General Settings
The General Settings tab is where you configure the server's network identity, performance, and identification URIs. It is the first tab shown after you create an OPC-UA server entry, and it is divided into four labelled sections: Server Configuration, Application Identity, Timing Configuration, and Namespace Configuration.
All fields commit on blur. Type a value and click outside the field (or press Tab) to save it.
Server Configuration
This section controls whether the server runs and where it listens.
| Field | Type | Default | Description |
|---|---|---|---|
| Enable Server | Toggle | Off | Switches the OPC-UA plugin on or off at runtime. The helper text reads Server is disabled when off and Server will start when PLC runs when on. Leave off until the rest of the configuration is complete. |
| Server Name | Text | OpenPLC OPC UA Server (placeholder) | Human-readable name advertised to clients during discovery. Pick something operators will recognise (for example, Plant Floor PLC). |
| Network Interface | Dropdown | All Interfaces (0.0.0.0) | Selects the IP address the server binds to. Choose Localhost (127.0.0.1) to restrict access to the host running the runtime, or All Interfaces (0.0.0.0) to accept connections on every network the device is connected to. |
| Port | Number | 4840 | TCP port for incoming OPC-UA connections. Range: 1–65535. The OPC-UA standard reserves 4840. The label includes the inline hint Default: 4840. |
| Endpoint Path | Text | /openplc/opcua (placeholder) | Path appended to the endpoint URL. Some clients require an explicit path; an empty value is also accepted. |
The full endpoint URL clients use to connect is:
codeopc.tcp://<host>:<port><endpoint_path>
For example, with the placeholder endpoint path on a device reachable at 192.168.1.50:
codeopc.tcp://192.168.1.50:4840/openplc/opcua
Application Identity
These two URIs identify the server to clients. The defaults are placeholders the editor inserts when you create the server. You can keep them as-is for development, or replace them with values that match your organisation's URN scheme.
| Field | Type | Default | Description |
|---|---|---|---|
| Application URI | Text | urn:openplc:opcua:server (placeholder) | Globally unique URI for this server instance. If you use custom certificates, the certificate's Subject Alternative Name must match this value. |
| Product URI | Text | urn:openplc:runtime (placeholder) | URI identifying the product family. Usually shared across all OPC-UA servers in the same fleet. |
The on-screen helper text reads: "Configure the OPC-UA application identity URIs. These are used by clients to identify the server."
Timing Configuration
This section sets how often the OPC-UA server refreshes the values it publishes from the running PLC program.
| Field | Type | Default | Description |
|---|---|---|---|
| Cycle Time (ms) | Number | 100 | Update frequency in milliseconds. Range: 10–10000. The inline hint reads Update frequency for OPC-UA variables (10-10000ms). |
Lower values give clients fresher data at the cost of more CPU on the runtime. The default of 100 ms is a balanced starting point. If your client only needs slow trending (one update per second), increase the cycle time to reduce load.
Namespace Configuration
The OPC-UA address space is partitioned into namespaces. All variables you expose live inside the namespace identified by the URI shown here.
| Field | Type | Default | Description |
|---|---|---|---|
| Namespace URI | Text (read-only on this tab) | urn:openplc:opcua:namespace | URI for the namespace that holds your exposed variables. The same field is editable on the Address Space tab. |
The on-screen helper text reads: "The namespace URI for OpenPLC variables in the OPC-UA address space."
What's Next?
- Security Profiles: set the encryption and authentication options clients are allowed to use.
- Users: add user accounts that can authenticate against the server.
- Address Space: choose which PLC variables to expose.
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