OPC UA

OPC Unified Architecture (OPC UA) is a platform-independent, service-oriented architecture that integrates diverse industrial automation systems. It provides a robust, secure, and scalable framework for connecting devices and transmitting data across various platforms. OPC UA's ability to standardise communication and ensure interoperability makes it an essential protocol connector in modern industrial environments.

Here is a practical example of how OPC UA can be used as a protocol in factory automation:

• An OPC UA server is installed on a central controller.

• Various production machines, equipped with OPC UA-enabled sensors and actuators, connect to the server.

• A manufacturing execution system (MES) acting as an OPC UA client retrieves machine statuses and production data for real-time monitoring and control. The OPC UA client in our case can be a machine with an edge-connector on it.

Functions

create

Constructs an OPC UA client instance.

Parameter	Type	Default	Description
securityMode		'None'	One from 'unauthorized', 'None', 'Sign' or 'SignAndEncrypt'.
securityPolicy		'None'	One from 'Aes128_Sha256_RsaOaep', 'Basic128', 'Basic192', 'Basic192Rsa15', 'Basic256Sha256', 'Basic256Rsa15', 'Basic256Rsa15', 'unauthorized', 'None', 'PubSub_Aes128_CTR' or 'PubSub_Aes256_CTR'.
certificateFile	String
privateKeyFile	String

listenToEvents

Reports about relevant events. You can use the listener box to connect a function to run on events.

connect

Connects to an OPC UA server.

Parameter	Type	Description
endpointUrl	String
userIdentity	Object	Object that contains user identity information. All following parameters must be part of this object if utilised.
userIdentity. username	String
userIdentity. password	String
userIdentity. userCertificate	String
userIdentity. userCertificate PrivateKey	String

disconnect

browse

Detailed browsing of the given browse path (non-recursive).

You can use the parameter address to navigate to the desired folder. The function shows the contents of the root folder as default. You can also specify the session with sessionId.

readNode

Reads a variable.

Use parameter address for the node ID or a valid browse path. You can also specify the session with sessionId.

readVariableValue

Reads the value of a variable.

Use parameter address for the node ID or a valid browse path. You can also specify the session with sessionId.

monitorNode

Starts monitoring an item.

Parameter	Type	Default	Description
address	String		Node ID or a valid browse path.
listener	Function		The connected function is automatically called upon time change.
options	Object		The options object can contain all the following parameters.
options. sampling Interval	Integer	1000	The sampling interval in milliseconds.
options. queueSize	Integer	100	The maximum queue size.
options. discard Oldest	Boolean	true	Sets the policy for when the queue is full. Decides whether to discard the oldest or newest entries. Default discards the oldest entries.
options. subscriptionId	String

monitorValue

Starts monitoring an item value.

Parameter	Type	Default	Description
address	String		Node ID or a valid browse path.
listener	Function		The connected function is automatically called upon time change.
options	Object		The options object can contain all the following parameters.
options. sampling Interval	Integer	1000	The sampling interval in milliseconds.
options. queueSize	Integer	100	The maximum queue size.
options. discard Oldest	Boolean	true	Sets the policy for when the queue is full. Decides whether to discard the oldest or newest entries. Default discards the oldest entries.
options. subscriptionId	String

stopMonitor

Stops monitoring an item. Use the parameter nodeId to specify what to stop monitoring.

writeNode

Does nothing at the moment.

createSession

Creates a session.

closeSession

Closes the session and all associated subscriptions. Use the parameter sessionId to specify which session to close.

createSubscription

Creates a subscription.

Parameter	Type	Default	Description
sessionId	String
options	Object
options. maxNotifications PerPublish	Integer	0	The maximum amount of notifications per time publishing.
options. priority	Integer		The subscription priority from 0 to 255
options. publishing Enabled	Boolean	true	Enable or disable publishing.
options. requestedLifetime Count	Integer
options. requestedMax KeepAliveCount	Integer	10
options. requested PublishingInterval	Integer	1000	Interval in milliseconds for publishing.