OPC-UA Client¶

Characteristics¶

OPC (Open Platform Communications) enables access to machines, devices and other systems in a standardized way. To learn more about the standard visit the OPC-UA website.

Supported features¶

Data access
Events (e.g. Alarms)
Authentification

Information Model Requirements¶

The following Node Types can be used to model data structures:

Configuration¶

Connection settings¶

Property	Description	Example
OPC UA client application name	The name of the OPC UA client application.	demo
OPC UA client application URI	The URI of the OPC UA client application (auto-generated if not set).	(auto-generated)
OPC UA server IP address or hostname	The IP address or hostname of the OPC UA server.	192.168.138.71
OPC UA server TCP port	The TCP port of the OPC UA server.	4840
OPC UA server endpoint path	The endpoint path appended to opc.tcp://<host>:<port>/.	/
Client authentication method	The authentication method (Anonymous or UsernamePassword).	No authentication (anonymous access)
OPC UA security policy for the secure channel	The security policy applied to the secure channel.	No security
OPC UA message security mode	The message security mode (Auto, None, Sign, or SignAndEncrypt).	Automatic selection: prefer SignAndEncrypt > Sign > None
Request timeout in milliseconds	The timeout duration for client requests in milliseconds.	5000
Interval between reconnection attempts (Length)	The length of the interval between reconnection attempts.	3
Interval between reconnection attempts (Unit)	The unit of the interval between reconnection attempts.	Seconds
Maximum number of connection retries	The maximum number of connection retry attempts (0 = unlimited).	0
Client certificate keystore for OPC UA secure channel	The keystore containing client certificates for secure communication.	No client certificate keystore
Display format of OPC-UA NodeIds in Events	How node ids are handled for event filtering Node identifier as human-readable name string Node identifier in its standard OPC UA parsable format	Human-readable: `"Temperature Sensor 1"` Parsable format: `"ns=2;s=MyTemperatureSensor"`
Subscription Groups	Configuration of the subscription intervals (see Subscription Groups)

Subscription Groups

3 predefined subscription groups (default, slow and fast) can be used for subscribing to variable and event nodes.

Property	Description	Example
Publishing interval (Length)	Interval length for publishing data (in milliseconds)	1000 (Default), 10000 (Slow)
Publishing interval (Unit)	Time unit for publishing interval	Milliseconds
Sampling interval (Length)	Interval length for sampling data (in milliseconds)	500 (Default), 10000 (Slow)
Sampling interval (Unit)	Time unit for sampling interval	Milliseconds
Queue size	Size of the monitoring queue	1
Discard oldest	Whether to discard the oldest data when the queue is full	Checked (True)
Monitoring filter	Filter for monitoring specific data	None
Max number of monitored items	Maximum number of items that can be monitored	1000

Events (Alarms)¶

OPC UA Event Context Configuration

Property	Description	Example
Event source node ID	Node ID of the event source in OPC UA	"ns=0;i=2253" (server node ID)
Event subscription group	Group to which the event subscription belongs	"Default"
OPC UA event filter where clause	Filter condition for event subscription	"Severity >= 500"

Event variables

Supported event variables are "EventType" (String), "Severity" (String), "Message" (String) and "Time" (OffsetDateTime)

Property	Description	Example
Event source node ID	Node ID of the event source in OPC UA	"ns=0;i=2253"
Namespace index		`0`

Variables¶

Property	Description	Example
Node Id	Unique identifier for an OPC UA node, including namespace and path.	`ns=3;s="DB_Processing"."Module_A"."Pressure"`
Subscription	Defines the subscription type for monitoring node value changes.	`Default`, `Slow`, `Fast`
Log data	Enables logging of node data for debugging	(Enabled via checkbox)