The OPC UA driver provides a secure, standards-compliant client for modern PLCs and SCADA gateways with automatic session recovery.
Connection Parameters
Basic Settings
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| EndpointUrl | string | Yes | - | OPC UA server URL (e.g., opc.tcp://10.0.0.5:4840) |
| PollingInterval | int | No | 1000 | Read cycle interval in milliseconds |
| ConnectTimeout | TimeSpan | No | 00:00:15 | Connection timeout |
| ReceiveTimeout | TimeSpan | No | 00:00:15 | Response timeout |
| SessionTimeout | TimeSpan | No | 01:00:00 | Session expiration (minimum 1 hour) |
| KeepAliveInterval | TimeSpan | No | 00:00:10 | Keep-alive ping interval |
Authentication
| Parameter | Type | Required | Description |
|---|---|---|---|
| Username | string | No | Username for authenticated connections |
| Password | string | No | Password for authenticated connections |
If Username and Password are not provided, the client connects using anonymous authentication.
Security Configuration
Security Mode
| Value | Description |
|---|---|
None | No security (default) |
Sign | Messages are signed but not encrypted |
SignAndEncrypt | Messages are signed and encrypted |
Security Policy
| Value | Algorithm |
|---|---|
None | No security |
Basic256Sha256 | SHA256 with RSA (recommended) |
Aes128_Sha256_RsaOaep | AES-128 with SHA256 |
Aes256_Sha256_RsaPss | AES-256 with SHA256 PSS |
Basic256 | Legacy SHA1 (deprecated) |
Basic128Rsa15 | Legacy RSA 1.5 (deprecated) |
Certificate Settings
| Parameter | Type | Description |
|---|---|---|
| CertificatePath | string | Path to client certificate (.pfx) |
| CertificatePassword | string | Password for client certificate |
| ServerCertificatePath | string | Path to server certificate (.der/.cer) to trust |
Node Addressing
Proxus supports all standard OPC UA Node ID formats.
Node ID Formats
| Format | Prefix | Example | Description |
|---|---|---|---|
| String | s= | ns=2;s=Device1.TagA | String identifier |
| Numeric | i= | ns=3;i=10024 | Numeric identifier |
| GUID | g= | ns=4;g=72962B91-... | GUID identifier |
| Opaque | b= | ns=5;b=QVVJ... | Base64-encoded opaque |
Namespace Index
The ns= prefix specifies the namespace index:
| Namespace | Description |
|---|---|
ns=0 | OPC UA standard namespace |
ns=1 | Server-specific namespace |
ns=2+ | Application namespaces |
Examples
ns=2;s=Channel1.Device1.Tag1 → String node in namespace 2
ns=2;s=PLC/Temperature → Hierarchical path
ns=3;i=1001 → Numeric node ID
ns=0;i=2259 → OPC UA Server Status nodeAdvanced Settings
Transport Quotas
| Parameter | Type | Default | Description |
|---|---|---|---|
| MaxStringLength | int | 65535 | Maximum string length |
| MaxArrayLength | int | 65535 | Maximum array length |
| MaxByteStringLength | int | 65535 | Maximum byte string length |
| MaxMessageSize | int | 4194304 | Maximum message size (4 MB) |
Application Identity
| Parameter | Type | Description |
|---|---|---|
| ApplicationName | string | Client application name |
| ApplicationUri | string | Application URI (auto-generated if not set) |
| ProductUri | string | Product URI |
Data Types
| Proxus Type | OPC UA Type | Description |
|---|---|---|
| Bool | Boolean | True/False |
| Short | Int16 | Signed 16-bit |
| UShort | UInt16 | Unsigned 16-bit |
| Int | Int32 | Signed 32-bit |
| UInt | UInt32 | Unsigned 32-bit |
| Long | Int64 | Signed 64-bit |
| ULong | UInt64 | Unsigned 64-bit |
| Float | Float | 32-bit IEEE 754 |
| Double | Double | 64-bit IEEE 754 |
| String | String | UTF-8 string |
Performance Features
Automatic Session Recovery
If the network drops or the server restarts, the driver handles reconnection automatically:
- Recreates sessions transparently
- Re-establishes subscriptions
- No manual intervention required
- Up to 5 internal retries before reporting errors
Batch Reading
Multiple tag reads are grouped into a single ReadRequest, reducing network round-trips significantly.
Node ID Caching
Parsed Node IDs are cached to avoid repeated parsing overhead.
Troubleshooting
| BadCertificateUntrusted | Certificate not trusted | Move client certificate to Trusted folder on Server | | BadUserAccessDenied | Invalid credentials | Verify Username/Password for the endpoint | | BadNodeIdUnknown | Typo in Node ID | Copy Node ID directly from UaExpert or server GUI |
For Node ID format help, see OPC UA Address Syntax. For common OPC UA errors, see OPC UA Errors.
Official Resources
- OPC Foundation: OPC UA Online Reference
- OPC Foundation: OPC UA Specifications