Initialization sequence

The

FactoryTalk Linx

OPC

UA Connector

dialog box adds the new

FactoryTalk Linx

OPC

UA Connector and/or

OPC

UA Servers to the

FactoryTalk Directory

. The

FactoryTalk Directory

stores all configured settings on its host and replicates the settings to client

FactoryTalk Services Platform

instances.

The

FactoryTalk Linx

OPC

UA Connector

dialog box creates a

FactoryTalk

client session and attempts to connect to the

FactoryTalk Linx

OPC

UA Connector service on the workstation defined in

FactoryTalk Linx

OPC

UA Connector > Connector Settings > Computer hosting the

FactoryTalk Linx

OPC

UA Connector

.

If the

FactoryTalk Linx

OPC

UA Connector service is not running on the target workstation, the

FactoryTalk Services Platform

instance on the target workstation starts the

FactoryTalk Linx

OPC

UA Connector service.

Read the

@DP_ServiceStartupTimestamp

predefined diagnostic item to determine when the

FactoryTalk Linx

OPC

UA Connector service was started.

The

FactoryTalk Linx

OPC

UA Connector service reads the new configuration settings replicated from the

FactoryTalk Directory

host.

FactoryTalk Services Platform

notifies the

FactoryTalk Linx

OPC

UA Connector service a new

FactoryTalk

client wants to open an

OPC

UA session.

Read the

@DAQ_ClientConnectionsQty

predefined diagnostic item to determine the number of active

FactoryTalk

client sessions.

The

FactoryTalk Linx

OPC

UA Connector service determines if the requested

OPC

UA Server connection exists.

If the server connection exists, the

FactoryTalk Linx

OPC

UA Connector service adds the

FactoryTalk Linx

OPC

UA Connector

dialog box to the existing connection.

If the server connection does not exist, the

FactoryTalk Linx

OPC

UA Connector initializes a new server connection.

Read the

@DAQtoOPC_ContainersQty

predefined diagnostic item to determine the number of active

OPC

UA server sessions.

The

FactoryTalk Linx

OPC

UA Connector service loads its namespace cache file from disk, if available.

Read the

@OPC_NamespaceCacheIsPresentStatus

predefined diagnostic item to determine if the

FactoryTalk Linx

OPC

UA Connector service has a namespace cache file for a specific

OPC

UA Server.

The

FactoryTalk Linx

OPC

UA Connector service attempts to connect to the

OPC

UA Servers defined in

FactoryTalk Linx

OPC

UA Connector > OPC UA Servers > Endpoint URL

.

If a security policy was selected, the

FactoryTalk Linx

OPC

UA Connector will provide its certificate to the remote OPC UA Server. The OPC UA server must accept the certificate, which may be a manual process, if it is the first time the certificate was received.

Next, the OPC UA Server will send its certificate to the

FactoryTalk Linx

OPC

UA Connector. In a default configuration,

FactoryTalk Linx

OPC

UA Connector automatically accepts incoming certificates. If certificates are not accepted automatically, you must manually accept incoming certificates using the

Certificate Management

tab of the

FactoryTalk Linx

OPC

UA Connector.

Certificate Management

tasks must be performed locally on the OPC UA Server.

If authentication is configured, the

FactoryTalk Linx

OPC

UA Connector will pass the username and password configured for the endpoint to the UA Server. After authentication succeeds, the connection is completed.

Read the

@OPC_CommConnectedStatus

predefined diagnostic item to determine the success or failure of a connection to an

OPC

UA Server.

The

FactoryTalk Linx

OPC

UA Connector service compares namespace indexes from its cache file against the namespace indexes provided by the

OPC

UA Server.

If the namespace indexes do not match or the cache file does not exist, the

FactoryTalk Linx

OPC

UA Connector uploads the namespace from the

OPC

UA Server.

Read the

@OPC_NamespaceCacheUploadCompleteStatus

predefined diagnostic counter to determine when the namespace upload is complete.

When the connection to the

OPC

UA Server is established and the namespace is either confirmed or a namespace upload is complete, the

FactoryTalk Linx

OPC

UA Connector service provides diagnostic nodes for the

OPC

UA Server.

Open

FactoryTalk Linx

OPC

UA Connector > OPC UA Servers

and

FactoryTalk Linx

OPC

UA Connector > Real-Time Diagnostics

to view real-time diagnostic values.

The

FactoryTalk Linx

OPC

UA Connector then uploads current

DataType

information below the Server’s

Root/Types/DataTypes

Node and merges custom type and subtype information with OPC-defined

DataTypes

.

The initialization sequence is complete. As

FactoryTalk

clients request tag values, the

FactoryTalk Linx

OPC

UA Connector subscribes to and reads node values from the

OPC

UA Server, providing them back to the

FactoryTalk

clients as tags.

The

OPC

UA Server monitors item values at the specified update rate and pushes update notifications to the

OPC

UA Connector as the value or the quality changes. The

FactoryTalk Linx

OPC

UA Connector stores the last value and quality that it receives. If neither has changed, there is no traffic on the network other than heartbeat notifications. If a Live Data client issues a direct read request that the

FactoryTalk Linx

OPC

UA Connector does not query the

OPC

UA Server, instead, it returns the cached value and quality. This ensures that direct reads are kept in sync with pushed update notifications from the

OPC

UA Server.