{"id":"a4050b6f-d8df-4d02-8417-ecfc7bcf9fec","task":"Diagnose ISO 15118 protocol-version mismatches between an EV and charge point using SDP and SupportedAppProtocol","domain":"iso.org","steps":["Capture the SECC Discovery Protocol (SDP) exchange first: the EV multicasts an SDP request, and the charge point's SECC responds with the TCP address/port and security option (TLS or not) the EV should connect to.","Once the TCP/TLS session is up, capture the SupportedAppProtocolReq from the EV, which lists the ISO 15118 schema versions/namespaces it supports (-2 vs -20) in priority order.","Charge point responds with SupportedAppProtocolRes selecting one mutually supported version and priority index, or a negotiation-failed status if there is no overlap.","If negotiation fails or falls back unexpectedly, check whether the charge point's firmware advertises -20 support at all — some hardware only implements -2 even though later documentation references -20 features like bidirectional power.","For bidirectional (V2X) or multi-contract Plug & Charge scenarios, confirm both sides negotiated -20 specifically before troubleshooting further up the stack, since a fallback to -2 silently removes those capabilities."],"gotchas":["A charge point and EV can both technically 'support ISO 15118' yet fail to negotiate a working session because they only share compatibility on paper — SDP/SupportedAppProtocol is where actual mutual version support is determined, and it's the first place to check, not the higher-level OCPP or vehicle logs.","ISO 15118-20 mandates TLS 1.3 while -2 environments commonly ran TLS 1.2 — a charge point upgraded to claim -20 support but still configured for TLS 1.2 will fail the security handshake in a way that looks like a version mismatch but is actually a TLS configuration gap.","Negotiation falling back to -2 silently disables -20-only features (bidirectional power, multiple Plug & Charge contracts) with no explicit error at the OCPP layer — a session can complete as a normal AC/DC charge while the intended V2X or multi-contract feature never activated."],"contributor":"waymark-seed","created":"2026-07-09T15:30:36.418Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/a4050b6f-d8df-4d02-8417-ecfc7bcf9fec"}