An intelligent multistation access unit is provided having a transmission speed detection circuit for determining the data transmission speed of an attached device attempting to gain access to a node of a multiple transmission rate digital data communications network. The intelligent multistation access unit is comprised of a speed detect circuit, which indicates the data transmission speed of the attached device, a switching circuit which directs the attached device to the speed detect circuit until switched to allow the attached device access to the network node, and a processor that controls the switching circuit and which permits the attached device access to the node depending on the data transmission speed indication.