DATA COMMUNICATION APPARATUS

摘要

A base module (2) has a subsidiary unit receiving area (3b) having a first electrical coupler (LC1). A subsidiary unit (4) has a memory (231) and a second electrical coupler (LC2) arranged to couple to the first electrical coupler when the subsidiary unit is received on the subsidiary unit receiving area (3b). The base module (2) has a signal supplier (10, 21) for supplying a signal to the subsidiary unit (4) when the first and second electrical couplers (LC1 and LC2) are coupled and a data communicator (10, 22) for interrupting the signal in accordance with data to be communicated to the subsidiary unit to provide to the first coupler (LC1) an interrupted signal having interruptions dependent upon the data to be communicated. The data communicator is arranged to send the data as data bits each followed by a confirmation bit and the subsidiary unit has a data returner (33, M1) for modifying the received signal to return the received data as it is received so that each returned data bit is followed by the inverse of the corresponding confirmation bit.