Versatile I/O Expansion with Y Series Modules The Y Series I/O boards includes a wide selection of 26 I/O expansion boards, designed to meet complex and diverse industrial I/O requirements. Supported signal types include: Digital Input (DI), Digital Output (DO), Analog Input (AI), Analog Output (AO), RTD(PT100 or PT1000), Thermocouple (TC), RS485, RS232, Pulse Output, Pulse Counting, and IEPE sensor input.