The following table shows how to build an 8-wire modem cable using an 8-pin RJ-45 plug. This cable supports the Digi ALTPIN option when plugged into a Digi RJ-45 serial port.
| RJ-45 (Digi End) |
DB-25 Male (Modem End) |
|||
|---|---|---|---|---|
| Signal | Pin | Pin | Signal | |
|
DCD |
1 |
connected to |
8 |
DCD |
|
RTS |
2 |
connected to |
4 |
RTS |
|
GND |
3 |
connected (via shield) to |
1 (or shell) |
GND |
|
RxD |
4 |
connected to |
3 |
RxD |
|
TxD |
5 |
connected to |
2 |
TxD |
|
SG |
6 |
connected to |
7 |
SG |
|
CTS |
7 |
connected to |
5 |
CTS |
|
DTR |
8 |
connected to |
20 |
DTR |
When ALTPIN is enabled, DCD becomes available on pin 1 of an 8-pin RJ-45 connector (equivalent to pin 2 of a 10-pin connector).
Note: ALTPIN is not supported for the PortServer product under Windows NT. Use a full 10-wire modem cable in this case.