The SEI-USB from US Digital Corp., Vancouver, WA, is an interface device that connects the company's SEI-compatible devices to a standard USB 1.1/2.0 port. SEI (serial encoder interface) bus is a network that connects up to 15 addressable SEI devices. The SEI-USB supplies power from the USB port to a limited number of SEI devices on the bus. The SEI bus uses two RS-485-like differential pairs, one for busy flow control and the other for bidirectional serial data.
US Digital Corp.