OPC-UA Integrator / Developer

OPC UA Developer — Embedded Server Integration (S2OPC / open62541) We are looking for an experienced OPC UA developer to support the integration and hardening of an OPC UA server stack on resource-constrained embedded devices (Linux-based and RTOS targets). The role focuses on high-level SCADA configuration. This is a low-volume, advisory engagement — approximately 3 hours per week, ongoing. We are looking for a senior expert who can answer specific, technical questions, review architecture decisions, and unblock implementation problems. Not a full-time implementation role. Required experience: - Solid grasp of OPC UA Part 4 (Services), Part 6 (Mappings), Part 7 (Profiles) and especially part 12 (Discovery & GDS) including the Push model for certificate management - OPC UA SecureChannel internals — understanding that this is not TLS, including SecurityPolicies (Basic256Sha256, Aes128Sha256RsaOaep, Aes256Sha256RsaPss) and MessageSecurityModes - PKI / X.509 handling in an OPC UA context: ApplicationGroup, HttpsGroup, UserTokenGroup, trust lists, CRLs, and the `UpdateCertificate` / `UpdateTrustList` methods - Information modeling: deriving custom ObjectTypes, working with NodeSet2.xml, namespace handling - Alarms & Conditions (Part 9) and Historical Access (Part 11) if relevant to your background Nice to have: - Experience with Companion Specifications (DI 10000-100, ADI, PA-DIM, or domain-specific) - IDevID / secure provisioning, manufacturer-installed certificates - GDS implementations (EJBCA, Unified Automation UaGds, Siemens UA Certificate Manager) - Modbus-to-OPC-UA gateway design About the work: - Modeling OPC-UA XML Models with SiOME - Codebase is C, embedded Linux, with strict memory and footprint constraints - Cryptographic backend: mbedTLS - Remote, async-friendly. Format is typically: written questions with code snippets, occasional 30–60 min calls for deeper architecture discussions To apply, please include: 1. Which OPC UA stack(s) you have shipped to production and in what role 2. A concrete example of an information model you designed or extended 3. Your approach to certificate lifecycle in a fleet of embedded devices Generic "I know OPC UA" applications will be skipped — please be specific.