EP-A series is a kind of 10/100Mbps adaptive fast Ethernet fiber converter (also called optical-to-electric medium converter), which can implement mutual conversion between 10Base-T/100Base-TX twisted pair electrical signals and 100Base-FX optical signals. This type of fiber converter can extend the transmission distance of a network from 100m over copper wires to 120 Km (single-mode full duplex mode). This series of fiber converter supports two different types of network connection media: 10/100Base-TX and 100Base-FX. With the application of the switching technology and the storing & forwarding technology, the converter can implement data transmission between the two types of network connection media. This kind of converter supports transmission in dual-fiber multi-mode, dual-fiber single-mode and single-fiber single-mode fibers.