
Chapter 4 Performance specification
4-7
1) How to connect RS-232C connector during modem connection
Cnet I/F module can communicate with devices of long distance as connected with modem. Modem and RS-
232C channel shall be connected as in [Figure4.4] below.
[Figure 4.4] Cable connection between RS-232C and modem
Cnet(9-PIN)
Modem side(25-PIN)
Pin No.
Name
Connection No. and signal direction
Name
Pin No.
1 CD
CD 8
2 RXD
RXD 3
3 TXD
TXD 2
4 DTR
DTR 20
5 SG
SG 7
6 DSR
DSR 6
7 RTS
RTS 4
8 CTS
CTS 5
9 RI
[Note]
RI 22
[Note] No. 9, RI signal is not used in Cnet I/F module.
2) How to connect connector for RS-232C in null modem mode
In null modem, connector can be connected in 7-wire (with handshake) or 3-wire (without handshake) type.
[Figure 4.5] as of 7-wire connection shows connection drawing when controlling CD(Carrier Detect) signal line by
external devices.
[Figure 4.5] Connection of 7-wire type (with handshake)
Cnet(9-PIN)
Computer/communication
devices
Pin No.
Name
Connection No. and signal direction
Name
1 CD
CD
2 RXD
RXD
3 TXD
TXD
4 DTR
DTR
5 SG
SG
6 DSR
DSR
7 RTS
RTS
8 CTS
CTS
9 RI
RI