Abstract: An apparatus for monitoring selected one of multiple channels comprises a counting unit for increasing a count value when an up mode is selected and for decreasing the count value when a down mode is selected, wherein the count value corresponds to a channel number of the multiple channels; a mode selecting unit for selecting one of the up and the down modes; a unit for inputting a channel number; a unit for generating a count value corresponding to the channel number from the inputting unit and a write-enable signal; a source selecting unit for selecting one of the count values from the counting unit and from the generating unit; a signal generating unit for generating a channel selecting signal corresponding to the count value; a converting unit for extracting data from a channel depicted by the channel selecting signal and converting transmission rate of the data; and an analyzing unit for monitoring the data from the converting unit to check whether or not the data is transferred properly.