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Quick Start
Modems
The easiest way to connect modems is to use Digi’s RJ-45 to DB-25 straight-through cables,
which offer full 10-pin connections for full modem control. (You may find ten-pin RJ-45
connectors difficult to find in the retail market). Here are the choices and part numbers:
DB-25 Male
DB-25
Female
DB-9 Male
24 Inch Cables
61020024
61030024
61070024
48 Inch Cables
61020048
61030048
N/A
If you wish to build your own modem cables, follow the diagram below. Cables must be shielded
to remain in compliance with FCC certification requirements, and the shield should be con-
nected to Chassis Ground (GND) at one end of the cable run.
Full 10-Wire Modem Cable
RJ-45 - 10 Pin
DB-25 Male
1
2
3
4
5
6
7
8
9
10
Pin
Pin
RI
DSR
RTS
GND
TxD
RxD
SG
CTS
DTR
DCD
RI
DSR
RTS
GND
TxD
RxD
SG
CTS
DTR
DCD
Signal
22
6
4
1
2
3
7
5
20
8
Signal
(
= Cable Shield)
Pin 1
Pin 10
Now connect the modem(s) to the other ports as previously described, plugging the RJ-45 or RJ-
11 connectors from the modems into the appropriate sockets in the back of the PortServer. Again,
make sure the power is off on the PortServer and the modems!
If you want to use 8-pin RJ-45 to DB-25 adapters, a software feature called ALTPIN has been
incorporated into the PortServer software to swap the DCD and DSR signals. This makes DCD
available on pin 1 of an 8-pin RJ-45 connector. See Altpin on page 97.