| UPS Signal Name |
DB-9 Male (UPS end) |
DB-9 Female (PC end) |
PC Signal Name |
| RX / Shutdown | 1 | via R=4k to 3 | TxD, also connected via R=4kOhm to pin 1 (DCD) |
| TX / AC Fail | 2 | 2,9 | RxD, RI |
| Common | 4,9 | 5 | GND |
At the PC end pins 4,6,8 (DTR, CTS, DSR) shorted.
1-----------------^^^--------------3
R -----^^^--1
R
2-----------------------------------2 and 9 (shorted)
4----
|---------------------------- 5
9----/
4 and 8 and 6 (shorted)
R=4KOhm.
Another variant:
Signal Computer UPS
DB9F DB9M
DTR 4 ----*
CTS 8 ----|
DSR 6 ----|
DCD 1 ----*
GND 5 ---------------*---- 4 Ground
|
*---- 9 Common
RI 9 ----*
|
RxD 2 ----*--------------- 2 On Battery
TxD 3 ----------[####]---- 1 Kill UPS Power
4.7K ohm


