Safety-critical embedded systems increasingly depend on modular communication architectures integrating heterogeneous network protocols within constrained, high-integrity environments. This paper presents a structured investigation of network protocol integration within a SIL-4 Safe Onboard Platform (SOP), focusing on an Embedded Communication Module (ECM) that simultaneously supports five protocol stacks including TLS 1.2. A three-tier automated verification framework is proposed and applied, utilizing four independent data sources: boot logs, application traces, Wireshark packet captures, and formal VerfAz verification reports. Integration complexities IC1-IC4 are identified and mitigated. Empirical results confirm all five KPI thresholds: TLS handshake <=200 ms, RTT=24 ms (52% margin), throughput=2.4 Mbps (140% excess), CPU=18% (28% margin), and 100% message delivery. A critical safety finding -- TLS session termination via SIGKILL -- is identified and escalated. The existing safety plan is evaluated against EN 50128:2011+A1:2020 and IEC 61508-3, revealing four gaps (G1-G4) with five enhancement recommendations.

Network Protocol Integration, ECM, Automated Verification, TLS 1.2, Safety-Critical Systems