Connect to an OPC UA server

Connect to an OPC UA server using Synnax.

The Synnax Driver connects to any OPC UA server: PLCs, SCADA systems, DCS, MES, and industrial sensors. Secure and non-secure connections are supported with anonymous, username and password, or certificate authentication.

Prerequisites

Before you can connect to an OPC UA server, you will need to ensure that you have the following:

A Synnax Core running on your network.
A Synnax Driver running on your network. This Driver must be connected to the Core and running on the same machine or network as your OPC UA server.
The Synnax Console installed on your local machine.
An OPC UA server running on your network. This server must be reachable by the Driver.

Supported operating systems

Table

Platform	Status
Windows	✓ Supported
Linux	✓ Supported
NI Linux Real-Time	✓ Supported
macOS	✓ Supported
Docker	✓ Supported

When running in a Docker container, ensure the container has network access to the OPC UA server.

Common OPC UA servers

Table

Server	Description
open62541	Open-source OPC UA stack
Beckhoff TwinCAT	PLC and automation platform
FactoryTalk	Allen-Bradley FactoryTalk with OPC UA
Ignition	SCADA platform with built-in OPC UA server
Siemens S7	PLCs with OPC UA support
Prosys OPC UA Simulation Server	For testing and development

Configuration parameters reference

Table

Parameter	Type	Required	Default	Description
`name`	string	Yes	-	Human-readable server name for identification in Console
`rack`	string	Yes	-	Synnax Driver (rack) key that will connect to the OPC UA server
`endpoint`	string	Yes	-	Server endpoint URL (e.g., `opc.tcp://localhost:4840`)
`username`	string	No	-	Username for server authentication (optional)
`password`	string	No	-	Password for server authentication (optional)
`security_mode`	string	No	`None`	Security mode: `None`, `Sign`, or `SignAndEncrypt`
`security_policy`	string	No	`None`	Security policy: `None`, `Basic128Rsa15`, `Basic256`, `Basic256Sha256`, `Aes128_Sha256_RsaOaep`, `Aes256_Sha256_RsaPss`
`client_cert`	string	No	-	Client certificate for signing/encrypting (required if security policy ≠ `None`)
`client_private_key`	string	No	-	Client private key for signing/encrypting (required if security policy ≠ `None`)
`server_cert`	string	No	-	Trusted server certificate (required if security policy ≠ `None`)

Security Mode & Policy Reference

Security Mode:

None -> No security applied
Sign -> Messages are signed but not encrypted. Provides authentication without confidentiality
SignAndEncrypt -> Messages are signed and encrypted for full authenticity and confidentiality

Security Policy:

None -> No encryption
Basic128Rsa15 -> 128-bit encryption with RSA-15
Basic256 -> 256-bit encryption
Basic256Sha256 -> 256-bit encryption with SHA-256
Aes128_Sha256_RsaOaep -> 128-bit AES with SHA-256 and RSA OAEP
Aes256_Sha256_RsaPss -> 256-bit AES with SHA-256 and RSA PSS

How-to

Console

Python

Connect to OPC UA Server

import synnax as sy
from synnax import opcua

# Initialize Synnax client
client = sy.Synnax()

# Retrieve the embedded rack
rack = client.racks.retrieve_embedded_rack()

# Create the OPC UA device
device = opcua.Device(
    endpoint="opc.tcp://localhost:4841/",
    name="My OPC UA Server",
    location="opc.tcp://localhost:4841/",
    rack=rack.key,
)

# Create the device in Synnax
device = client.devices.create(device)

# Or retrieve by location
device = client.devices.retrieve(location="opc.tcp://localhost:4841/")

# Or retrieve by name
device = client.devices.retrieve(name="My OPC UA Server")

print(f"Connected to OPC UA server: {device.name}")

Disconnect server

import synnax as sy

# Initialize Synnax client
client = sy.Synnax()

# Retrieve the device by name
device = client.devices.retrieve(
    name="My OPC UA Server",
    ignore_not_found=True
)

if device is not None:
    # Delete the server
    client.devices.delete([device.key])
    print(f"Disconnected OPC UA server: {device.name}")
else:
    print("Server not found")

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