Operation in which certain components, such as nodes, facilities, circuits, or equipment, are in an operational state at all times. Note: Continuous operation usually requires that there be fully redundant configuration, or at least a sufficient X out of Y degree of redundancy for compatible equipment, where X is the number of spare components and Y is the number of operational components. 2. In data transmission, operation in which the master station need not stop for a reply from a slave station after transmitting each message or transmission block.