A network is configured to apply power and data signals to networked devices for operation of the devices. A backup power supply module is coupled to the source of network power and to a secondary power source. The secondary power source may have an adjustable voltage level or a level fixed with relation to the network power voltage level. In the event of a loss or insufficiency of network power, power from the secondary source is automatically applied to the connected device or devices. The device may be programmed for certain failure modes and the secondary power source provides the power needed for operation in the event of loss of network power.