Draw pin diagram of DB9 connector, stating function of each pin.
1 Answer

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Pin No Name Dir Description
1 DCD IN Data Carrier Detect. Raised by DCE when modem synchronized.
2 RD IN Receive Data (a.k.aRxD, Rx). Arriving data from DCE.
3 TD OUT Transmit Data (a.k.aTxD, Tx). Sending data from DTE.
4 DTR OUT Data Terminal Ready. Raised by DTE when powered on. In autoanswer mode raised only when RI arrives from DCE.
5 SGND - Ground
6 DSR IN Data Set Ready. Raised by DCE to indicate ready.
7 RTS OUT Request To Send. Raised by DTE when it wishes to send. Expects CTS from DCE.
8 CTS IN Clear To Send. Raised by DCE in response to RTS from DTE.
9 RI IN Ring Indicator. Set when incoming ring detected - used for autoanswer application. DTE raised DTR to answer.
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