1 GND

2 R=25 or 33 KOhm to GND in data or charge cable

3 +6v charge voltage

4 Tx USB

5 Rx USB

6 RTS

7 Vbus (connect to pin 3 if not used as IC power)

8 CTS

9 DCD

10 RE

11 DTR

12 DSR

13 Serial Enable (if this pin is not pulled to ground your serial cable will not work)