| 1 | CD | Carrier Detect | in |
| 2 | RD | Receive Data | in |
| 3 | TD | Transmit Data | out |
| 4 | DTR | Data Terminal Ready | out |
| 5 | SG | Signal Ground | |
| 6 | DSR | Data Set Ready | in |
| 7 | RTS | Request to Send | out |
| 8 | CTS | Clear to Send | in |
| 9 | RI | Ring Indicator | in |
PC to device uses a straight through cable
PC to PC uses a flipped cable