| UPS Pin Number | UPS Pin Name | Direction | Computer Pin Number | Computer Pin Name | Description | 
|---|---|---|---|---|---|
| n/a | Shield | -- | n/a | Shield | Frame/Case Ground | 
| 1 | Remote Shutdown | <-- | 7 | RTS | Kill UPS Power | 
| 3 | Normally Open On-Battery Contact | --> | 8 | CTS | On Battery | 
| 4 | Alternate Remote Shutdown | <-- | 3 | TxD | Alternate Kill UPS Power | 
| 5 | Normally Open Low-Battery-Alarm Contact | --> | 1 | DCD | Low Battery | 
| 9 | Signal Ground (Common) | -- | 5 | GND | Ground | 
| * | <-- | 4 | DTR | DTR set to +5V by software | 
* -- computer pin 4 (DTR) is connected to computer pin 1 (DCD) via the resistor 10k, and also it is connected to computer pin 8 (CTS) via the resistor 10k.
UPS (DB9M)                                          IBM PC (DB9F)
-----------                                         -------------
Shutdown     1 <------------------------------------------< 7 RTS
Alt Shutdown 4 <------------------------------------------< 3 TxD
Common       9 <------------------------------------------< 5 GND
PWR_FAIL     3 <---------------------------+--------------< 8 CTS
                                          [#] R1 10k
                                           +--------------< 4 DTR
                                          [#] R2 10k
LOW_BATT     5 <---------------------------+--------------< 1 DCD





 правильная
правильная с ошибками
с ошибками