1383.3 RS-232C Interface Specifications[ 1 ] Interface Connector and Pin AssignmentThe BHT has a direct-connect interface port which is connectable to the 3-pole mini stereo plug (φ2.5mm or 0.1") and supports a subset of the RS-232C interface as shown below.Using a direct-connect interface cable having the mini stereo plugs makes it possible to connect the BHTto a host computer (or another BHT) directly without any routing through the CU-300.3-pole Mini Stereo Plug (ø2.5 mm or 0.1")The poles of the plug are assigned as listed below.Signal Input/OutputSignal Name Function BHT External deviceSD Send data →RD Receive data ←SG Signal ground -The input/output voltage threshold for the logical valued signal is listed below.Logical Value Input Voltage Threshold(RD)Output Voltage Threshold(SD)0 3V min. 5V min.1 -3V max. -5V max.The direct-connect interface port is not designed to stand frequent connecting/disconnecting. Do notplug and unplug basically more than one time a day; otherwise, the service life of the plug willshorten. To connect the BHT to a host computer having no IrDA port (or another BHT) frequently,use the CU-300.Allow the specified signals only to enter the direct-connect interface port. Entry of other signals willresult in a failure or malfunction of the BHT.
