Send a custom OCPP message to a charge point. This is a synchronous endpoint that waits for the charge point response or timeout. A normal response (CALLRESULT) from the charge point is returned without transformation. When the charge point answers with an error (CALLERROR) that matches the request, it is returned as HTTP 200 with an error object holding the code, description and details from the OCPP frame. A top-level error property identifies an error response, because no standard OCPP 1.6 or 2.0.1 response contains it.

For an OCPP 2.0.1 charge point and the command RequestStartTransaction, when the payload has no remoteStartId key, the platform creates an admin authorization for the charge point (and for the EVSE matching evseId, if present) and sends its ID as remoteStartId. Every other field is sent unchanged. A remoteStartId provided by the caller (any value, including 0 or null) is passed through as-is. The authorization stays accepted regardless of the charge point's answer. The generated remoteStartId does not authorize the idToken, which goes through the normal token authorization, and it is not returned in the response.