A DC 16-Circuit Source/Sink I/O Block is an intelligent, configurable block that can interface to a wide range of discrete DC sensors and actuators.DC 16-Circuit Source/Sink I/O Blocks have 16 discrete circuits, each easily configured to be an input, tristate input, or output. Output circuits can be connected directly to input circuits without the use of other components or inversion of logic states.Control power is tapped off the input/output device voltages wired to the terminals. No separate block power supply is needed.