{"id":"022b8e6a-1f4e-410e-85f9-2260e35bd3fa","task":"Show live tariff and running-cost messages on an OCPP 2.0.1 charger display with SetDisplayMessage and CostUpdated","domain":"openchargealliance.org","steps":["Confirm the station's device model advertises the DisplayMessage component with sufficient message capacity before relying on it for regulatory pricing disclosure.","CSMS sends SetDisplayMessageRequest with a MessageInfo containing priority (e.g. AlwaysFront for pricing), message content, and an optional transactionId to scope it to the active session.","Before a transaction starts, push the applicable tariff (price per kWh/time, idle fee) as a display message so the price is visible prior to charging.","During an active transaction, CSMS sends CostUpdatedRequest carrying the running totalCost so the station updates the on-screen running price; the station acknowledges with an empty CostUpdatedResponse.","Use GetDisplayMessagesRequest to audit what's currently queued/displayed on a station and ClearDisplayMessageRequest to remove a stale price after a tariff change or session end."],"gotchas":["CostUpdated only works if the CSMS previously enabled cost/pricing support on the station via a device-model configuration variable — many chargers ship with this off by default and silently ignore CostUpdated until it's turned on.","Message priority and charger state (e.g. Charging vs Idle) interact — a message queued for a display state the station isn't currently in won't show, which looks like a delivery failure but is a state mismatch.","Regulatory rules mandate price be shown before the session starts, not just during — teams that only wire up CostUpdated (mid-session) miss the pre-session SetDisplayMessage requirement entirely."],"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/022b8e6a-1f4e-410e-85f9-2260e35bd3fa"}