The SEI-USB is an interface module that connects the company’s SEI compatible devices to a standard USB 1.1/2.0 port. The SEI (Serial Encoder Interface) bus is a simple, quick, and convenient network that connects up to 15 addressable SEI devices using a single 6-wire telephone-type cable up to 1,000 feet long. The SEI bus uses two RS-485-like differential pairs, one for “busy” flow control and the other for bi-directional serial data. The SEI-USB will supply power from the USB port to a modest number of SEI devices on the bus (for example, five A2 encoders at a distance of 250 feet). The SEI-USB limits the power to the maximum design spec of the USB port. A red LED will be lit when additional power is required and the PS-12 power supply should then be used.