| UPS Pin Number | UPS Pin Name | Direction | Computer Pin Number | Computer Pin Name | Description | 
|---|---|---|---|---|---|
| n/a | Shield | -- | n/a | Shield | Frame/Case Ground | 
| 1 | DCD | Connected to Shield | |||
| 8 | CTS | Connected to Shield | |||
| 9 | RI | Connected to Shield | |||
| 4 | DTR | Connected to pin 6 | |||
| 6 | DSR | Connected to pin 4 | |||
| 1 | RS232 Receive Data | <-- | 3 | TxD | TxD Send | 
| 2 | RS232 Transmit Data | --> | 2 | RxD | RxD Receive | 
| 4 | Signal Ground (Common) | -- | 5 | GND | Ground | 
| 6 | Remote Shutdown | <-- | 7 | RTS | Kill UPS Power | 
It is authentically known that this type of a UPS cable is completely compatible to all APC Smart-UPS with DB9 serial ports (though about this fact there is no information on an official site of the manufacturer www.apc.com).
UPS (DB9M)                              IBM PC (DB9F)
-----------                             -------------
Shield        x-------------------------+----x Shield
                                        |----< 1 DCD
                                        |----< 8 CTS
                                        +----< 9 RI
TxD Send    2 <------------------------------< 2 RxD
RxD Receive 1 <------------------------------< 3 TxD
Common      4 <------------------------------< 5 GND
Shutdown    6 <------------------------------< 7 RTS
                                        +----< 4 DTR
                                        |----< 6 DSR





 правильная
правильная с ошибками
с ошибками