The following cable wiring supports most serial terminals or printers with either software or hardware handshaking. This cable is valid with any Digi DB-25 serial port.
Most terminals and printers use Data Terminal Ready (DTR) for Ready/Busy hardware handshaking. The following cable wiring supports this method.
| DB-25 (Digi End) |
DB-25 Male (Terminal/Printer) |
|||
|---|---|---|---|---|
| Signal | Pin | Pin | Signal | |
| RTS | 4 | connected to | 5 | CTS |
| GND | Shell | connected to | Shell | GND |
| TxD | 2 | connected to | 3 | RxD |
| RxD | 3 | connected to | 2 | TxD |
| SG | 7 | connected to | 7 | SG |
| CTS | 5 | connected to | 20 | DTR* |
| DTR | 20 | connected to | 8 and 6 | DCD and DSR** |
| DCD and DSR | 8 and 6 | connected to | 4 | RTS |
* Okidata Printers may use SSD (pin 11) instead.
**Some printers require DSR. If DSR is required, it should be either wired or the
printer set to ignore DSR (DSR Invalid).
Important: Other printer manufacturers may use different methods of flow control. Consult your printer's documentation for specific wiring requirements.