| Pin | Signal | Description |
| 6,17 | GND | |
| 10 | Tx | should be connected by R=22KOhm to pins 1,13 in cable (optional?). |
| 21 | Rx | should be connected by R=22KOhm to pins 1,13 in cable (optional?). |
+5v should be supplied directly to pins 1,13 and to pin 22 via R=1KOhm in cable (unconfirmed).

