Systech Corporation RCS/3000, Hardware Manual

Page: 16 / 32

Connecting EIA-232 Devices to the RCS/3000 10
DB-9 Pin
Number
DB-25 Pin
Number/Signal
1 DCD
9 RI
8 CTS
7 RTS
6 DSR
5 GND
4 DTR
3 TX
2 RX
8 DCD
22 RI
5 CTS
4 RTS
6 DSR
7 GND
20 DTR
2 TX
3 RX
Table 3-3: DB-9 to DB-25 Modem Cable
DB-9 Pin
Number
DB-9 Pin
Number
1 DCD
9 RI
8 CTS
7 RTS
6 DSR
5 GND
4 DTR
3 TX
2 RX
4 DTR
9 RI
7 RTS
8 CTS
5 GND
1 DCD
2 RX
3 TX
6 DSR
Table 3-4 DB-9 to DB-9 Terminal Cable
The RCS/3000 does not require the use of all 9 wires. Only pins 2, 3, and 5 are essential.
DTR/DSR and RTS/CTS (pins 4, 6, 7, and 8) are only necessary for flow control. RI is only
used as a ring indicator for modem use. Although the RCS/3000 requires DCD by default,
you can change the serial port setting so that the DCD signal is not required (see the
ignoredcd command in the Port Server Administrator’s Guide). Thus, a minimal cable as
shown in Table 3-5 below, using only RX (pin 2, data in), TX (pin 3, data out), and GND (pin
5, ground), can be used.