An improved Gigabaud Link Module (GLM) is provided for performing bi-directional data transfers between a host device and a serial transfer medium. The improved GLM, includes data signal transmission circuitry for reading data signals from the host device and transmitting the data signals as serial data over a first serial transfer link. Data signal receiving circuitry is also provided for receiving serial data signals from a second serial transfer link. The receiving circuitry then writes the signals to the host device. The first and second transfer links form the serial transfer medium, and the transmission and receiving circuitry provides the bi-directional data transfer between the host device and the serial transfer medium. The improved GLM further includes signal detection circuitry for determining when data signals are being received over the second serial transfer link.