To secure communications from a process plant across a unidirectional data diode to a remote system, a sending device at the plant end publishes data across the diode to a receiving device at the remote end. The publication of various data is respectively in accordance with context information (e.g., identification of data sources, respective expected rate of data generation/arrival, etc.) that is descriptive of data sources of the plant and that is recurrently provided by the sending device across the diode. A recurrence interval may be based on a tolerance for lost data or another characteristic of an application, service, or consumer of data at the remote system. The publishing may leverage an industrial communication protocol (e.g., HART-IP) and/or a suitable general-purpose communication protocol (e.g., JSON).