7.4 RS232 interface
The RS232 interface is the interface for the application software and the
connection to the PC. The customer application communicates with the Modem
by AT cellular commands. The RS232 interface is implemented as a 9-pin D-Sub
socket with two screws fitting.
Pin assignments:
Signal
Pin
Input/Output
Description
DCD
1
Output
RXD
2
Input
TXD
3
Output
DTR
4
Output
GND
5
DSR
6
X
RTS
7
Output
CTS
8
Input
RI
9
Input
Serial port V.24 protocol(for reference)
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