| Pin | Signal | Description |
| 1 | Gnd | |
| 2 | USB D+ | connected with PC USB D+ (pin 3) in USB data cable |
| 3 | USB D- | connected with PC USB D- (pin 2) in USB data cable |
| 4 | USB Vbus | connected with PC USB Vbus (pin 1) in USB data cable |
| 7 | Rx | at least for VS2, VS3 |
| 9 | Tx | at least for VS2, VS3 |
+9v additional power needed in COM (not USB) cable


