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 | 6 | DCD |
| RTS | 2 | connected to | 4 | RTS |
| GND | 3 | connected (via shield) to | 1 (or shell) | GND |
| TxD | 4 | connected to | 3 | RxD |
| RxD | 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.