The operation of a powered device is monitored to detect a failure condition, the powered device connected to power sourcing equipment by a communications channel including inline power delivery from the power sourcing equipment to the powered device. Diagnostic information is captured including (i) configuration and status information identifying the power sourcing equipment, the communications channel, and status of the inline power delivery at the time of detection of the failure condition, and (ii) failure information identifying the failure condition. This diagnostic information is stored as diagnostic information signals in an electronic memory which is electronically accessible by an external user as part of a failure analysis process. By this process, diagnostic information pertaining to the operation of the powered device with the power sourcing equipment and the communications channel is captured and stored, providing greater information for more thorough failure analysis.