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Pin Signal Description Direction
1 - unswitched (+5v at 10 uA) output
2 TxD transmit data output
3 RxD receive data input
4 RTS ready to send output
5 CTS clear to send input
6 - reserved for future use -
7 GND Ground
8 DCD data carrier detect input
9 DTR switched (+5v at 1mA) output
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