Abstract: A power monitor device includes a channel monitoring interface for monitoring a power rail, a data storage device including a data buffer, and measurement circuitry connected to the channel monitoring interface to generate a series of channel measurement samples associated with the power rail. The power monitor device includes control circuitry to store the channel measurement samples in the data buffer, detect a defined excursion event at an event detection time based at least on an event triggering sample of the channel measurement samples, and in response, store a sample set including the event triggering sample and at least one channel measurement sample stored in the data buffer prior to the event triggering sample. The control circuitry may subsequently receive a request for the stored sample set, and provide access to the stored sample set.