Various aspects of the instant disclosure are directed towards a method for communicating time-based data in a power line communication system. In accordance with one or more example embodiments, firmware is downloaded to a multitude of endpoints over power distribution lines carrying alternating current (AC) power. Endpoint devices targeted for changes to stored firmware are grouped and the firmware is delivered in chunks to each group. As devices receive a particular chunk of firmware, the device advances to a next stage and provides information indicative of this stage, based upon which subsequent chunks of firmware are communicated. This occurs (e.g., on a daily cycle) until the endpoint has received all firmware for an update, after which the endpoint(s) are re-started using the firmware. Accordingly, such updates can be carried out in a cyclic and verifiable manner.