All of the signal lines are processed as 22 Kohm pull-down in the RS-232C (V.24) port of LINEEYE protocol analyzers. If the receiver of the target devices has signal lines not in use (Synchronous clock for example) and the transmitter of the target devices controls the usage of those lines, there is a possibility that connection of the protocol analyzer to the target device may decrease the influence of cross-talk and prevent the error.