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Installation DART 300 Modem
Page 90 2110212 Rev 1.0
Two sample connections are shown below. Determine the control signal capabilities and
requirements for the local host device and construct the required cabling. Both ends of the cable
should use male connectors as DCE devices use a female connector on the unit.
DCE (modem) DCE (host)
1 DCD Not Connected 1 DCD
2 RxD 2 RxD
3 TxD 3 TxD
4 DTR 4 DTR
5 GND 5 GND
6 DSR 6 DSR
7 RTS 7 RTS
8 CTS 8 CTS
9 RI Not Connected 9 RI
Figure 10-2: Full Function Null-Modem.
DCE (modem) DCE (host)
1 DCD Not Connected 1 DCD
2 RxD 2 RxD
3 TxD 3 TxD
4 DTR 4 DTR
5 GND 5 GND
6 DSR 6 DSR
7 RTS 7 RTS
8 CTS Not Connected 8 CTS
9 RI Not Connected 9 RI
Figure 10-3: Minimum Connection Null-Modem (without flow control).
10.3.2. Cable Length
Standard RS-232C communications cables function properly for distances up to 50 feet, provided
the driver circuits meet RS-232C voltage specifications. If longer lengths are required, low loss
RS-232 cable or electronic cable extenders can be used; both are available from local cable
distributors or electronic catalogs.