Direct Digital Control (DDC) system Let’s go back a few decades to early computerized control. The predecessor of the DCS and the PLC was the Direct Digital Control (DDC) system. Many vendors such as Taylor Instruments, Bailey Control, and Foxboro had DDC systems that centered on a mini-computer connected to several proprietary I/O devices located at Remote locations around the plant. Watch the video and complete the statement below A major difference between an old DDC system and a current DCS