Can OPC Expert be used to troubleshoot OPC UA certificate exchange and trust relationship issues?
Troubleshooting OPC UA Certificate Exchange and Trust Issues
OPC Expert supports OPC UA security profiles and can be used directly to test, diagnose, and resolve certificate exchange and trust issues between OPC UA clients and servers. When a secure OPC UA connection fails due to a certificate problem, OPC Expert produces a verbose error description that identifies the nature of the failure, whether it is an untrusted certificate, an expired certificate, a hostname mismatch, or a rejected security policy.
Testing OPC UA Security Configurations
Within OPC Expert’s connection interface, you can choose among available OPC UA security modes and policies when connecting to a server. This includes None, Sign, and SignAndEncrypt modes, as well as specific security policy options. The ability to test each combination independently means you can isolate whether a connection succeeds under one security profile and fails under another, which narrows the problem to the specific security configuration rather than requiring you to guess where the mismatch lies.
Certificate Trust Workflows
OPC UA requires that both the server and client explicitly trust each other’s certificates. When a client presents a certificate the server does not trust, or vice versa, the connection is rejected. OPC Expert surfaces this condition with a clear error description rather than a generic failure message. The diagnostic output identifies whether the rejection came from the server side or the client side and what the specific trust condition was, giving the engineer the precise information needed to add the certificate to the appropriate trust store.
Security Certificates and Write Operations
Security certificates are required for OPC UA connections that use Sign or SignAndEncrypt security modes, and those security modes apply to all operations over that connection including reads, writes, and browsing. A connection using the None security mode does not require certificate exchange, but that mode is typically restricted or disabled by server policy in secure environments. Whether write operations specifically require certificates depends on the security policy the OPC UA server is configured to enforce, not on the nature of the write operation itself.
Relevant Tools
OPC Expert (OPC Viewer): The primary tool for testing OPC UA connection parameters, including security mode and certificate configuration, with verbose feedback on each connection attempt.
OPC Expert (Troubleshooting OPC and DCOM): Provides additional diagnostic context when certificate issues are intertwined with DCOM or network-layer problems in mixed Classic and UA environments.
OPC Expert’s ability to test individual security configurations and surface certificate-specific error information makes it a practical first step when diagnosing OPC UA trust relationship failures before making changes to certificate stores or server security policies.