How to Set Up OPC UA Alarm Notifications with SeQent

OPC Unified Architecture (OPC UA) is an open-standard, platform-independent protocol for industrial automation. OPC UA lets SeQent integrate with many manufacturing systems without requiring a system-specific gateway for each one, which is critical for multi-vendor facilities and brownfield deployments.

1. Compatible OPC UA Servers

SeQent has validated compatibility with:

• Kepware Server (formerly KEPServerEX), which supports 150+ industrial protocols
• CODESYS OPC UA server
• AVEVA Plant SCADA
• Ignition

If your system is not listed, contact SeQent support to verify compatibility.

2. Prerequisites and System Requirements

Before integration, ensure:

• The OPC UA server is installed, running, and network-accessible.
• The OPC UA server exposes the alarm or process value nodes you want to monitor (consult vendor documentation).
• The SeQent gateway server has network connectivity to the OPC UA server.
• Firewall rules permit TCP traffic on the OPC UA server’s endpoint port. The registered OPC UA port is 4840, but most servers use their own default. See the table below.
• Security settings are agreed on both sides (see below).

Default OPC UA endpoint ports

Ports are configurable. Always confirm the actual endpoint in the server’s configuration.

Security and authentication

OPC UA security has two separate layers, and both must match between the gateway and the server:

• Channel security: Security Mode None, Sign, or SignAndEncrypt, plus a security policy.
• User identity: Anonymous, username/password, or X.509 certificate, depending on what the OPC UA server requires.

Certificate trust: When Sign or SignAndEncrypt is used, the OPC UA server must trust the SeQent gateway’s application certificate, and the gateway must trust the server’s certificate. On first connection, the server typically places the gateway certificate in a rejected or pending list until an administrator trusts it. This is the most common cause of a failed first connection.

3. Identify OPC UA Servers and Nodes

Connect to your OPC UA server using a standalone OPC UA client such as UaExpert. Browse the server’s address space to identify the nodes you want to monitor, and document their node IDs. Example node ID: ns=2;s=Plant.Line1.Temperature_Alarm

4. Install the SeQent OPC UA Gateway

Download the SeQent OPC UA gateway from your admin portal. Run the installer on a server with network access to your OPC UA server. During setup, provide the OPC UA server endpoint URL, for example opc.tcp://192.168.1.10:49320 for a Kepware Server on its default port.

5. Subscribe to Nodes

In SeQent, go to Integrations > Data Sources > Add OPC UA Source. Enter the OPC UA server endpoint, security settings, and user credentials (if required). SeQent will connect and display available nodes. Select the nodes you want to monitor and subscribe to them.

6. Define Exception Conditions and Thresholds

For analog values (pressure, temperature, flow), define the conditions that trigger alerts. Examples:

• Temperature > 95°C → High alarm
• Pressure < 2.5 bar → Low alarm
• Flow rate variance > 15% → Deviation alarm

For discrete values (pump run/stop, valve open/closed), define state change rules. For example, any transition to “pump stopped” or “system offline” triggers an alert.

7. Map to Notification Rules

Route alarms based on their node properties:

• All temperature alarms → SMS to process technician
• Pressure and flow alarms → email to production engineer
• Pump/valve state changes → text to operator on-plant

8. Test and Validate

Trigger an alarm condition in your OPC UA source system, either by manually setting a sensor to an out-of-range value or by writing a test value with an OPC UA client. Verify the alarm appears in SeQent within 2 seconds and notifications reach all configured channels.

9. Multi-Vendor Plant Operations

OPC UA is particularly valuable in multi-vendor environments. A large automotive supplier might run different OPC UA servers in different areas of the plant, for example Kepware Server on one line, Ignition on another, and a CODESYS controller on a third. SeQent’s OPC UA gateway connects to each through its OPC UA endpoint, consolidating alarms into one unified escalation engine. This eliminates separate monitoring tools for each vendor and ensures consistent notification workflows across the facility.

10. Troubleshooting

Cannot connect to OPC UA server

• Verify the endpoint URL and port are correct and the server is running.
• Test connectivity from the gateway server with PowerShell: Test-NetConnection <server-host> -Port <port>. Ping alone is not reliable because ICMP is often blocked, and telnet is not installed by default on Windows Server.
• Check firewall rules on both servers and any network firewalls in between.
• Check certificate trust on both sides. If the server rejected the gateway certificate, move it to the trusted list in the server’s OPC UA configuration.
• Confirm the security mode and policy match a mode the server endpoint offers.
• If user authentication is enabled, verify the username and password.

Subscription fails or values not updating

• Verify the node IDs exist on the server by browsing with an OPC UA client.
• Confirm the server’s profile supports subscriptions. All servers listed in section 1 do; some minimal embedded servers do not.
• If node IDs are correct, check the server logs for subscription or session errors.

High latency or missed updates

• Review the subscription interval (default 1000 ms) in the OPC UA source configuration. A shorter interval improves responsiveness but increases load on both the OPC UA server and the gateway.
• Check network bandwidth and gateway server CPU usage. Sustained high CPU suggests the gateway is receiving more updates than it can process. Reduce the number of subscribed nodes, lengthen the interval for non-critical values, or add gateway server resources.

OPC UA integration lets your facility manage alarms across multiple automation vendors with a single, unified platform.