### RJ-45 8-Pin to Modem (ALTPIN option)

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.

##### 8-Wire Modem Cable Supporting ALTPIN Option

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.