Check the listing for details. National Instruments NI 9401 cDAQ Digital Input / Output Module. Condition: Used. Listed at 195.00 USD. National Instruments 9401 digital I/O module. Tested, fully functional, and in excellent physical condition. 5 V/TTL, 8 Bidirectional Channels, 100 ns C Series Digital Module—The NI‑9401 is a configurable digital I/O interface for input or output in 4‑bit increments. Therefore, the NI‑9401 can create three configurations: 8 digital inputs, 8 digital outputs, or four digital inputs and four digital outputs. With reconfigurable I/O (RIO) technology (CompactRIO only), you can use the LabVIEW FPGA Module to program the NI‑9401 for implementing custom, high-speed counter/timers; digital communication protocols; pulse generation; and more. Each channel features transient isolation between the I/O channels and the backplane. For additional information and resources, use the model name to search the manufacturer's website.