Chapter 7: Null Modem Cable Specifications
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7. Null Modem Cable Specifications
The DB9 cable is used for connecting a terminal or terminal emulator to the Managed Switch’s RS-232 port to access the command-
line interface.
The table below shows the pin assignments for the DB9 cable.
Function
Mnemonic
Pin
Carrier
CD
1
Receive Data
RXD
2
Transmit Data
TXD
3
Data Terminal Ready
DTR
4
Signal Ground
GND
5
Data Set Ready
DSR
6
Request To Send
RTS
7
Clear To Send
CTS
8
The 9-pin null-modem cable’s pin assignment is as follows:
CD 1 ......................................................4 DTR
DSR 6--| 1 CD
DTR 4..................................................|--6 DSR
RXD
2 ....................................................3
TXD
TXD
3 ....................................................2
RXD
GND 5....................................................5 GND
RTS
7 .....................................................8
RTS
CTS 8..................................................... 7 RTS
Reserve 9 .............................................. 9 Reserve