A system for controlling a subsea device comprises a complimentary set of data communication interfaces operatively coupled to an electronically interrogatable component of a subsea device and a remotely disposed device controller via a power conductor which defined data pathway between the subsea device and the remotely disposed device controller. A data transceiver is operatively coupled to the electronically interrogatable component and the remotely disposed device controller via the complimentary set of data communication interfaces over the power conductor. In configurations, control and/or telemetry or other data may be unidirectionally and/or bidirectionally transmitted between the electronically interrogatable component of a subsea device and a remotely disposed device controller. In configurations, data faults may be monitored in a primary data path and, if a fault detected, control and/or telemetry or other data transmission switched to the power conductor data pathway, manually and/or automatically.