|
Pin |
Pin Name |
Description (may be empty) |
| 1 | DCD | |
| 2 | TX | |
| 3 | RX | |
| 4 | DTR | |
| 5 | GND | |
| 6 | DSR | |
| 7 | ||
| 8 | ||
| 9 | +12V | +12V if 1,4 and 6 are shorted |
PC toggles a bit on the DTR line and check the DSR and DCD lines. If the lines are shorted, pin 9 (normally RI) is used to provide 12V power. See patent for more information

