# Device settings
Some technology-specific fields are essential for the agent when setting up an OPC UA device (also named as OPC UA server) in the IoTHub.
# Thing
A thing is a digital representation of a physical device (commonly termed "digital-twin").
# Configuration
The configuration defines connection-related settings for communicating with the device. Here, essential technology-specific fields to set are:
endpoint: The endpoint defines the devices address and listening port number. This information is used by the agent for establishing a connection with the OPC UA server.securityMethod: This field defines the security method for discovering a specific endpoint in the OPC UA server. Here, valid security methods are:
| Security method | Description |
|---|---|
| None | No security method |
| Sign | Signed message exchange |
| Sign&Encrypt | Signed and encrypted message exchange |
securityPolicy: This field defines the security policy for discovering a specific endpoint in the OPC UA server. Here, valid security policies are:
| Security policy | Reference |
|---|---|
| None | http://opcfoundation.org/UA/SecurityPolicy#None |
| Basic256Sha256 | http://opcfoundation.org/UA/SecurityPolicy#Basic256Sha256 |
| Basic256 | http://opcfoundation.org/UA/SecurityPolicy#Basic256 |
| Basic128Rsa15 | http://opcfoundation.org/UA/SecurityPolicy#Basic128Rsa15 |
# Attributes
The attributes define settings that do not directly affect the connection between agent-device but are still relevant for communication. Here, essential technology-specific fields are:
sampling_interval: The sampling interval defines a "best-effort" cyclic rate that the agent uses to sample data from the device. "Best-effort" in this context means that the agent does its best to sample data at the given time frame.
# Properties
Properties represent all items that the agent should monitor; this means reading or writing data from or into them, respectively.
# Attributes
Each property contains the following technology-specific fields:
namespace: Namespace index authority of the node.identifier_type: Type of the node's identification. HEre, valid identifier types are:
| Identifier type | OPC UA notation | Used for |
|---|---|---|
| String | s= | String identifiers |
| Numeric | i= | Numeric identifiers |
| Guid | g= | GUID or UUID identifiers |
| Opaque | b= | Base64 encoded identifiers |
identifier: Identification of the node. Depending on the identifier type, it can be a string, number, guid, or a base64string.
# Actions
Actions are interaction affordances that allow to invoke specific functions on the device or retrieve information from it. Here, essential technology-specific actions are:
connect: Use this action for connecting and subscribing to the OPC UA device.disconnect: Use this action for disconnecting and unsubscribing from the OPC UA device.