Dell 5600R OL HV-US - Manual (Page 55)

55 Additional UPS Features |
Table 9. RS-232 Communication Port Pin Assignment
Pin Signal Name Function Direction from the UPS
1 Unused —
2 Tx Transmit to external device Out
3 Rx Receive from external device In
4 Unused —
5 GND Signal common (tied to chassis) —
6 Unused —
7 Unused —
8 Unused —
9 Unused —
NOTE: Unused pins must be left free on all models.