA Client to access the methods of nodes in an OPC UA Server. In Fernhill SCADA methods call Tag Commands. Fernhill SCADA supports these Method services:

ServiceDescription
Call Calls a method on a node.

Subscription Service Set

The Subscription Service Set allows an OPC UA Client to manage subscriptions on an OPC UA Server. A Subscription is a collection of Monitored Items which can be read as a group. Fernhill SCADA supports these Subscription services:

ServiceDescription
CreateSubscription Creates a Subscription.
ModifySubscription Changes the parameters of an existing Subscription.
Publish Asks the server to respond with updates from the Subscription.
SetPublishingMode Changes the publishing mode of a Subscription.
DeleteSubscriptions Deletes 1 or more Subscriptions.

Monitored Item Service Set

The Monitored Item Service Set allows an OPC UA Client to manage the items in a Subscription. Fernhill SCADA supports these Monitored Item services:

ServiceDescription
CreateMonitoredItems Adds items to a Subscription.
DeleteMonitoredItems Removes items from a Subscription.
ModifyMonitoredItems Changes the parameters of items in a Subscription.
SetMonitoringMode Changes how the item is reported.

Further Information

Enable the OPC UA Server

To find out how to enable the OPC UA Server in Fernhill SCADA.

Diagnosing Connection Problems

To learn how to solve problems connecting to a Fernhill SCADA Server.

opcfoundation.org

For information about OPC standards.

Glossary

For the meaning of terms used in Fernhill SCADA.