Black Box Series 5000 Reference Manual page 38

Link Interfaces Reference
RS232 Null-Modem Cable Configuration
DB25 MALE
1
Shield
2
Transmitted Data
3
Received Data
4
Request To Send
6
Data Set Ready
20 DTE Ready
7 Signal Ground
8
Received Line Signal Detector (CD)
15
Transmit Timing DCE Source
17
Receiver Timing DCE Source
24 Transmit Timing DTE Source
The connecting cable must be a shielded cable.
This cable is needed when it is necessary to connect two units back-to-back and a set of
modems is not available. Note that this cable specifies DB25 connectors on each end to allow
direct connection to the link interface connector on each unit.
The link speed must be defined for each of the two units.
Figure 3 - 11 RS232 Null-Modem Cable
38
Shield
Received Data
Transmitted Data
Data Set Ready
Request To Send
Received Line Signal Detector (CD)
Signal Ground
DTE Ready
Receiver Timing DCE Source
Transmit Timing DCE Source
Transmit Timing DTE Source
DB25 MALE
1
3
2
6
4
8
7
20
17
15
24