This product is an USB2.0-compliant digital I/O unit used to provide a digital signal I/O function on a PC. This product can input and output digital signals at 12VDC. This product features 16 channels of Optocoupler isolated inputs (compatible with current sink output) and 16 channels of Optocoupler isolated open-collector outputs (current sink type). You can use 16 input signals as interrupt inputs. Equipped with the digital filter function to prevent wrong recognition of input signals and output transistor protection circuit (surge voltage protection and over current protection).